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Duncan GD, Ellis AG, Forest F, Verboom GA. Strong habitat and seasonal phenology effects on the evolution of self-compatibility, clonality and pollinator shifts in Lachenalia (Asparagaceae: Scilloideae). THE NEW PHYTOLOGIST 2024; 244:307-317. [PMID: 38702970 DOI: 10.1111/nph.19786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 04/09/2024] [Indexed: 05/06/2024]
Abstract
Plants employ a diversity of reproductive safeguarding strategies to circumvent the challenge of pollen limitation. Focusing on southern African Lachenalia (Asparagaceae: Scilloideae), we test the hypothesis that the evolution of reproductive safeguarding traits (self-compatibility, autonomous selfing, bird pollination and clonal propagation) is favoured in species occupying conditions of low insect abundance imposed by critically infertile fynbos heathland vegetation and by flowering outside the austral spring insect abundance peak. We trace the evolution of these traits and selective regimes on a dated, multi-locus phylogeny of Lachenalia and assess their evolutionary associations using ordinary and phylogenetic regression. Ancestral state reconstructions identify an association with non-fynbos vegetation and spring flowering as ancestral in Lachenalia, the transition to fynbos vegetation and non-spring flowering taking place multiple times. They also show that self-compatibility, autofertility, bird pollination and production of multiple clonal offsets have evolved repeatedly. Regression models suggest that bird pollination and self-compatibility are selected for in fynbos and in non-spring flowering lineages, with autofertility being positively associated with non-spring flowering. These patterns support the interpretation of these traits as reproductive safeguarding adaptations under reduced insect pollinator abundance. We find no evidence to support the interpretation of clonal propagation as a reproductive safeguarding strategy.
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Affiliation(s)
- Graham D Duncan
- Bolus Herbarium and Department of Biological Sciences, University of Cape Town, 7701, Rhodes Gift, South Africa
- Kirstenbosch National Botanical Garden, South African National Biodiversity Institute, 99 Rhodes Ave, Newlands, Cape Town, 7700, South Africa
| | - Allan G Ellis
- Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa
| | - Félix Forest
- Royal Botanic Gardens, Kew, Richmond, TW9 3AE, Surrey, UK
| | - G Anthony Verboom
- Bolus Herbarium and Department of Biological Sciences, University of Cape Town, 7701, Rhodes Gift, South Africa
- Department of Biology and Environmental Science, University of Gothenburg, 40530, Gothenburg, Sweden
- Gothenburg Botanical Garden (Botaniska), 41319, Gothenburg, Sweden
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2
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Balogh CM, Barrett SCH. An experimental field study of inbreeding depression in an outcrossing invasive plant. FRONTIERS IN PLANT SCIENCE 2024; 15:1393294. [PMID: 39267999 PMCID: PMC11390429 DOI: 10.3389/fpls.2024.1393294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 08/09/2024] [Indexed: 09/15/2024]
Abstract
Inbreeding depression is likely to play an important role during biological invasion. But relatively few studies have investigated the fitness of selfed and outcrossed offspring in self-incompatible invasive plants in natural environments in their introduced range. Moreover, the majority of studies on inbreeding depression have investigated self-compatible species with mixed mating, and less is known about the intensity of inbreeding depression in outcrossing self-incompatible species. Here, we address these questions experimentally by comparing selfed and outcrossed progeny of purple loosestrife (Lythrum salicaria) over four growing seasons, including three under field conditions in a freshwater marsh in southern Ontario, Canada, a region where L. salicaria is highly invasive. The tristylous mating system of L. salicaria involves disassortative mating among floral morphs enforced by trimorphic incompatibility. However, owing to partial incompatibility, self-fertilized seed can be obtained by manual self-pollination thus facilitating comparisons of selfed and outcrossed progeny. We compared progeny with and without intraspecific competition from selfed or outcrossed neighbours and examined the influence of breeding treatment and competition on fitness correlates by measuring a range of life-history traits including: proportion of seeds germinating, days to germination, survival, proportion of plants flowering, time to flowering, vegetative mass, and inflorescence number and mass. We analysed data for each trait using functions from time series estimates of growth and two multiplicative estimates of fitness. We detected varying intensities of inbreeding depression for several traits in three of the four years of the experiment, including inflorescence mass and reproductive output. Cumulative inbreeding depression over four years averaged δ = 0.48 and 0.68, depending on the method used to estimate multiplicative fitness. The competition treatments did not significantly affect plant performance and the magnitude of inbreeding depression. Given the primarily outcrossing mating system of L. salicaria populations, the detection of inbreeding depression for several key life-history traits was as predicted by theory. Our results suggests that biparental inbreeding and low selfing in colonizing populations may have significant effects on demographic parameters such as population growth.
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Affiliation(s)
- Christopher M Balogh
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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3
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Tusuubira SK, Kelly JK. Experimental evolution suggests rapid assembly of the 'selfing syndrome' from standing variation in Mimulus guttatus. FRONTIERS IN PLANT SCIENCE 2024; 15:1378568. [PMID: 39263417 PMCID: PMC11388319 DOI: 10.3389/fpls.2024.1378568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 07/23/2024] [Indexed: 09/13/2024]
Abstract
Ecological and evolutionary changes are likely to occur rapidly when outcrossing populations experience pollinator loss. However, the number and identify of plant traits that will respond to this form of selection, as well as the overall predictability of evolutionary responses, remain unclear. We experimentally evolved 20 large replicate populations of Mimulus guttatus for 10 generations under three treatments: pure outcrossing, mixed mating (10% outcrossing) and pure selfing. These populations were founded from the same genetically diverse and outcrossing natural population. After 10 generations, all measured traits evolved with flower size, phenology, and reproductive traits diverging consistently among mating system treatments. Autogamy increased dramatically in the selfing treatment, but the magnitude of adaptation only becomes clear once inbreeding depression is factored out. Selfing treatment plants evolved reduced stigma-anther separation, and also exhibited declines in flower size and per-flower reproductive capacity. Flower size also declined in selfing populations but this was driven mainly by inbreeding depression and cannot be attributed to adaptation towards the selfing syndrome. Generally, the mixed mating populations evolved trait values intermediate to the fully selfing and outcrossing populations. Overall, our experimental treatments reiterated differences that have been documented in interspecific comparisons between selfing and outcrossing species pairs. Given that such contrasts involve species separated by thousands or even millions of generations, it is noteworthy that large evolutionary responses were obtained from genetic variation segregating within a single natural population.
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Affiliation(s)
- Sharifu K Tusuubira
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, United States
| | - John K Kelly
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, United States
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4
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Nery EK, Caddah MK, Michelangeli FA, Nogueira A. An evolutionary disruption of the buzz pollination syndrome in neotropical montane plants. AMERICAN JOURNAL OF BOTANY 2024; 111:e16367. [PMID: 38956979 DOI: 10.1002/ajb2.16367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/17/2024] [Accepted: 04/18/2024] [Indexed: 07/04/2024]
Abstract
PREMISE Under pollinator limitations, specialized pollination syndromes may evolve toward contrasting responses: a generalized syndrome with increased pollinator attraction, pollinator reward, and pollen transfer capacity; or the selfing syndrome with increased self-pollen deposition, but reduced pollinator attraction and pollen transfer capacity. The buzz-pollination syndrome is specialized to explore female vibrating bees as pollinators. However, vibrating bees become less-active pollinators at montane areas of the Atlantic Forest (AF) domain. This study investigated whether the specialized buzz-pollination syndrome would evolve toward an alternative floral syndrome in montane areas of the AF domain, considering a generalized and the selfing syndromes as alternative responses. METHODS We utilized a lineage within the buzz-pollinated Miconia as study system, contrasting floral traits between montane AF-endemic and non-endemic species. We measured and validated floral traits that were proxies for pollinator attraction, reward access, pollen transfer capacity, and self-pollen deposition. We inferred the evolution of floral trait via phylogenetic comparative methods. RESULTS AF-endemic species have selectively evolved greater reward access and more frequently had generalist pollination. Nonetheless, AF-endemic species also have selectively evolved toward lower pollen transfer capacity and greater self pollination. These patterns indicated a complex evolutionary process that has jointly favored a generalized and the selfing syndromes. CONCLUSIONS The buzz pollination syndrome can undergo an evolutionary disruption in montane areas of the AF domain. This floral syndrome is likely more labile than often assumed, allowing buzz-pollinated plants to reproduce in environments where vibrating bees are less-reliable pollinators.
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Affiliation(s)
- Eduardo K Nery
- Programa de Pós-Graduação em Evolução e Diversidade, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil
- Laboratório de Interações Planta-Animal (LIPA), Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil
| | - Mayara K Caddah
- Departamento de Botânica, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | | | - Anselmo Nogueira
- Laboratório de Interações Planta-Animal (LIPA), Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, São Bernardo do Campo, SP, Brazil
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5
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Ho DV, Tormey D, Odell A, Newton AA, Schnittker RR, Baumann DP, Neaves WB, Schroeder MR, Sigauke RF, Barley AJ, Baumann P. Post-meiotic mechanism of facultative parthenogenesis in gonochoristic whiptail lizard species. eLife 2024; 13:e97035. [PMID: 38847388 PMCID: PMC11161175 DOI: 10.7554/elife.97035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Accepted: 05/17/2024] [Indexed: 06/09/2024] Open
Abstract
Facultative parthenogenesis (FP) has historically been regarded as rare in vertebrates, but in recent years incidences have been reported in a growing list of fish, reptile, and bird species. Despite the increasing interest in the phenomenon, the underlying mechanism and evolutionary implications have remained unclear. A common finding across many incidences of FP is either a high degree of homozygosity at microsatellite loci or low levels of heterozygosity detected in next-generation sequencing data. This has led to the proposal that second polar body fusion following the meiotic divisions restores diploidy and thereby mimics fertilization. Here, we show that FP occurring in the gonochoristic Aspidoscelis species A. marmoratus and A. arizonae results in genome-wide homozygosity, an observation inconsistent with polar body fusion as the underlying mechanism of restoration. Instead, a high-quality reference genome for A. marmoratus and analysis of whole-genome sequencing from multiple FP and control animals reveals that a post-meiotic mechanism gives rise to homozygous animals from haploid, unfertilized oocytes. Contrary to the widely held belief that females need to be isolated from males to undergo FP, females housed with conspecific and heterospecific males produced unfertilized eggs that underwent spontaneous development. In addition, offspring arising from both fertilized eggs and parthenogenetic development were observed to arise from a single clutch. Strikingly, our data support a mechanism for facultative parthenogenesis that removes all heterozygosity in a single generation. Complete homozygosity exposes the genetic load and explains the high rate of congenital malformations and embryonic mortality associated with FP in many species. Conversely, for animals that develop normally, FP could potentially exert strong purifying selection as all lethal recessive alleles are purged in a single generation.
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Affiliation(s)
- David V Ho
- Department of Biology, Johannes Gutenberg UniversityMainzGermany
- Institute of Quantitative and Computational Biosciences, Johannes Gutenberg UniversityMainzGermany
| | - Duncan Tormey
- Stowers Institute for Medical ResearchKansas CityUnited States
| | - Aaron Odell
- Department of Biology, Johannes Gutenberg UniversityMainzGermany
| | | | | | - Diana P Baumann
- Stowers Institute for Medical ResearchKansas CityUnited States
| | | | | | | | - Anthony J Barley
- School of Mathematical and Natural Sciences, Arizona State University–West Valley CampusGlendaleUnited States
| | - Peter Baumann
- Department of Biology, Johannes Gutenberg UniversityMainzGermany
- Institute of Quantitative and Computational Biosciences, Johannes Gutenberg UniversityMainzGermany
- Institute of Molecular BiologyMainzGermany
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Keller B, Alther B, Jiménez A, Koutroumpa K, Mora-Carrera E, Conti E. Island plants with newly discovered reproductive traits have higher capacity for uniparental reproduction, supporting Baker's law. Sci Rep 2024; 14:11392. [PMID: 38762587 PMCID: PMC11102434 DOI: 10.1038/s41598-024-62065-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 05/13/2024] [Indexed: 05/20/2024] Open
Abstract
Uniparental reproduction is advantageous when lack of mates limits outcrossing opportunities in plants. Baker's law predicts an enrichment of uniparental reproduction in habitats colonized via long-distance dispersal, such as volcanic islands. To test it, we analyzed reproductive traits at multiple hierarchical levels and compared seed-set after selfing and crossing experiments in both island and mainland populations of Limonium lobatum, a widespread species that Baker assumed to be self-incompatible because it had been described as pollen-stigma dimorphic, i.e., characterized by floral morphs differing in pollen-surface morphology and stigma-papillae shape that are typically self-incompatible. We discovered new types and combinations of pollen and stigma traits hitherto unknown in the literature on pollen-stigma dimorphism and a lack of correspondence between such combinations and pollen compatibility. Contrary to previous reports, we conclude that Limonium lobatum comprises both self-compatible and self-incompatible plants characterized by both known and previously undescribed combinations of reproductive traits. Most importantly, plants with novel combinations are overrepresented on islands, selfed seed-set is higher in islands than the mainland, and insular plants with novel pollen-stigma trait-combinations disproportionally contribute to uniparental reproduction on islands. Our results thus support Baker's law, connecting research on reproductive and island biology.
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Affiliation(s)
- Barbara Keller
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland.
| | - Barbara Alther
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Ares Jiménez
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Konstantina Koutroumpa
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
- Botanischer Garten und Botanisches Museum Berlin (BGBM), Freie Universität Berlin, Berlin, Germany
| | - Emiliano Mora-Carrera
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | - Elena Conti
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
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7
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Núñez-Hidalgo S, Cascante-Marín A. Selfing in epiphytic bromeliads compensates for the limited pollination services provided by nectarivorous bats in a neotropical montane forest. AOB PLANTS 2024; 16:plae011. [PMID: 38497049 PMCID: PMC10944016 DOI: 10.1093/aobpla/plae011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/23/2024] [Indexed: 03/19/2024]
Abstract
Abstract. Plants with specialized pollination systems frequently exhibit adaptations for self-pollination, and this contradictory situation has been explained in terms of the reproductive assurance function of selfing. In the neotropics, several plant lineages rely on specialized vertebrate pollinators for sexual reproduction, including the highly diverse Bromeliaceae family, which also displays a propensity for selfing. Thus far, the scarce evidence on the role of selfing in bromeliads and in other neotropical plant groups is inconclusive. To provide insights into the evolution and persistence of self-fertilization in the breeding systems of Bromeliaceae, we studied four sympatric epiphytic species from the genus Werauhia (Tillandsioideae) in Costa Rica. We documented their floral biology, pollination ecology and breeding systems. We estimated the contribution of selfing by comparing the reproductive success between emasculated flowers requiring pollinator visits and un-manipulated flowers capable of selfing and exposed to open pollination across two flowering seasons. The studied species displayed specialized pollination by nectar-feeding bats as well as a high selfing ability (auto-fertility index values > 0.53), which was attained by a delayed selfing mechanism. Fruit set from natural cross-pollination was low (<26% in both years) and suggested limited pollinator visitation. In line with this, we found a very low bat visitation to flowers using video-camera recording, from 0 to 0.24 visits per plant per night. On the contrary, the contribution of selfing was comparatively significant since 54-80% of the fruit set from un-manipulated flowers can be attributed to autonomous self-pollination. We concluded that inadequate cross-pollination services diminished the reproductive success of the studied Werauhia, which was compensated for by a delayed selfing mechanism. The low negative effects of inbreeding on seed set and germination likely reinforce the persistence of selfing in this bromeliad group. These results suggest that selfing in bat-pollinated bromeliads may have evolved as a response to pollinator limitation.
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Affiliation(s)
- Stephanie Núñez-Hidalgo
- Sistema de Estudios de Posgrado, Universidad de Costa Rica, San Pedro de Montes de Oca, 11501-2060 San José, Costa Rica
| | - Alfredo Cascante-Marín
- Escuela de Biología y Centro de Investigación en Biodiversidad y Ecología Terrestre (CIBET), Universidad de Costa Rica, San Pedro de Montes de Oca, 11501-2060 San José, Costa Rica
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8
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Scott MF, Mackintosh C, Immler S. Gametic selection favours polyandry and selfing. PLoS Genet 2024; 20:e1010660. [PMID: 38363804 PMCID: PMC10903963 DOI: 10.1371/journal.pgen.1010660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 02/29/2024] [Accepted: 01/22/2024] [Indexed: 02/18/2024] Open
Abstract
Competition among pollen or sperm (gametic selection) can cause evolution. Mating systems shape the intensity of gametic selection by determining the competitors involved, which can in turn cause the mating system itself to evolve. We model the bidirectional relationship between gametic selection and mating systems, focusing on variation in female mating frequency (monandry-polyandry) and self-fertilisation (selfing-outcrossing). First, we find that monandry and selfing both reduce the efficiency of gametic selection in removing deleterious alleles. This means that selfing can increase mutation load, in contrast to cases without gametic selection where selfing purges deleterious mutations and decreases mutation load. Second, we explore how mating systems evolve via their effect on gametic selection. By manipulating gametic selection, polyandry can evolve to increase the fitness of the offspring produced. However, this indirect advantage of post-copulatory sexual selection is weak and is likely to be overwhelmed by any direct fitness effects of mating systems. Nevertheless, gametic selection can be potentially decisive for selfing evolution because it significantly reduces inbreeding depression, which favours selfing. Thus, the presence of gametic selection could be a key factor driving selfing evolution.
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Affiliation(s)
- Michael Francis Scott
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom
| | - Carl Mackintosh
- CNRS, UMR7144 Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
- Sorbonne Universités, UPMC Université Paris VI, Roscoff, France
| | - Simone Immler
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom
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Xu YW, Sun L, Ma R, Gao YQ, Sun H, Song B. Does pollinator dependence decrease along elevational gradients? PLANT DIVERSITY 2023; 45:446-455. [PMID: 37601546 PMCID: PMC10435910 DOI: 10.1016/j.pld.2023.03.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/15/2023] [Accepted: 03/19/2023] [Indexed: 08/22/2023]
Abstract
Plants have long been thought to be less dependent on pollinators for seed production at higher elevations due to adverse pollination environments. However, recent research has yet to consistently support the generality of this expectation. In this study, we asked whether pollinator dependence decreases along an elevational gradient and how it varies with various reproductive traits. To answer these questions, we quantified pollinator-plant associations and various reproductive traits for 112 flowering plants spanning a large elevational gradient (990-4260 m a.s.l.) in the Qinghai-Tibet Plateau. We found that flowering plants in the Qinghai-Tibet Plateau region are highly dependent on pollinators for seed production (76.2% of seed production was contributed by animal pollinators and 44.6% of plants would produce no seed without pollinator visitation). Contrary to our expectation, there was no significant elevational gradient in pollinator dependence index. Although the pollinator dependence index was not significantly correlated with pollen limitation, flower size, floral longevity, or reward type, it was correlated with compatibility status and flowering time. These findings indicate that pollinator dependence does not decrease along an elevational gradient in the Qinghai-Tibet Plateau. Our study also highlights the severe vulnerability of flowering plant seed production to pollinator declines under global change in the Qinghai-Tibet Plateau region, particularly for early-flowering or self-incompatible plants growing at higher elevations (e.g., subnival belt).
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Affiliation(s)
- Yue-Wen Xu
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Lu Sun
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Rong Ma
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Yong-Qian Gao
- Yunnan Forestry Technological College, Kunming 650224, China
| | - Hang Sun
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Bo Song
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
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10
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Han EK, Tamaki I, Oh SH, Park JS, Cho WB, Jin DP, Kim BY, Yang S, Son DC, Choi HJ, Gantsetseg A, Isagi Y, Lee JH. Genetic and demographic signatures accompanying the evolution of the selfing syndrome in Daphne kiusiana, an evergreen shrub. ANNALS OF BOTANY 2023; 131:751-767. [PMID: 36469429 PMCID: PMC10184445 DOI: 10.1093/aob/mcac142] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/23/2022] [Indexed: 05/16/2023]
Abstract
BACKGROUND AND AIMS The evolution of mating systems from outcrossing to self-fertilization is a common transition in flowering plants. This shift is often associated with the 'selfing syndrome', which is characterized by less visible flowers with functional changes to control outcrossing. In most cases, the evolutionary history and demographic dynamics underlying the evolution of the selfing syndrome remain poorly understood. METHODS Here, we characterize differences in the demographic genetic consequences and associated floral-specific traits between two distinct geographical groups of a wild shrub, Daphne kiusiana, endemic to East Asia; plants in the eastern region (southeastern Korea and Kyushu, Japan) exhibit smaller and fewer flowers compared to those of plants in the western region (southwestern Korea). Genetic analyses were conducted using nuclear microsatellites and chloroplast DNA (multiplexed phylogenetic marker sequencing) datasets. KEY RESULTS A high selfing rate with significantly increased homozygosity characterized the eastern lineage, associated with lower levels of visibility and herkogamy in the floral traits. The two lineages harboured independent phylogeographical histories. In contrast to the western lineage, the eastern lineage showed a gradual reduction in the effective population size with no signs of a severe bottleneck despite its extreme range contraction during the last glacial period. CONCLUSIONS Our results suggest that the selfing-associated morphological changes in D. kiusiana are of relatively old origin (at least 100 000 years ago) and were driven by directional selection for efficient self-pollination. We provide evidence that the evolution of the selfing syndrome in D. kiusiana is not strongly associated with a severe population bottleneck.
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Affiliation(s)
- Eun-Kyeong Han
- Department of Biology Education, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Ichiro Tamaki
- Gifu Academy of Forest Science and Culture, 88 Sodai, Mino, Gifu 501-3714, Japan
| | - Sang-Hun Oh
- Department of Biology, Daejeon University, Daejeon 34520, Republic of Korea
| | - Jong-Soo Park
- Department of Botany, Honam National Institute of Biological Resources, Mokpo 58762, Republic of Korea
| | - Won-Bum Cho
- Department of Plant Variety Protection, National Forest Seed and Variety Center, Chungju 27495, Republic of Korea
| | - Dong-Pil Jin
- Urban Biodiversity Research Division, Sejong National Arboretum, Sejong 30106, Republic of Korea
| | - Bo-Yun Kim
- Plant Resources Division, National Institute of Biological Resources, Incheon 22689, Republic of Korea
| | - Sungyu Yang
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju 58245, Republic of Korea
| | - Dong Chan Son
- Division of Forest Biodiversity and Herbarium, Korea National Arboretum, Pocheon 11186, Republic of Korea
| | - Hyeok-Jae Choi
- Department of Biology and Chemistry, Changwon National University, Changwon 51140, Republic of Korea
| | - Amarsanaa Gantsetseg
- Department of Biology Education, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Yuji Isagi
- Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Jung-Hyun Lee
- Department of Biology Education, Chonnam National University, Gwangju 61186, Republic of Korea
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11
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Jia Y, Liu C, Li Y, Xiang Y, Pan Y, Liu Q, Gao S, Yin X, Wang Z. Inheritance of distyly and homostyly in self-incompatible Primula forbesii. Heredity (Edinb) 2023; 130:259-268. [PMID: 36788365 PMCID: PMC10076296 DOI: 10.1038/s41437-023-00598-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 02/02/2023] [Accepted: 02/02/2023] [Indexed: 02/16/2023] Open
Abstract
The evolutionary transition from self-incompatible distyly to self-compatible homostyly frequently occurs in heterostylous taxa. Although the inheritance of distyly and homostyly has been deeply studied, our understanding on modifications of the classical simple Mendelian model is still lacking. Primula forbesii, a biennial herb native to southwest China, is a typical distylous species, but after about 20 years of cultivation with open pollination, self-compatible homostyly appeared, providing ideal material for the study of the inheritance of distyly and homostyly. In this study, exogenous homobrassinolide was used to break the heteromorphic incompatibility of P. forbesii. Furthermore, we performed artificial pollination and open-pollination experiments to observe the distribution of floral morphs in progeny produced by different crosses. The viability of seeds from self-pollination was always the lowest among all crosses, and the homozygous S-morph plants (S/S) occurred in artificial pollination experiments but may experience viability selection. The distyly of P. forbesii is governed by a single S-locus, with S-morph dominant hemizygotes (S/-) and L-morph recessive homozygotes (-/-). Homostylous plants have a genotype similar to L-morph plants, and homostyly may be caused by one or more unlinked modifier genes outside the S-locus. Open pollinations confirm that autonomous self-pollination occurs frequently in L-morphs and homostylous plants. This study deepens the understanding of the inheritance of distyly and details a case of homostyly that likely originated from one or more modifier genes.
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Affiliation(s)
- Yin Jia
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China.
| | - Cailei Liu
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Yifeng Li
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Yuanfen Xiang
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Yuanzhi Pan
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Qinglin Liu
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Suping Gao
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Xiancai Yin
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
| | - Zexun Wang
- College of Landscape Architecture, Sichuan Agricultural University, Chengdu, China
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12
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Mora‐Carrera E, Stubbs RL, Keller B, Léveillé‐Bourret É, de Vos JM, Szövényi P, Conti E. Different molecular changes underlie the same phenotypic transition: Origins and consequences of independent shifts to homostyly within species. Mol Ecol 2023; 32:61-78. [PMID: 34761469 PMCID: PMC10078681 DOI: 10.1111/mec.16270] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 12/29/2022]
Abstract
The repeated transition from outcrossing to selfing is a key topic in evolutionary biology. However, the molecular basis of such shifts has been rarely examined due to lack of knowledge of the genes controlling these transitions. A classic example of mating system transition is the repeated shift from heterostyly to homostyly. Occurring in 28 angiosperm families, heterostyly is characterized by the reciprocal position of male and female sexual organs in two (or three) distinct, usually self-incompatible floral morphs. Conversely, homostyly is characterized by a single, self-compatible floral morph with reduced separation of male and female organs, facilitating selfing. Here, we investigate the origins of homostyly in Primula vulgaris and its microevolutionary consequences by integrating surveys of the frequency of homostyles in natural populations, DNA sequence analyses of the gene controlling the position of female sexual organs (CYPᵀ), and microsatellite genotyping of both progeny arrays and natural populations characterized by varying frequencies of homostyles. As expected, we found that homostyles displace short-styled individuals, but long-style morphs are maintained at low frequencies within populations. We also demonstrated that homostyles repeatedly evolved from short-styled individuals in association with different types of loss-of-function mutations in CYPᵀ. Additionally, homostyly triggers a shift to selfing, promoting increased inbreeding within and genetic differentiation among populations. Our results elucidate the causes and consequences of repeated transitions to homostyly within species, and the putative mechanisms precluding its fixation in P. vulgaris. This study represents a benchmark for future analyses of losses of heterostyly in other angiosperms.
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Affiliation(s)
- Emiliano Mora‐Carrera
- Department of Systematic and Evolutionary BotanyUniversity of ZurichZurichSwitzerland
| | - Rebecca L. Stubbs
- Department of Systematic and Evolutionary BotanyUniversity of ZurichZurichSwitzerland
| | - Barbara Keller
- Department of Systematic and Evolutionary BotanyUniversity of ZurichZurichSwitzerland
| | - Étienne Léveillé‐Bourret
- Department of Systematic and Evolutionary BotanyUniversity of ZurichZurichSwitzerland
- Département de Sciences BiologiquesInstitut de Recherche en Biologie VégétaleUniversité de MontréalMontréalQuébecCanada
| | - Jurriaan M. de Vos
- Department of Environmental Sciences – BotanyUniversity of BaselBaselSwitzerland
| | - Peter Szövényi
- Department of Systematic and Evolutionary BotanyUniversity of ZurichZurichSwitzerland
| | - Elena Conti
- Department of Systematic and Evolutionary BotanyUniversity of ZurichZurichSwitzerland
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13
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Yi H, Wang J, Wang J, Rausher M, Kang M. Genomic insights into inter- and intraspecific mating system shifts in Primulina. Mol Ecol 2022; 31:5699-5713. [PMID: 36178058 DOI: 10.1111/mec.16706] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 08/17/2022] [Accepted: 09/21/2022] [Indexed: 01/13/2023]
Abstract
The mating system shift from outcrossing to selfing is one of the most frequent evolutionary trends in flowering plants. However, the genomic consequences of this shift remain poorly understood. Specifically, the relative importance of the demographic and genetic processes causing changes in genetic variation and selection efficacy associated with the evolution of selfing is unclear. Here we sequenced the genomes of two Primulina species with contrasting mating systems: P. eburnea (outcrossing) versus P. tabacum (outcrossing, mixed-mating and selfing populations). Whole-genome resequencing data were used to investigate the genomic consequences of mating system shifts within and between species. We found that highly selfing populations of P. tabacum display loss of genetic diversity, increased deleterious mutations, higher genomic burden and fewer adaptive substitutions. However, compared with outcrossing populations, mixed-mating populations did not display loss of genetic diversity and accumulation of genetic load. We find no evidence of population bottlenecks associated with the shift to selfing, which suggests that the genetic effects of selfing on Ne and possibly linked selection, rather than demographic history, are the primary drivers of diversity reduction in highly selfing populations. Our results highlight the importance of distinguishing the relative contribution of mating system and demography on the genomic consequences associated with mating system evolution in plants.
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Affiliation(s)
- Huiqin Yi
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jieyu Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Jing Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Mark Rausher
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Ming Kang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
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14
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Liu C, Jia Y, Li Y, Xiang Y, Pan Y, Liu Q, Ma K, Yin X. The rapid appearance of homostyly in a cultivated distylous population of Primula forbesii. Ecol Evol 2022; 12:e9515. [PMID: 36415874 PMCID: PMC9674475 DOI: 10.1002/ece3.9515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 10/22/2022] [Accepted: 10/26/2022] [Indexed: 11/20/2022] Open
Abstract
Evolutionary breakdown from rigorous outbreeding to self-fertilization frequently occurs in angiosperms. Since the pollinators are not necessary, self-compatible populations often reduce investment in floral display characteristics and pollination reward. Primula forbesii is a biennial herb with distribution restricted to southwest China; it was initially a self-incompatible distylous species, but after 20 years of artificial domestication, homostyly appeared. This change in style provides an ideal material to explore the time required for plant mating systems to adapt to new environmental changes and test whether flower attraction has reduced following transitions to selfing. We did a survey in wild populations of P. forbesii where its seeds were originally collected 20 years ago and recorded the floral morph frequencies and morphologies. The floral morphologies, self-incompatibility, floral scent, and pollinator visitation between distyly and homostyly were compared in greenhouse. Floral morph frequencies of wild populations did not change, while the cultivated population was inclined to L-morph and produced homostyly. Evidence from stigma papillae and pollen size supports the hypothesis that the homostyly possibly originated from mutations of large effect genes in distylous linkage region. Transitions to self-compatible homostyly are accompanied by smaller corolla size, lower amounts of terpenoids, especially linalool and higher amounts of fatty acid derivatives. The main pollinators in the greenhouse were short-tongued Apis cerana. However, homostyly had reduced visiting frequency. The mating system of P. forbesii changed rapidly in just about 20 years of domestication, and our findings confirm the hypothesis that the transition to selfing is accompanied by decreased flower attraction.
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Affiliation(s)
- Cai‐Lei Liu
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
| | - Yin Jia
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
| | - Yi‐Feng Li
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
| | - Yuan‐Fen Xiang
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
| | - Yuan‐Zhi Pan
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
| | - Qing‐Lin Liu
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
| | - Ke‐Hang Ma
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
| | - Xian‐Cai Yin
- College of Landscape ArchitectureSichuan Agricultural UniversityChengduChina
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15
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Tackett M, Berg C, Simmonds T, Lopez O, Brown J, Ruggiero R, Weber J. Breeding system and geospatial variation shape the population genetics of Triodanis perfoliata. Ecol Evol 2022; 12:e9382. [PMID: 36248672 PMCID: PMC9547245 DOI: 10.1002/ece3.9382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 08/25/2022] [Accepted: 09/09/2022] [Indexed: 11/21/2022] Open
Abstract
Both intrinsic and extrinsic forces work together to shape connectivity and genetic variation in populations across the landscape. Here we explored how geography, breeding system traits, and environmental factors influence the population genetic patterns of Triodanis perfoliata, a widespread mix-mating annual plant in the contiguous US. By integrating population genomic data with spatial analyses and modeling the relationship between a breeding system and genetic diversity, we illustrate the complex ways in which these forces shape genetic variation. Specifically, we used 4705 single nucleotide polymorphisms to assess genetic diversity, structure, and evolutionary history among 18 populations. Populations with more obligately selfing flowers harbored less genetic diversity (π: R 2 = .63, p = .01, n = 9 populations), and we found significant population structuring (F ST = 0.48). Both geographic isolation and environmental factors played significant roles in predicting the observed genetic diversity: we found that corridors of suitable environments appear to facilitate gene flow between populations, and that environmental resistance is correlated with increased genetic distance between populations. Last, we integrated our genetic results with species distribution modeling to assess likely patterns of connectivity among our study populations. Our landscape and evolutionary genetic results suggest that T. perfoliata experienced a complex demographic and evolutionary history, particularly in the center of its distribution. As such, there is no singular mechanism driving this species' evolution. Together, our analyses support the hypothesis that the breeding system, geography, and environmental variables shape the patterns of diversity and connectivity of T. perfoliata in the US.
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Affiliation(s)
- Morgan Tackett
- Neuroscience Graduate ProgramUniversity of Oklahoma Health Sciences CenterOklahoma CityOklahomaUSA
| | - Colette Berg
- Division of Biological SciencesUniversity of MontanaMissoulaMontanaUSA
| | - Taylor Simmonds
- School of Biological SciencesSouthern Illinois University, CarbondaleCarbondaleIllinoisUSA
| | - Olivia Lopez
- Department of BiologySoutheast Missouri State UniversityCape GirardeauMissouriUSA
| | - Jason Brown
- School of Biological SciencesSouthern Illinois University, CarbondaleCarbondaleIllinoisUSA
| | - Robert Ruggiero
- Department of BiologySoutheast Missouri State UniversityCape GirardeauMissouriUSA
| | - Jennifer Weber
- School of Biological SciencesSouthern Illinois University, CarbondaleCarbondaleIllinoisUSA
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16
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Silva DM, Luna ALL, Souza CS, Nunes YRF, Fonseca RS, Azevedo IFPD. Sexual and reproductive systems of woody species in
vereda
are distributed according to the life form and habitat occurrence. AUSTRAL ECOL 2022. [DOI: 10.1111/aec.13235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Danila Moreira Silva
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
| | - Andressa Laís Lacerda Luna
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
| | - Camila Silveira Souza
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
- Laboratório de Ecologia Vegetal, Departamento de Biologia Geral Universidade Estadual de Montes Claros Montes Claros Brazil
| | - Yule Roberta Ferreira Nunes
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
- Laboratório de Ecologia Vegetal, Departamento de Biologia Geral Universidade Estadual de Montes Claros Montes Claros Brazil
| | - Rúbia Santos Fonseca
- Instituto de Ciências Agrárias Universidade Federal de Minas Gerais, Bairro Universitário Montes Claros Brazil
| | - Islaine Franciely Pinheiro de Azevedo
- Programa de Pós‐Graduação em Botânica Aplicada Universidade Estadual de Montes Claros Avenida Dr. Ruy Braga, S/N – Bairro Vila Mauricéia Montes Claros 39401‐089 Brazil
- Laboratório de Ecologia Vegetal, Departamento de Biologia Geral Universidade Estadual de Montes Claros Montes Claros Brazil
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17
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Fonseca CR, Gossner MM, Kollmann J, Brändle M, Paterno GB. Insect herbivores drive sex allocation in angiosperm flowers. Ecol Lett 2022; 25:2177-2188. [PMID: 35953880 DOI: 10.1111/ele.14092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 07/14/2022] [Accepted: 07/26/2022] [Indexed: 11/29/2022]
Abstract
Why sex has evolved and is maintained is an open question in evolutionary biology. The Red Queen hypothesis predicts that host lineages subjected to more intense parasite pressure should invest more in sexual reproduction to continuously create novel defences against their rapidly evolving natural enemies. In this comparative study across the angiosperms, we show that hermaphrodite plant species associated with higher species richness of insect herbivores evolved flowers with higher biomass allocation towards the male sex, an indication of their greater outcrossing effort. This pattern remained robust after controlling for key vegetative, reproductive and biogeographical traits, suggesting that long-term herbivory pressure is a key factor driving the selfing-outcrossing gradient of higher plants. Although flower evolution is frequently associated with mutualistic pollinators, our findings support the Red Queen hypothesis and suggest that insect herbivores drive the sexual strategies of flowering plants and their genetic diversity.
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Affiliation(s)
| | - Martin M Gossner
- Forest Entomology, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland.,ETH Zurich, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, Zurich, Switzerland.,Chair of Terrestrial Ecology, School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Johannes Kollmann
- Chair of Restoration Ecology, School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Martin Brändle
- Animal Ecology, Faculty of Biology, Department of Ecology, Philipps Universität Marburg, Marburg, Germany
| | - Gustavo Brant Paterno
- Departamento de Ecologia, Universidade Federal do Rio Grande do Norte, Natal, Brazil.,Chair of Restoration Ecology, School of Life Sciences, Technical University of Munich, Freising, Germany
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18
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Passer AR, Clancey SA, Shea T, David-Palma M, Averette AF, Boekhout T, Porcel BM, Nowrousian M, Cuomo CA, Sun S, Heitman J, Coelho MA. Obligate sexual reproduction of a homothallic fungus closely related to the Cryptococcus pathogenic species complex. eLife 2022; 11:e79114. [PMID: 35713948 PMCID: PMC9296135 DOI: 10.7554/elife.79114] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/15/2022] [Indexed: 12/03/2022] Open
Abstract
Fungi are enigmatic organisms that flourish in soil, on decaying plants, or during infection of animals or plants. Growing in myriad forms, from single-celled yeast to multicellular molds and mushrooms, fungi have also evolved a variety of strategies to reproduce. Normally, fungi reproduce in one of two ways: either they reproduce asexually, with one individual producing a new individual identical to itself, or they reproduce sexually, with two individuals of different 'mating types' contributing to produce a new individual. However, individuals of some species exhibit 'homothallism' or self-fertility: these individuals can produce reproductive cells that are universally compatible, and therefore can reproduce sexually with themselves or with any other cell in the population. Homothallism has evolved multiple times throughout the fungal kingdom, suggesting it confers advantage when population numbers are low or mates are hard to find. Yet some homothallic fungi been overlooked compared to heterothallic species, whose mating types have been well characterised. Understanding the genetic basis of homothallism and how it evolved in different species can provide insights into pathogenic species that cause fungal disease. With that in mind, Passer, Clancey et al. explored the genetic basis of homothallism in Cryptococcus depauperatus, a close relative of C. neoformans, a species that causes fungal infections in humans. A combination of genetic sequencing techniques and experiments were applied to analyse, compare, and manipulate C. depauperatus' genome to see how this species evolved self-fertility. Passer, Clancey et al. showed that C. depauperatus evolved the ability to reproduce sexually by itself via a unique evolutionary pathway. The result is a form of homothallism never reported in fungi before. C. depauperatus lost some of the genes that control mating in other species of fungi, and acquired genes from the opposing mating types of a heterothallic ancestor to become self-fertile. Passer, Clancey et al. also found that, unlike other Cryptococcus species that switch between asexual and sexual reproduction, C. depauperatus grows only as long, branching filaments called hyphae, a sexual form. The species reproduces sexually with itself throughout its life cycle and is unable to produce a yeast (asexual) form, in contrast to other closely related species. This work offers new insights into how different modes of sexual reproduction have evolved in fungi. It also provides another interesting case of how genome plasticity and evolutionary pressures can produce similar outcomes, homothallism, via different evolutionary paths. Lastly, assembling the complete genome of C. depauperatus will foster comparative studies between pathogenic and non-pathogenic Cryptococcus species.
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Affiliation(s)
- Andrew Ryan Passer
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Shelly Applen Clancey
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Terrance Shea
- Broad Institute of MIT and HarvardCambridgeUnited States
| | - Márcia David-Palma
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Anna Floyd Averette
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Teun Boekhout
- Westerdijk Fungal Biodiversity InstituteUtrechtNetherlands
- Institute of Biodiversity and Ecosystem Dynamics (IBED), University of AmsterdamAmsterdamNetherlands
| | - Betina M Porcel
- Génomique Métabolique, CNRS, University Evry, Université Paris-SaclayEvryFrance
| | - Minou Nowrousian
- Lehrstuhl für Molekulare und Zelluläre Botanik, Ruhr-Universität BochumBochumGermany
| | | | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Marco A Coelho
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
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19
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Martins Junior ER, da Costa ACG, Milet-Pinheiro P, Navarro D, Thomas WW, Giulietti AM, Machado IC. Mixed pollination system and floral signals of Paepalanthus (Eriocaulaceae): insects and geitonogamy ensure high reproductive success. ANNALS OF BOTANY 2022; 129:473-484. [PMID: 35039823 PMCID: PMC8944716 DOI: 10.1093/aob/mcac008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 01/14/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND AND AIMS Eriocaulaceae exhibit a great variety of floral traits associated with insect (e.g. nectariferous structures) and wind pollination (unisexual flowers, exposed sexual organs and small pollen grains), as well as the 'selfing syndrome' (small flowers, short distance between stigma and anthers, and temporal overlap of male and female phases). Paepalanthus bifidus, P. subtilis and P. tortilis are related species that differ in form, size and colour of floral structures. We aimed to investigate the pollination and reproductive biology of these three species. METHODS We analysed the floral biology, floral visitors, pollinator behaviour, and the contribution of insects, wind and spontaneous geitonogamy to fruit set. We also evaluated the floral colour and scent of the species. Colour reflectance of capitula of each species was measured and plotted in models of insect vision. Floral scent samples were extracted and the compounds were compared to vegetative scent samples. KEY RESULTS In all species, the staminate and pistillate flowers are arranged in alternating cycles with a temporal overlap between these phases. Ants were the most frequent floral visitors and were effective pollinators in P. bifidus and P. tortilis, while flies were occasional pollinators in P. tortilis. Floral visitors were not observed in P. subtilis. In all species, fruits were produced by spontaneous geitonogamy, with no evidence of wind pollination. According to the models of insect vision, the colours of the capitula of P. bifidus and P. subtilis are the most inconspicuous for ants and flies. We found no difference between the emission of volatiles of inflorescences and vegetative structures. CONCLUSIONS This study suggests that ant pollination might be more widespread in Eriocaulaceae than currently assumed. Furthermore, for small monocarpic plants, mixed mating strategies are most favourable, by ensuring reproduction either by outcrossing when pollinators are abundant or by spontaneous geitonogamy when pollinations are scarce/absent.
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Affiliation(s)
- Edivaldo Rodrigues Martins Junior
- Programa de Pós-Graduação em Biologia Vegetal, Departamento de Botânica, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Ana Carolina Galindo da Costa
- Programa de Pós-Graduação em Biologia Vegetal, Departamento de Botânica, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
- Instituto Tecnológico Vale, Belém, Pará, Brazil
| | | | - Daniela Navarro
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | | | - Ana Maria Giulietti
- Universidade Estadual de Feira de Santana, Programa de Pós-Graduação em Botânica, Feria de Santana, Bahia, Brazil
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20
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Pretz C, Smith SD. Intraspecific breakdown of self-incompatibility in Physalis acutifolia (Solanaceae). AOB PLANTS 2022; 14:plab080. [PMID: 35079331 PMCID: PMC8783618 DOI: 10.1093/aobpla/plab080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/21/2021] [Indexed: 05/13/2023]
Abstract
Variation in mating systems is prevalent throughout angiosperms, with many transitions between outcrossing and selfing above and below the species level. This study documents a new case of an intraspecific breakdown of self-incompatibility in a wild relative of tomatillo, Physalis acutifolia. We used controlled greenhouse crosses to identify self-incompatible (SI) and self-compatible (SC) individuals grown from seed sampled across seven sites across Arizona and New Mexico. We measured 14 flower and fruit traits to test for trait variation associated with mating system. We also quantified pollen tube growth in vivo and tested for the presence of the S-RNase proteins in SI and SC styles. We found that seed from six of the seven sites produced SI individuals that terminated self-pollen tubes in the style and showed detectable S-RNase expression. By contrast, seed from one Arizona site produced SC individuals with no S-RNase expression. These SC individuals displayed typical selfing-syndrome traits such as smaller corollas, reduced stigma-anther distances, and a smaller pollen-ovule ratio. We also found plasticity in self-incompatibility as most of the SI individuals became SC and lost S-RNase expression roughly after 6 months in the greenhouse. While fixed differences in mating systems are known among the SI wild species and the often SC domesticated tomatillos, our study is the first to demonstrate intraspecific variation in natural populations as well as variation in SI over an individual's lifespan.
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Affiliation(s)
- Chelsea Pretz
- Department of Ecology and Evolutionary Biology, University of Colorado, 1900 Pleasant Street, Boulder, CO 80309, USA
- Corresponding author’s e-mail address:
| | - Stacey D Smith
- Department of Ecology and Evolutionary Biology, University of Colorado, 1900 Pleasant Street, Boulder, CO 80309, USA
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21
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McElderry RM, Spigler RB, Vogler DW, Kalisz S. How early does the selfing syndrome arise? Associations between selfing ability and flower size within populations of the mixed-mater Collinsia verna. AMERICAN JOURNAL OF BOTANY 2022; 109:333-344. [PMID: 34778956 PMCID: PMC9305746 DOI: 10.1002/ajb2.1804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/08/2021] [Accepted: 11/08/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Widespread associations between selfing rate and floral size within and among taxa suggest that these traits may evolve in concert. Does this association develop immediately because of shared genetic and/or developmental control, or stepwise with selection shaping the evolution of one trait following the other? If the former, then association ought to appear within and across selfing populations. We explore this fundamental question in three populations of the mixed-mater Collinsia verna where autonomous selfing (AS) ability has been shown to be under selection by the pollination environment. METHODS We grew clonal replicates of C. verna in a controlled environment to characterize broad-sense genetic correlations among traits within populations and to assess whether divergence in mating system and floral traits among these populations is consistent with their previously observed selection pressures. RESULTS As predicted by their respective pollination environments, we demonstrate significant genetic divergence among populations in AS ability. However, patterns of divergence in floral traits (petal, stamen, and style size, stigmatic receptivity, and stigma-anther distance) were not as expected. Within populations, genetic variation in AS appeared largely independent from floral traits, except for a single weak negative association in one population between flower size and AS rate. CONCLUSIONS Together, these results suggest that associations between selfing rate and floral traits across Collinsia species are not reflected at microevolutionary scales. If C. verna were to continue evolving toward the selfing syndrome, floral trait evolution would likely follow stepwise from mating system evolution.
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Affiliation(s)
- Robert M. McElderry
- Department of Ecology and Evolutionary BiologyUniversity of Tennessee KnoxvilleKnoxvilleTennesseeUSA
| | | | | | - Susan Kalisz
- Department of Ecology and Evolutionary BiologyUniversity of Tennessee KnoxvilleKnoxvilleTennesseeUSA
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22
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Broz AK, Miller CM, Baek YS, Tovar-Méndez A, Acosta-Quezada PG, Riofrío-Cuenca TE, Rusch DB, Bedinger PA. S-RNase Alleles Associated With Self-Compatibility in the Tomato Clade: Structure, Origins, and Expression Plasticity. Front Genet 2021; 12:780793. [PMID: 34938321 PMCID: PMC8685505 DOI: 10.3389/fgene.2021.780793] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/09/2021] [Indexed: 11/13/2022] Open
Abstract
The self-incompatibility (SI) system in the Solanaceae is comprised of cytotoxic pistil S-RNases which are countered by S-locus F-box (SLF) resistance factors found in pollen. Under this barrier-resistance architecture, mating system transitions from SI to self-compatibility (SC) typically result from loss-of-function mutations in genes encoding pistil SI factors such as S-RNase. However, the nature of these mutations is often not well characterized. Here we use a combination of S-RNase sequence analysis, transcript profiling, protein expression and reproductive phenotyping to better understand different mechanisms that result in loss of S-RNase function. Our analysis focuses on 12 S-RNase alleles identified in SC species and populations across the tomato clade. In six cases, the reason for gene dysfunction due to mutations is evident. The six other alleles potentially encode functional S-RNase proteins but are typically transcriptionally silenced. We identified three S-RNase alleles which are transcriptionally silenced under some conditions but actively expressed in others. In one case, expression of the S-RNase is associated with SI. In another case, S-RNase expression does not lead to SI, but instead confers a reproductive barrier against pollen tubes from other tomato species. In the third case, expression of S-RNase does not affect self, interspecific or inter-population reproductive barriers. Our results indicate that S-RNase expression is more dynamic than previously thought, and that changes in expression can impact different reproductive barriers within or between natural populations.
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Affiliation(s)
- Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, CO, United States
| | - Christopher M Miller
- Department of Biology, Colorado State University, Fort Collins, CO, United States
| | - You Soon Baek
- Department of Biology, Colorado State University, Fort Collins, CO, United States
| | | | | | | | - Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, United States
| | - Patricia A Bedinger
- Department of Biology, Colorado State University, Fort Collins, CO, United States
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23
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Prior CJ, Busch JW. Selfing rate variation within species is unrelated to life-history traits or geographic range position. AMERICAN JOURNAL OF BOTANY 2021; 108:2294-2308. [PMID: 34632564 DOI: 10.1002/ajb2.1766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 08/25/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
PREMISE In plants, populations and species vary widely along the continuum from outcrossing to selfing. Life-history traits and ecological circumstances influence among-species variation in selfing rates, but their general role in explaining intraspecific variation is unknown. Using a database of plant species, we test whether life-history traits, geographic range position, or abundance predict selfing rate variation among populations. METHODS We identified species where selfing rates were estimated in at least three populations at known locations. Two key life-history traits (generation time and growth form) were used to predict within-species selfing rate variation. Populations sampled within a species' native range were assessed for proximity to the nearest edge and abundance. Finally, we conducted linear and segmented regressions to determine functional relationships between selfing rate and geographic range position within species. RESULTS Selfing rates for woody species varied less than for herbs, which is explained by the lower average selfing rate of woody species. Relationships between selfing and peripherality or abundance significantly varied among species in their direction and magnitude. However, there was no general pattern of increased selfing toward range edges. A power analysis shows that tests of this hypothesis require studying many (i.e., 40+) populations. CONCLUSIONS Intraspecific variation in plant mating systems is often substantial yet remains difficult to explain. Beyond sampling more populations, future tests of biogeographic hypotheses will benefit from phylogeographic information concerning specific range edges, the study of traits influencing mating system (e.g., herkogamy), and measures of abundance at local scales (e.g., population density).
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Affiliation(s)
- Carly J Prior
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
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24
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Delgado-Dávila R, Martén-Rodríguez S. A test of the reproductive assurance hypothesis in Ipomoea hederacea: does inbreeding depression counteract the benefits of self-pollination? AMERICAN JOURNAL OF BOTANY 2021; 108:2162-2173. [PMID: 34786691 DOI: 10.1002/ajb2.1794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 07/15/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Darwin proposed that self-pollination in allegedly outcrossing species might act as a reproductive assurance mechanism when pollinators or mates are scarce; however, in natural populations, the benefits of selfing may be opposed by seed discounting and inbreeding depression. While empirical studies show variation among species and populations in the magnitude of reproductive assurance, little is known about the counterbalancing effects of inbreeding depression. METHODS By comparing the female reproductive success of emasculated and open-pollinated flowers, we assessed the reproductive assurance hypothesis in two Mexican populations of Ipomoea hederacea. In one population, we assessed temporal variation in reproductive assurance for three years. We evaluated inbreeding depression on seed production, seedling germination, and dry plant mass by contrasting self- and cross-hand pollination treatments in one population for two years. RESULT The contribution of self-pollination to female reproductive success was high and consistent between populations, but there was variation in reproductive assurance across years. Inbreeding depression was absent in the early stages of progeny development, but there was a small negative effect of inbreeding in the probability of germination and the mass of adult progeny. CONCLUSIONS Self-pollination provided significant reproductive assurance in I. hederacea but this contribution was variable across time. The contribution of reproductive assurance is probably reduced by inbreeding depression in later stages of progeny development, but this counter effect was small in the study populations. This study supports the hypothesis that reproductive assurance with limited inbreeding depression is likely an important selective force in the evolution of self-pollination in the genus Ipomoea.
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Affiliation(s)
- Ruth Delgado-Dávila
- Universitat Autònoma de Barcelona, Cerdanyola del Vallès, 08193, Spain
- Laboratorio Nacional de Análisis y Síntesis Ecológica, Escuela Nacional de Estudios Superiores, unidad Morelia, Universidad Nacional Autónoma de México, 58089, Morelia, Michoacán, México
| | - Silvana Martén-Rodríguez
- Laboratorio Nacional de Análisis y Síntesis Ecológica, Escuela Nacional de Estudios Superiores, unidad Morelia, Universidad Nacional Autónoma de México, 58089, Morelia, Michoacán, México
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25
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Heywood JS, Smith SA. DOES CLEISTOGAMOUS SELF-FERTILIZATION PROVIDE REPRODUCTIVE ASSURANCE AGAINST SEED PREDATION IN RUELLIA HUMILIS? SOUTHWEST NAT 2021. [DOI: 10.1894/0038-4909-65.2.116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- John S. Heywood
- Department of Biology, Missouri State University, Springfield, MO 65897 (JSH, SAS)
| | - Stephanie A. Smith
- Department of Biology, Missouri State University, Springfield, MO 65897 (JSH, SAS)
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26
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Gorman CE, Li Y, Dorken ME, Stift M. No evidence for incipient speciation by selfing in North American Arabidopsis lyrata. J Evol Biol 2021; 34:1397-1405. [PMID: 34228843 DOI: 10.1111/jeb.13901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/01/2021] [Accepted: 07/03/2021] [Indexed: 01/01/2023]
Abstract
Self-fertilization inherently restricts gene flow by reducing the fraction of offspring that can be produced by inter-population matings. Therefore, mating system transitions from outcrossing to selfing could result in reproductive isolation between selfing and outcrossing lineages and provide a starting point for speciation. In newly diverged lineages, for example after a transition to selfing, further reproductive isolation can be caused by a variety of prezygotic and post-zygotic mechanisms that operate before, during and after pollination. In animals, prezygotic barriers tend to evolve faster than post-zygotic ones. This is not necessarily the case for plants, for which the relative importance of post-mating, post-fertilization and early-acting post-zygotic barriers has been investigated far less. To test whether post-pollination isolation exists between populations of North American Arabidopsis lyrata that differ in breeding (self-incompatible versus self-compatible) and mating system (outcrossing versus selfing), we compared patterns of seed set after crosses made within populations, between populations of the same mating system and between populations with different mating systems. We found no evidence for post-pollination isolation between plants from selfing populations (self-compatible, low outcrossing rates) and outcrossing populations (self-incompatible, high outcrossing rates) via either prezygotic or early-acting post-zygotic mechanisms. Together with the results of other studies indicating the absence of reproductive barriers acting before and during pollination, we conclude that the transition to selfing in this study system has not led to the formation of reproductive barriers between selfing and outcrossing populations of North American A. lyrata.
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Affiliation(s)
| | - Yan Li
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
| | - Marcel E Dorken
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Marc Stift
- Department of Biology, University of Konstanz, Konstanz, Germany
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27
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Broz AK, Simpson-Van Dam A, Tovar-Méndez A, Hahn MW, McClure B, Bedinger PA. Spread of self-compatibility constrained by an intrapopulation crossing barrier. THE NEW PHYTOLOGIST 2021; 231:878-891. [PMID: 33864700 DOI: 10.1111/nph.17400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 04/09/2021] [Indexed: 06/12/2023]
Abstract
Mating system transitions from self-incompatibility (SI) to self-compatibility (SC) are common in plants. In the absence of high levels of inbreeding depression, SC alleles are predicted to spread due to transmission advantage and reproductive assurance. We characterized mating system and pistil-expressed SI factors in 20 populations of the wild tomato species Solanum habrochaites from the southern half of the species range. We found that a single SI to SC transition is fixed in populations south of the Rio Chillon valley in central Peru. In these populations, SC correlated with the presence of the hab-6 S-haplotype that encodes a low activity S-RNase protein. We identified a single population segregating for SI/SC and hab-6. Intrapopulation crosses showed that hab-6 typically acts in the expected codominant fashion to confer SC. However, we found one specific S-haplotype (hab-10) that consistently rejects pollen of the hab-6 haplotype, and results in SI hab-6/hab-10 heterozygotes. We suggest that the hab-10 haplotype could act as a genetic mechanism to stabilize mixed mating in this population by presenting a disadvantage for the hab-6 haplotype. This barrier may represent a mechanism allowing for the persistence of SI when an SC haplotype appears in or invades a population.
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Affiliation(s)
- Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, CO, 80523-1878, USA
| | | | | | - Matthew W Hahn
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
- Department of Computer Science, Indiana University, Bloomington, IN, 47405, USA
| | - Bruce McClure
- Department of Biochemistry, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Patricia A Bedinger
- Department of Biology, Colorado State University, Fort Collins, CO, 80523-1878, USA
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28
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Van Rossum F, Raspé O, Vandelook F. Evidence of spontaneous selfing and disomic inheritance in Geranium robertianum. Ecol Evol 2021; 11:8640-8653. [PMID: 34257920 PMCID: PMC8258199 DOI: 10.1002/ece3.7677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/24/2021] [Accepted: 04/27/2021] [Indexed: 11/18/2022] Open
Abstract
Knowing species' breeding system and mating processes occurring in populations is important not only for understanding population dynamics, gene flow processes, and species' response to climate change, but also for designing control plans of invasive species. Geranium robertianum, a widespread biennial herbaceous species showing high morphological variation and wide ecological amplitude, can become invasive outside its distribution range. A mixed-mating system may be expected given the species' floral traits. However, autonomous selfing is considered as a common feature. Genetic variation and structure, and so population mating processes, have not been investigated in wild populations. We developed 15 polymorphic microsatellite markers to quantify genetic variation and structure in G. robertianum. To investigate whether selfing might be the main mating process in natural conditions, we sampled three generations of plants (adult, F1, and F2) for populations from the UK, Spain, Belgium, Germany, and Sweden, and compared open-pollinated with outcrossed hand-pollinated F2 progeny. The highly positive Wright's inbreeding coefficient (F IS) values in adults, F1, and open-pollinated F2 progeny and the low F IS values in outcross F2 progeny supported autonomous selfing as the main mating process for G. robertianum in wild conditions, despite the presence of attractive signals for insect pollination. Genetic differentiation among samples was found, showing some western-eastern longitudinal trend. Long-distance seed dispersal might have contributed to the low geographic structure. Local genetic differentiation may have resulted not only from genetic drift effects favored by spontaneous selfing, but also from ecological adaptation. The presence of duplicate loci with disomic inheritance is consistent with the hypothesis of allotetraploid origin of G. robertianum. The fact that most microsatellite markers behave as diploid loci with no evidence of duplication supports the hypothesis of ancient polyploidization. The differences in locus duplication and the relatively high genetic diversity across G. robertianum range despite spontaneous autonomous selfing suggest multiple events of polyploidization.
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Affiliation(s)
- Fabienne Van Rossum
- Meise Botanic GardenMeiseBelgium
- Service général de l'Enseignement supérieur et de la Recherche scientifiqueFédération Wallonie‐BruxellesBrusselsBelgium
| | - Olivier Raspé
- Meise Botanic GardenMeiseBelgium
- Service général de l'Enseignement supérieur et de la Recherche scientifiqueFédération Wallonie‐BruxellesBrusselsBelgium
- Present address:
School of ScienceMae Fah Luang UniversityChiang RaiThailand
| | - Filip Vandelook
- Meise Botanic GardenMeiseBelgium
- Biology DepartmentPhilipps Universität MarburgMarburgGermany
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29
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Wang XJ, Barrett SCH, Zhong L, Wu ZK, Li DZ, Wang H, Zhou W. The Genomic Selfing Syndrome Accompanies the Evolutionary Breakdown of Heterostyly. Mol Biol Evol 2021; 38:168-180. [PMID: 32761213 PMCID: PMC7782863 DOI: 10.1093/molbev/msaa199] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The evolutionary transition from outcrossing to selfing can have important genomic consequences. Decreased effective population size and the reduced efficacy of selection are predicted to play an important role in the molecular evolution of the genomes of selfing species. We investigated evidence for molecular signatures of the genomic selfing syndrome using 66 species of Primula including distylous (outcrossing) and derived homostylous (selfing) taxa. We complemented our comparative analysis with a microevolutionary study of P. chungensis, which is polymorphic for mating system and consists of both distylous and homostylous populations. We generated chloroplast and nuclear genomic data sets for distylous, homostylous, and distylous–homostylous species and identified patterns of nonsynonymous to synonymous divergence (dN/dS) and polymorphism (πN/πS) in species or lineages with contrasting mating systems. Our analysis of coding sequence divergence and polymorphism detected strongly reduced genetic diversity and heterozygosity, decreased efficacy of purifying selection, purging of large-effect deleterious mutations, and lower rates of adaptive evolution in samples from homostylous compared with distylous populations, consistent with theoretical expectations of the genomic selfing syndrome. Our results demonstrate that self-fertilization is a major driver of molecular evolutionary processes with genomic signatures of selfing evident in both old and relatively young homostylous populations.
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Affiliation(s)
- Xin-Jia Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.,Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Li Zhong
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Zhi-Kun Wu
- Department of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, Guizhou, China
| | - De-Zhu Li
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.,Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Hong Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Wei Zhou
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.,Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
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30
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Camus C, Solas M, Martínez C, Vargas J, Garcés C, Gil-Kodaka P, Ladah LB, Serrão EA, Faugeron S. Mates Matter: Gametophyte Kinship Recognition and Inbreeding in the Giant Kelp, Macrocystis pyrifera (Laminariales, Phaeophyceae). JOURNAL OF PHYCOLOGY 2021; 57:711-725. [PMID: 33583038 DOI: 10.1111/jpy.13146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/22/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
Inbreeding, the mating between genetically related individuals, often results in reduced survival and fecundity of offspring, relative to outcrossing. Yet, high inbreeding rates are commonly observed in seaweeds, suggesting compensatory reproductive traits may affect the costs and benefits of the mating system. We experimentally manipulated inbreeding levels in controlled crossing experiments, using gametophytes from 19 populations of Macrocystis pyrifera along its Eastern Pacific coastal distribution (EPC). The objective was to investigate the effects of male-female kinship on female fecundity and fertility, to estimate inbreeding depression in the F1 progeny, and to assess the variability of these effects among different regions and habitats of the EPC. Results revealed that the presence and kinship of males had a significant effect on fecundity and fertility of female gametophytes. Females left alone or in the presence of sibling males express the highest gametophyte size, number, and size of oogonia, suggesting they were able to sense the presence and the identity of their mates before gamete contact. The opposite trend was observed for the production of embryos per female gametes, indicating higher costs of selfing and parthenogenesis than outcrossing on fertility. However, the increased fecundity compensated for the reduced fertility, leading to a stable overall reproductive output. Inbreeding also affected morphological traits of juvenile sporophytes, but not their heatwave tolerance. The male-female kinship effect was stronger in high-latitude populations, suggesting that females from low-latitude marginal populations might have evolved to mate with any male gamete to guarantee reproductive success.
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Affiliation(s)
- Carolina Camus
- Centro i~mar and CeBiB, Universidad de Los Lagos, Puerto Montt, Chile
| | - Maribel Solas
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Jaime Vargas
- Centro i~mar, Universidad de Los Lagos, Puerto Montt, Chile
| | | | | | - Lydia B Ladah
- Department of Biological Oceanography, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, México
| | | | - Sylvain Faugeron
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- UMI3614 Evolutionary Biology and Ecology of Algae, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Roscoff, France
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31
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Hartmann FE, Duhamel M, Carpentier F, Hood ME, Foulongne‐Oriol M, Silar P, Malagnac F, Grognet P, Giraud T. Recombination suppression and evolutionary strata around mating-type loci in fungi: documenting patterns and understanding evolutionary and mechanistic causes. THE NEW PHYTOLOGIST 2021; 229:2470-2491. [PMID: 33113229 PMCID: PMC7898863 DOI: 10.1111/nph.17039] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/03/2020] [Indexed: 05/08/2023]
Abstract
Genomic regions determining sexual compatibility often display recombination suppression, as occurs in sex chromosomes, plant self-incompatibility loci and fungal mating-type loci. Regions lacking recombination can extend beyond the genes determining sexes or mating types, by several successive steps of recombination suppression. Here we review the evidence for recombination suppression around mating-type loci in fungi, sometimes encompassing vast regions of the mating-type chromosomes. The suppression of recombination at mating-type loci in fungi has long been recognized and maintains the multiallelic combinations required for correct compatibility determination. We review more recent evidence for expansions of recombination suppression beyond mating-type genes in fungi ('evolutionary strata'), which have been little studied and may be more pervasive than commonly thought. We discuss testable hypotheses for the ultimate (evolutionary) and proximate (mechanistic) causes for such expansions of recombination suppression, including (1) antagonistic selection, (2) association of additional functions to mating-type, such as uniparental mitochondria inheritance, (3) accumulation in the margin of nonrecombining regions of various factors, including deleterious mutations or transposable elements resulting from relaxed selection, or neutral rearrangements resulting from genetic drift. The study of recombination suppression in fungi could thus contribute to our understanding of recombination suppression expansion across a broader range of organisms.
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Affiliation(s)
- Fanny E. Hartmann
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
| | - Marine Duhamel
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
- Ruhr‐Universität Bochum, Evolution of Plants and Fungi ‐ Gebäude ND 03/174Universitätsstraße150, 44801 BochumGermany
| | - Fantin Carpentier
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
| | - Michael E. Hood
- Biology Department, Science CentreAmherst CollegeAmherstMA01002USA
| | | | - Philippe Silar
- Lab Interdisciplinaire Energies DemainUniv Paris DiderotSorbonne Paris CiteParis 13F‐75205France
| | - Fabienne Malagnac
- Institute for Integrative Biology of the Cell (I2BC)Université Paris‐SaclayCEACNRSGif‐sur‐Yvette91198France
| | - Pierre Grognet
- Institute for Integrative Biology of the Cell (I2BC)Université Paris‐SaclayCEACNRSGif‐sur‐Yvette91198France
| | - Tatiana Giraud
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
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32
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Florez-Rueda AM, Scharmann M, Roth M, Städler T. Population Genomics of the "Arcanum" Species Group in Wild Tomatoes: Evidence for Separate Origins of Two Self-Compatible Lineages. FRONTIERS IN PLANT SCIENCE 2021; 12:624442. [PMID: 33815438 PMCID: PMC8018279 DOI: 10.3389/fpls.2021.624442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 02/24/2021] [Indexed: 05/07/2023]
Abstract
Given their diverse mating systems and recent divergence, wild tomatoes (Solanum section Lycopersicon) have become an attractive model system to study ecological divergence, the build-up of reproductive barriers, and the causes and consequences of the breakdown of self-incompatibility. Here we report on a lesser-studied group of species known as the "Arcanum" group, comprising the nominal species Solanum arcanum, Solanum chmielewskii, and Solanum neorickii. The latter two taxa are self-compatible but are thought to self-fertilize at different rates, given their distinct manifestations of the morphological "selfing syndrome." Based on experimental crossings and transcriptome sequencing of a total of 39 different genotypes from as many accessions representing each species' geographic range, we provide compelling evidence for deep genealogical divisions within S. arcanum; only the self-incompatible lineage known as "var. marañón" has close genealogical ties to the two self-compatible species. Moreover, there is evidence under multiple inference schemes for different geographic subsets of S. arcanum var. marañón being closest to S. chmielewskii and S. neorickii, respectively. To broadly characterize the population-genomic consequences of these recent mating-system transitions and their associated speciation events, we fit demographic models indicating strong reductions in effective population size, congruent with reduced nucleotide and S-locus diversity in the two independently derived self-compatible species.
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33
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Kerbs B, Crawford DJ, White G, Moura M, Borges Silva L, Schaefer H, Brown K, Mort ME, Kelly JK. How rapidly do self-compatible populations evolve selfing? Mating system estimation within recently evolved self-compatible populations of Azorean Tolpis succulenta (Asteraceae). Ecol Evol 2020; 10:13990-13999. [PMID: 33391697 PMCID: PMC7771160 DOI: 10.1002/ece3.6992] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 10/08/2020] [Accepted: 10/14/2020] [Indexed: 01/04/2023] Open
Abstract
Genome-wide genotyping and Bayesian inference method (BORICE) were employed to estimate outcrossing rates and paternity in two small plant populations of Tolpis succulenta (Asteraceae) on Graciosa island in the Azores. These two known extant populations of T. succulenta on Graciosa have recently evolved self-compatibility. Despite the expectation that selfing would occur at an appreciable rate (self-incompatible populations of the same species show low but nonzero selfing), high outcrossing was found in progeny arrays from maternal plants in both populations. This is inconsistent with an immediate transition to high selfing following the breakdown of a genetic incompatibility system. This finding is surprising given the small population sizes and the recent colonization of an island from self-incompatible colonists of T. succulenta from another island in the Azores, and a potential paucity of pollinators, all factors selecting for selfing through reproductive assurance. The self-compatible lineage(s) likely have high inbreeding depression (ID) that effectively halts the evolution of increased selfing, but this remains to be determined. Like their progeny, all maternal plants in both populations are fully outbred, which is consistent with but not proof of high ID. High multiple paternity was found in both populations, which may be due in part to the abundant pollinators observed during the flowering season.
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Affiliation(s)
- Benjamin Kerbs
- Department of Ecology & Evolutionary BiologyUniversity of KansasLawrenceKSUSA
| | - Daniel J. Crawford
- Department of Ecology & Evolutionary BiologyUniversity of KansasLawrenceKSUSA
- Biodiversity InstituteUniversity of KansasLawrenceKSUSA
| | - Griffin White
- Department of Ecology & Evolutionary BiologyUniversity of KansasLawrenceKSUSA
- ETH ZurichFunctional Genomics Center ZurichZurichSwitzerland
| | - Mónica Moura
- InBIO Laboratório Associado, Pólo dos AçoresFaculdade de Ciências TecnoclogiaCIBIO, Centro de Investigação em Biodiversidade e Recursos GenéticosUniversidade dos AçoresPonta DelgadaPortugal
| | - Lurdes Borges Silva
- InBIO Laboratório Associado, Pólo dos AçoresFaculdade de Ciências TecnoclogiaCIBIO, Centro de Investigação em Biodiversidade e Recursos GenéticosUniversidade dos AçoresPonta DelgadaPortugal
| | - Hanno Schaefer
- Department of Ecology and Ecosystem ManagementPlant Biodiversity ResearchTechnical University of MunichFreisingGermany
| | - Keely Brown
- Department of Ecology & Evolutionary BiologyUniversity of KansasLawrenceKSUSA
| | - Mark E. Mort
- Department of Ecology & Evolutionary BiologyUniversity of KansasLawrenceKSUSA
| | - John K. Kelly
- Department of Ecology & Evolutionary BiologyUniversity of KansasLawrenceKSUSA
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Jiménez-López FJ, Ortiz PL, Talavera M, Arista M. Reproductive Assurance Maintains Red-Flowered Plants of Lysimachia arvensis in Mediterranean Populations Despite Inbreeding Depression. FRONTIERS IN PLANT SCIENCE 2020; 11:563110. [PMID: 33324430 PMCID: PMC7725749 DOI: 10.3389/fpls.2020.563110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 10/28/2020] [Indexed: 06/12/2023]
Abstract
Flower color polymorphism, an infrequent but phylogenetically widespread condition in plants, is captivating because it can only be maintained under a few selective regimes but also because it can drive intra-morph assortative mating and promote speciation. Lysimachia arvensis is a polymorphic species with red or blue flowered morphs. In polymorphic populations, which are mostly Mediterranean, pollinators prefer blue-flowered plants to the red ones, and abiotic factors also favors blue-flowered plants. We hypothesize that the red morph is maintained in Mediterranean areas due to its selfing capacity. We assessed inbreeding depression in both color morphs in two Mediterranean populations and genetic diversity was studied via SSR microsatellites in 20 natural populations. Results showed that only 44-47% of selfed progeny of the red plants reached reproduction while about 72-91% of blue morph progeny did it. Between-morph genetic differentiation was high and the red morph had a lower genetic diversity and a higher inbreeding coefficient, mainly in the Mediterranean. Results suggest that selfing maintaining the red morph in Mediterranean areas despite its inbreeding depression. In addition, genetic differentiation between morphs suggests a low gene flow between them, suggesting reproductive isolation.
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Affiliation(s)
- Francisco J. Jiménez-López
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
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35
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Wessinger CA, Hileman LC. Parallelism in Flower Evolution and Development. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-124511] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Flower evolution is characterized by widespread repetition, with adaptations to pollinator environment evolving in parallel. Recent studies have expanded our understanding of the developmental basis of adaptive floral novelties—petal fusion, bilateral symmetry, heterostyly, and floral dimensions. In this article, we describe patterns of trait evolution and review developmental genetic mechanisms underlying floral novelties. We discuss the diversity of mechanisms for parallel adaptation, the evidence for constraints on these mechanisms, and how constraints help explain observed macroevolutionary patterns. We describe parallel evolution resulting from similarities at multiple hierarchical levels—genetic, developmental, morphological, functional—which indicate general principles in floral evolution, including the central role of hormone signaling. An emerging pattern is mutational bias that may contribute to rapid patterns of parallel evolution, especially if the derived trait can result from simple degenerative mutations. We argue that such mutational bias may be less likely to govern the evolution of novelties patterned by complex developmental pathways.
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Affiliation(s)
- Carolyn A. Wessinger
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Lena C. Hileman
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
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36
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Gibson MJS, Crawford DJ, Holder MT, Mort ME, Kerbs B, de Sequeira MM, Kelly JK. Genome-wide genotyping estimates mating system parameters and paternity in the island species Tolpis succulenta. AMERICAN JOURNAL OF BOTANY 2020; 107:1189-1197. [PMID: 32864742 DOI: 10.1002/ajb2.1515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 02/22/2020] [Indexed: 06/11/2023]
Abstract
PREMISE The mating system has profound consequences, not only for ecology and evolution, but also for the conservation of threatened or endangered species. Unfortunately, small populations are difficult to study owing to limits on sample size and genetic marker diversity. Here, we estimated mating system parameters in three small populations of an island plant using genomic genotyping. Although self-incompatible (SI) species are known to often set some self-seed, little is known about how "leaky SI" affects selfing rates in nature or the role that multiple paternity plays in small populations. METHODS We generalized the BORICE mating system program to determine the siring pattern within maternal families. We applied this algorithm to maternal families from three populations of Tolpis succulenta from Madeira Island and genotyped the progeny using RADseq. We applied BORICE to estimate each individual offspring as outcrossed or selfed, the paternity of each outcrossed offspring, and the level of inbreeding of each maternal plant. RESULTS Despite a functional self-incompatibility system, these data establish T. succulenta as a pseudo-self-compatible (PSC) species. Two of 75 offspring were strongly indicated as products of self-fertilization. Despite selfing, all adult maternal plants were fully outbred. There was high differentiation among and low variation within populations, consistent with a history of genetic isolation of these small populations. There were generally multiple sires per maternal family. Twenty-two percent of sib contrasts (between outcrossed offspring within maternal families) shared the same sire. CONCLUSIONS Genome-wide genotyping, combined with appropriate analytical methods, enables estimation of mating system and multiple paternity in small populations. These data address questions about the evolution of reproductive traits and the conservation of threatened populations.
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Affiliation(s)
- Matthew J S Gibson
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7534, USA
| | - Daniel J Crawford
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7534, USA
- Biodiversity Institute, University of Kansas, Lawrence, KS, 66045-7534, USA
| | - Mark T Holder
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7534, USA
- Biodiversity Institute, University of Kansas, Lawrence, KS, 66045-7534, USA
| | - Mark E Mort
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7534, USA
| | - Benjamin Kerbs
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7534, USA
| | - Miguel Menezes de Sequeira
- Madeira Botanical Group, Faculty of Life Sciences, University of Madeira, Campus Universitário da Penteada, 9020-105, Funchal, Portugal
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Pólo dos Açores, 9501-81, Ponta Delgada, Portugal
| | - John K Kelly
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS, 66045-7534, USA
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Felmy A, Weissert N, Travis J, Jokela J. Mate availability determines use of alternative reproductive phenotypes in hermaphrodites. Behav Ecol 2020. [DOI: 10.1093/beheco/araa046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
In many species, individuals can employ alternative reproductive phenotypes, with profound consequences for individual fitness and population dynamics. This is particularly relevant for self-compatible hermaphrodites, which have exceptionally many reproductive options. Here we investigated the occurrence of reproductive phenotypes in the simultaneously hermaphroditic freshwater snail Radix balthica under experimentally simulated conditions of low versus moderate population density. We captured all mating behavior on camera and measured individual female lifetime reproductive success. We found every possible reproductive phenotype: (1) both male and female (i.e., truly hermaphroditic) reproduction, (2) purely female and (3) purely male reproduction, (4) male reproduction combined with self-fertilization and (5) female mating activity, (6) pure self-fertilization without mating and (7–8) two types of reproductive failure. Variation in alternative reproductive phenotypes was explained by mate availability (10.8%) and individual condition, approximated by a snail’s mean daily growth rate (17.5%). Increased mate availability resulted in a lower diversity of reproductive phenotypes, in particular increasing the frequency of true hermaphrodites. However, it lowered phenotype-specific fecundities and hence reduced the population growth rate. Snails in better condition were more likely to reproduce as true hermaphrodites or pure females, whereas low-condition snails tended to suffer reproductive failure. Overall, we show substantial variation in alternative reproductive phenotypes in a hermaphrodite, which is possibly in part maintained by fluctuations in population density and thus mate availability, and by variation in individual condition. We also provide evidence of an almost 2-fold increase in clutch size that can be ascribed specifically to mating as a female.
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Affiliation(s)
- Anja Felmy
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf, Switzerland
- ETH Zurich, D-USYS, Institute of Integrative Biology, Universitätstrasse 16, Zurich, Switzerland
- Department of Zoology, University of Oxford, Oxford, UK
| | - Nora Weissert
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf, Switzerland
| | - Joseph Travis
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Jukka Jokela
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf, Switzerland
- ETH Zurich, D-USYS, Institute of Integrative Biology, Universitätstrasse 16, Zurich, Switzerland
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38
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Abu Awad D, Roze D. Epistasis, inbreeding depression, and the evolution of self-fertilization. Evolution 2020; 74:1301-1320. [PMID: 32386235 DOI: 10.1111/evo.13961] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 02/21/2020] [Indexed: 11/29/2022]
Abstract
Inbreeding depression resulting from partially recessive deleterious alleles is thought to be the main genetic factor preventing self-fertilizing mutants from spreading in outcrossing hermaphroditic populations. However, deleterious alleles may also generate an advantage to selfers in terms of more efficient purging, while the effects of epistasis among those alleles on inbreeding depression and mating system evolution remain little explored. In this article, we use a general model of selection to disentangle the effects of different forms of epistasis (additive-by-additive, additive-by-dominance, and dominance-by-dominance) on inbreeding depression and on the strength of selection for selfing. Models with fixed epistasis across loci, and models of stabilizing selection acting on quantitative traits (generating distributions of epistasis) are considered as special cases. Besides its effects on inbreeding depression, epistasis may increase the purging advantage associated with selfing (when it is negative on average), while the variance in epistasis favors selfing through the generation of linkage disequilibria that increase mean fitness. Approximations for the strengths of these effects are derived, and compared with individual-based simulation results.
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Affiliation(s)
- Diala Abu Awad
- Department of Population Genetics, Technical University of Munich, Munich, 80333, Germany
| | - Denis Roze
- Evolutionary Biology and Ecology of Algae, UMI 3614, CNRS, Roscoff, 29688, France.,Station Biologique de Roscoff, Sorbonne Université, Roscoff, 29688, France
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Woźniak NJ, Kappel C, Marona C, Altschmied L, Neuffer B, Sicard A. A Similar Genetic Architecture Underlies the Convergent Evolution of the Selfing Syndrome in Capsella. THE PLANT CELL 2020; 32:935-949. [PMID: 31964802 PMCID: PMC7145481 DOI: 10.1105/tpc.19.00551] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 11/19/2019] [Accepted: 01/13/2020] [Indexed: 05/11/2023]
Abstract
Whether, and to what extent, phenotypic evolution follows predictable genetic paths remains an important question in evolutionary biology. Convergent evolution of similar characters provides a unique opportunity to address this question. The transition to selfing and the associated changes in flower morphology are among the most prominent examples of repeated evolution in plants. In this study, we take advantage of the independent transitions to self-fertilization in the genus Capsella to compare the similarities between parallel modifications of floral traits and test for genetic and developmental constraints imposed on flower evolution in the context of the selfing syndrome. Capsella rubella and Capsella orientalis emerged independently but evolved almost identical flower characters. Not only is the evolutionary outcome identical but the same developmental strategies underlie the convergent reduction of flower size. This has been associated with convergent evolution of gene expression changes. The transcriptomic changes common to both selfing lineages are enriched in genes with low network connectivity and with organ-specific expression patterns. Comparative genetic mapping also suggests that, at least in the case of petal size evolution, these similarities have a similar genetic basis. Based on these results, we hypothesize that the limited availability of low-pleiotropy paths predetermines closely related species to similar evolutionary outcomes.
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Affiliation(s)
| | - Christian Kappel
- Institut für Biochemie und Biologie, Universität Potsdam, 14476 Potsdam-Golm, Germany
| | - Cindy Marona
- Institut für Biochemie und Biologie, Universität Potsdam, 14476 Potsdam-Golm, Germany
| | - Lothar Altschmied
- Leibniz Institute of Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany
| | - Barbara Neuffer
- Department of Botany, University of Osnabrück, 49076 Osnabrück, Germany
| | - Adrien Sicard
- Department of Plant Biology, Swedish University of Agricultural Sciences, Uppsala BioCenter and Linnean Centre for Plant Biology, 75007 Uppsala, Sweden
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40
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Huang Q, Wang W, Barrett SCH, Ren M. Plasticity in selective embryo abortion may limit the mating costs of geitonogamy in self-compatible plants: a hypothesis. AMERICAN JOURNAL OF BOTANY 2020; 107:390-393. [PMID: 32157677 DOI: 10.1002/ajb2.1448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Affiliation(s)
- Qiaoqiao Huang
- Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Weiqian Wang
- Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
- Center for Terrestrial Biodiversity of the South China Sea, College of Ecology and Environment, Hainan University, Haikou, 570228, China
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
| | - Mingxun Ren
- Center for Terrestrial Biodiversity of the South China Sea, College of Ecology and Environment, Hainan University, Haikou, 570228, China
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41
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Giannakara A, Ramm SA. Evidence for inter-population variation in waiting times in a self-fertilizing flatworm. INVERTEBR REPROD DEV 2020. [DOI: 10.1080/07924259.2020.1732485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
| | - Steven A. Ramm
- Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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42
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Brom T, Castric V, Billiard S. Breakdown of gametophytic self-incompatibility in subdivided populations. Evolution 2020; 74:270-282. [PMID: 31845323 DOI: 10.1111/evo.13897] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/04/2019] [Accepted: 11/11/2019] [Indexed: 01/11/2023]
Abstract
In many hermaphroditic flowering plants, self-fertilization is prevented by self-incompatibility (SI), often controlled by a single locus, the S-locus. In single isolated populations, the maintenance of SI depends chiefly on inbreeding depression and the number of SI alleles at the S-locus. In subdivided populations, however, population subdivision has complicated effects on both the number of SI alleles and the level of inbreeding depression, rendering the maintenance of SI difficult to predict. Here, we explore the conditions for the invasion of a self-compatible mutant in a structured population. We find that the maintenance of SI is strongly compromised when a population becomes subdivided. We show that this effect is mainly caused by the decrease in the local diversity of SI alleles rather than by a change in the dynamics of inbreeding depression. Strikingly, we also find that the diversity of SI alleles at the whole population level is a poor predictor of the maintenance of SI. We discuss the implications of our results for the interpretation of empirical data on the loss of SI in natural populations.
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Affiliation(s)
- Thomas Brom
- University Lille, UMR 8198 - Evo-Eco-Paleo, F-59000, Lille, France.,CNRS, UMR 8198, F-59000, Lille, France
| | - Vincent Castric
- University Lille, UMR 8198 - Evo-Eco-Paleo, F-59000, Lille, France.,CNRS, UMR 8198, F-59000, Lille, France
| | - Sylvain Billiard
- University Lille, UMR 8198 - Evo-Eco-Paleo, F-59000, Lille, France.,CNRS, UMR 8198, F-59000, Lille, France
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43
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Li Y, van Kleunen M, Stift M. Sibling competition does not magnify inbreeding depression in North American Arabidopsis lyrata. Heredity (Edinb) 2019; 123:723-732. [PMID: 31541202 PMCID: PMC6834581 DOI: 10.1038/s41437-019-0268-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 08/13/2019] [Accepted: 08/13/2019] [Indexed: 11/08/2022] Open
Abstract
About half of all angiosperms have some form of molecular self-incompatibility to promote outcrossing. If self-incompatibility breaks down, inbreeding depression (δ) is the main barrier to the evolution of self-fertilisation (selfing). If inbreeding depression is lower than 50% (δ < 0.5), the inherent transmission advantage of selfers should theoretically drive the evolution of selfing. However, this does not always happen in practice. For example, despite frequent breakdowns of self-incompatibility in North American Arabidopsis lyrata, selfing has only evolved in few populations. This is surprising given that previous inbreeding-depression estimates were well below the 0.5 threshold. Here, we test whether this could be due to underestimation of true inbreeding depression in competition-free environments. Specifically, we tested whether direct competition between crossed and selfed siblings magnified inbreeding-depression estimates in A. lyrata. We found that this was neither the case for belowground nor for aboveground biomass. For reproductive traits, there was hardly any significant inbreeding depression regardless of competition. Combined with previous findings that drought stress and inducing defence also did not magnify inbreeding depression, our results suggest that the relatively low estimates of inbreeding depression for biomass are indeed realistic estimates of the true inbreeding depression in North American A. lyrata.
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Affiliation(s)
- Yan Li
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, D-78457, Konstanz, Germany.
| | - Mark van Kleunen
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, D-78457, Konstanz, Germany
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, 318000, Taizhou, China
| | - Marc Stift
- Ecology, Department of Biology, University of Konstanz, Universitätsstrasse 10, D-78457, Konstanz, Germany
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44
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Cutter AD. Reproductive transitions in plants and animals: selfing syndrome, sexual selection and speciation. THE NEW PHYTOLOGIST 2019; 224:1080-1094. [PMID: 31336389 DOI: 10.1111/nph.16075] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 07/17/2019] [Indexed: 05/23/2023]
Abstract
The evolution of predominant self-fertilisation frequently coincides with the evolution of a collection of phenotypes that comprise the 'selfing syndrome', in both plants and animals. Genomic features also display a selfing syndrome. Selfing syndrome traits often involve changes to male and female reproductive characters that were subject to sexual selection and sexual conflict in the obligatorily outcrossing ancestor, including the gametic phase for both plants and animals. Rapid evolution of reproductive traits, due to both relaxed selection and directional selection under the new status of predominant selfing, lays the genetic groundwork for reproductive isolation. Consequently, shifts in sexual selection pressures coupled to transitions to selfing provide a powerful paradigm for investigating the speciation process. Plant and animal studies, however, emphasise distinct selective forces influencing reproductive-mode transitions: genetic transmission advantage to selfing or reproductive assurance outweighing the costs of inbreeding depression vs the costs of males and meiosis. Here, I synthesise links between sexual selection, evolution of selfing and speciation, with particular focus on identifying commonalities and differences between plant and animal systems and pointing to areas warranting further synergy.
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Affiliation(s)
- Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
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Fan YL, Barrett SCH, Yang JQ, Zhao JL, Xia YM, Li QJ. Water mediates fertilization in a terrestrial flowering plant. THE NEW PHYTOLOGIST 2019; 224:1133-1141. [PMID: 31032938 DOI: 10.1111/nph.15873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/17/2019] [Indexed: 06/09/2023]
Abstract
Water-mediated fertilization is ubiquitous in early land plants. This ancestral mode of fertilization has, however, generally been considered to have been lost during the evolutionary history of terrestrial flowering plants. We investigated reproductive mechanisms in the subtropical ginger Cautleya gracilis (Zingiberaceae), which has two pollen conditions - granular and filiform masses - depending on external conditions. We tested whether rain transformed granular pollen into filiform masses and whether this then promoted pollen-tube growth and fertilization of ovules. Using experimental manipulations in the field we investigated the contribution of water-mediated fertilization to seed production. Rain caused granular pollen to form filiform masses of germinating pollen tubes, which transported sperm to ovules, resulting in fertilization and seed set. Flowers exposed to rain produced significantly more seeds than those protected from the rain, which retained granular pollen. Insect pollination made only a limited contribution to seed set because rainy conditions limited pollinator service. Our results reveal a previously undescribed fertilization mechanism in flowering plants involving water-mediated fertilization stimulated by rain. Water-mediated fertilization is likely to be adaptive in the subtropical monsoon environments in which C. gracilis occurs by ensuring reproductive assurance when persistent rain prevents insect-mediated pollination.
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Affiliation(s)
- Yong-Li Fan
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China
- Kunming Survey & Design Institute of State Forestry and Grassland Administration, Kunming, Yunnan, 650216, China
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Ji-Qin Yang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
| | - Jian-Li Zhao
- Yunnan Key Laboratory of Plant Reproductive Adaption and Evolutionary Ecology, Yunnan University, Kunming, Yunnan, 650091, China
- Laboratory of Ecology and Evolutionary Biology, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan, 650216, China
| | - Yong-Mei Xia
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
| | - Qing-Jun Li
- Yunnan Key Laboratory of Plant Reproductive Adaption and Evolutionary Ecology, Yunnan University, Kunming, Yunnan, 650091, China
- Laboratory of Ecology and Evolutionary Biology, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan, 650216, China
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Zhong L, Barrett SCH, Wang XJ, Wu ZK, Sun HY, Li DZ, Wang H, Zhou W. Phylogenomic analysis reveals multiple evolutionary origins of selfing from outcrossing in a lineage of heterostylous plants. THE NEW PHYTOLOGIST 2019; 224:1290-1303. [PMID: 31077611 DOI: 10.1111/nph.15905] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 05/01/2019] [Indexed: 06/09/2023]
Abstract
Evolutionary transitions from outcrossing to selfing often occur in heterostylous plants. Selfing homostyles originate within distylous populations and frequently evolve to become reproductively isolated species. We investigated this process in 10 species of Primula section Obconicolisteri using phylogenomic approaches and inferred how often homostyly originated from distyly and its consequences for population genetic diversity and floral trait evolution. We estimated phylogenetic relationships and reconstructed character evolution using the whole plastome comprised of 76 protein-coding genes. To investigate mating patterns and genetic diversity we screened 15 microsatellite loci in 40 populations. We compared floral traits among distylous and homostylous populations to determine how phenotypically differentiated homostyles were from their distylous ancestors. Section Obconicolisteri was monophyletic and we estimated multiple independent transitions from distyly to homostyly. High selfing rates characterised homostylous populations and this was associated with reduced genetic diversity. Flower size and pollen production were reduced in homostylous populations, but pollen size was significantly larger in some homostyles than in distylous morphs. Repeated transitions to selfing in section Obconicolisteri are likely to have been fostered by the complex montane environments that species occupy. Unsatisfactory pollinator service is likely to have promoted reproductive assurance in homostyles leading to subsequent population divergence through isolation.
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Affiliation(s)
- Li Zhong
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, China
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
| | - Xin-Jia Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, China
| | - Zhi-Kun Wu
- Department of Pharmacy, Guiyang University of Traditional Chinese Medicine, Guiyang, Guizhou, 550002, China
| | - Hua-Ying Sun
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
| | - De-Zhu Li
- Plant Germplasm and Genomics Centre, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
| | - Hong Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
| | - Wei Zhou
- Plant Germplasm and Genomics Centre, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, Yunnan, 650201, China
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Koski MH, Galloway LF, Busch JW. Pollen limitation and autonomous selfing ability interact to shape variation in outcrossing rate across a species range. AMERICAN JOURNAL OF BOTANY 2019; 106:1240-1247. [PMID: 31415107 DOI: 10.1002/ajb2.1342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/28/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Hermaphroditic plants commonly reproduce through a mixture of selfing and outcrossing. The degree to which outcrossing rates reflect the availability of outcross pollen, genetic differentiation in the ability to autonomously self-fertilize, or both is often unclear. Despite the potential for autonomy and the pollination environment to jointly influence outcrossing, this interaction is rarely studied. METHODS We reviewed studies from the literature that tested whether the pollination environment or floral traits that cause autonomous selfing predict variation in outcrossing rate among populations. We also measured outcrossing rates in 23 populations of Campanula americana and examined associations with the pollination environment, autonomy, and their interaction. RESULTS Our review revealed that traits that facilitate selfing were often negatively associated with outcrossing rates whereas most aspects of the pollination environment poorly predicted outcrossing. Populations of C. americana varied from mixed mating to highly outcrossing, but variation was unrelated to population size, density, pollen limitation, or autonomous selfing ability. Outcrossing rate was significantly influenced by an interaction between autonomous selfing ability and pollen limitation. Across highly autonomous populations, elevated pollen limitation was associated with reduced outcrossing, while there was no relationship for less autonomous populations. CONCLUSIONS Both the ability to self autonomously and pollen limitation interact to shape outcrossing rates in C. americana. This work suggests that autonomy affords mating-system flexibility, though it is not ubiquitous in all populations across the species range. Interactions between traits influencing autonomy and pollen limitation are likely to explain variation in outcrossing rates among populations of flowering plants.
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Affiliation(s)
- Matthew H Koski
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia, 22904, USA
- Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, South Carolina, 29631, USA
| | - Laura F Galloway
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, Virginia, 22904, USA
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, Washington, 99164, USA
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Cutter AD, Morran LT, Phillips PC. Males, Outcrossing, and Sexual Selection in Caenorhabditis Nematodes. Genetics 2019; 213:27-57. [PMID: 31488593 PMCID: PMC6727802 DOI: 10.1534/genetics.119.300244] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 06/06/2019] [Indexed: 12/15/2022] Open
Abstract
Males of Caenorhabditis elegans provide a crucial practical tool in the laboratory, but, as the rarer and more finicky sex, have not enjoyed the same depth of research attention as hermaphrodites. Males, however, have attracted the attention of evolutionary biologists who are exploiting the C. elegans system to test longstanding hypotheses about sexual selection, sexual conflict, transitions in reproductive mode, and genome evolution, as well as to make new discoveries about Caenorhabditis organismal biology. Here, we review the evolutionary concepts and data informed by study of males of C. elegans and other Caenorhabditis We give special attention to the important role of sperm cells as a mediator of inter-male competition and male-female conflict that has led to drastic trait divergence across species, despite exceptional phenotypic conservation in many other morphological features. We discuss the evolutionary forces important in the origins of reproductive mode transitions from males being common (gonochorism: females and males) to rare (androdioecy: hermaphrodites and males) and the factors that modulate male frequency in extant androdioecious populations, including the potential influence of selective interference, host-pathogen coevolution, and mutation accumulation. Further, we summarize the consequences of males being common vs rare for adaptation and for trait divergence, trait degradation, and trait dimorphism between the sexes, as well as for molecular evolution of the genome, at both micro-evolutionary and macro-evolutionary timescales. We conclude that C. elegans male biology remains underexploited and that future studies leveraging its extensive experimental resources are poised to discover novel biology and to inform profound questions about animal function and evolution.
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Affiliation(s)
- Asher D Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Ontario M5S3B2, Canada
| | - Levi T Morran
- Department of Biology, Emory University, Atlanta, Georgia 30322, and
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403
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Ramírez N, Hokche O. Outbreeding and inbreeding strategies in herbaceous-shrubby communities in the Venezuelan Gran Sabana Plateau. AOB PLANTS 2019; 11:plz032. [PMID: 31308924 PMCID: PMC6621913 DOI: 10.1093/aobpla/plz032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 05/22/2019] [Indexed: 06/10/2023]
Abstract
Breeding system, sexual system, temporal variation in sex expression and herkogamy were evaluated in seven herbaceous-shrubby communities from the Gran Sabana Plateau, Venezuela. This analysis was conducted considering the life form, substrate type, succulence, carbon metabolism, nutritional relation, successional stage, pollination system specificity and endemism of plant species. Of the 348 plant species studied, 73.8 % were hermaphrodite, 16.9 % were monoecious and 9.2 % were dioecious. Plant sexual systems such as dichogamy and herkogamy were associated with life form, nutritional relations, carbon metabolism and pollination systems. Most species were adichogamous, followed by protandrous and protogynous. Protandry was high for perennial herbs, annual herbs and trees, and protogyny was most frequent in perennial herbs. Protandrous and protogynous species were frequently anemophilous. Herkogamy was higher than non-herkogamy. Herkogamy was higher for trees, shrubs and liana; higher in monophilous and lower in anemophilous species. Most of the hermaphrodites were herkogamous and adichogamous species. In contrast, monoecy were commonly perennial herb and dichogamous species and frequently associated with anemophily. Dioecious species were trees and shrubs and with polyphilous pollination. Dioecy was the most frequent sexual system for endemic species. Hermaphrodite species were similarly distributed across plant communities. Monoecy was slightly higher for savanna and fallow than the other communities, and dioecy was higher for shrublands and secondary bushland. Most plant species were non-agamospermous, non-spontaneous self-pollinated and xenogamous. Partially self-incompatible dominated, followed by self-incompatible, partially cross-incompatible and the lowest frequency corresponded to cross-incompatible species. All these results are discussed in the context of evolutionary and ecological trends.
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Affiliation(s)
- Nelson Ramírez
- Facultad de Ciencias, Instituto de Biología Experimental, Centro de Botánica Tropical, Universidad Central de Venezuela, Caracas 1041-A, Venezuela
| | - Omaira Hokche
- Herbario Nacional de Venezuela, Instituto Experimental Jardín Botánico Dr. Tobías Lasser, Universidad Central de Venezuela, Caracas, Venezuela
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Rifkin JL, Liao IT, Castillo AS, Rausher MD. Multiple aspects of the selfing syndrome of the morning glory Ipomoea lacunosa evolved in response to selection: A Qst-Fst comparison. Ecol Evol 2019; 9:7712-7725. [PMID: 31346434 PMCID: PMC6635925 DOI: 10.1002/ece3.5329] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 05/17/2019] [Accepted: 05/19/2019] [Indexed: 01/05/2023] Open
Abstract
The frequent transition from outcrossing to selfing in flowering plants is often accompanied by changes in multiple aspects of floral morphology, termed the "selfing syndrome." While the repeated evolution of these changes suggests a role for natural selection, genetic drift may also be responsible. To determine whether selection or drift shaped different aspects of the pollination syndrome and mating system in the highly selfing morning glory Ipomoea lacunosa, we performed multivariate and univariate Qst-Fst comparisons using a wide sample of populations of I. lacunosa and its mixed-mating sister species Ipomoea cordatotriloba. The two species differ in early growth, floral display, inflorescence traits, corolla size, nectar, and pollen number. Our analyses support a role for natural selection driving trait divergence, specifically in corolla size and nectar traits, but not in early growth, display size, inflorescence length, or pollen traits. We also find evidence of selection for reduced herkogamy in I. lacunosa, consistent with selection driving both the transition in mating system and the correlated floral changes. Our research demonstrates that while some aspects of the selfing syndrome evolved in response to selection, others likely evolved due to drift or correlated selection, and the balance between these forces may vary across selfing species.
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Affiliation(s)
| | - Irene T. Liao
- Department of BiologyDuke UniversityDurhamNorth Carolina
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