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He D, Liu XY, Zheng LT. Sex-specific scaling of leaf phosphorus vs. nitrogen under unequal reproductive requirements in Eurya japonica, a dioecious plant. AMERICAN JOURNAL OF BOTANY 2024; 111:e16311. [PMID: 38571288 DOI: 10.1002/ajb2.16311] [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: 10/11/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 04/05/2024]
Abstract
PREMISE Previous work searching for sexual dimorphism has largely relied on the comparison of trait mean vectors between sexes in dioecious plants. Whether trait scaling (i.e., the ratio of proportional changes in covarying traits) differs between sexes, along with its functional significance, remains unclear. METHODS We measured 10 vegetative traits pertaining to carbon, water, and nutrient economics across 337 individuals (157 males and 180 females) of the diocious species Eurya japonica during the fruiting season in eastern China. Piecewise structural equation modeling was employed to reveal the scaling relationships of multiple interacting traits, and multivariate analysis of (co)variance was conducted to test for intersexual differences. RESULTS There was no sexual dimorphism in terms of trait mean vectors across the 10 vegetative traits in E. japonica. Moreover, most relationships for covarying trait pairs (17 out of 19) exhibited common scaling slopes between sexes. However, the scaling slopes for leaf phosphorus (P) vs. nitrogen (N) differed between sexes, with 5.6- and 3.0-fold increases of P coinciding with a 10-fold increase of N in male and female plants, respectively. CONCLUSIONS The lower ratio of proportional changes in P vs. N for females likely reflects stronger P limitation for their vegetative growth, as they require greater P investments in fruiting. Therefore, P vs. N scaling can be a key avenue allowing for sex-specific strategic optimization under unequal reproductive requirements. This study uncovers a hidden aspect of secondary sex character in dioecious plants, and highlights the use of trait scaling to understand sex-defined economic strategies.
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Affiliation(s)
- Dong He
- College of Ecology and the Environment, Xinjiang University, Urumchi, PR China
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, PR China
| | - Xiang-Yu Liu
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, PR China
- Plant Ecology and Phytochemistry Group, Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Li-Ting Zheng
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, PR China
- Institute for Global Change Biology, School for Environment and Sustainability, University of Michigan, Ann Arbor, 48109, Michigan, USA
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Soininen JOS, Kytöviita M. Geranium sylvaticum increases pollination probability by sexually dimorphic flowers. Ecol Evol 2022; 12:e9670. [PMID: 36590340 PMCID: PMC9797467 DOI: 10.1002/ece3.9670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 12/10/2022] [Indexed: 12/29/2022] Open
Abstract
Sexual dimorphism is expressed as different morphologies between the sexes of a species. Dimorphism is pronounced in gynodioecious populations which consist of female and hermaphrodite individuals. The small size of female flowers in gynodioecious species is often explained by resource re-allocation to seed production instead of large flowers. However, pollinator attraction is critical to female fitness, and factors other than resource savings are needed to explain the small size of female flowers. We hypothesized that the floral size dimorphism in the perennial gynodioecious Geranium sylvaticum (L.) is adaptive in terms of pollination. To test this "pollination hypothesis," we video recorded the small female and large hermaphrodite G. sylvaticum flowers. We parameterized floral visitor behavior when visiting a flower and calculated pollination probabilities by a floral visitor as the probability of touching anther and stigma with the same body part. Pollination probability differed in terms of flower sex and pollinator species. Bumblebees had the highest pollination probability. The small female flowers were more likely to receive pollen via several pollinator groups than the large hermaphrodite flowers. The pollen display of hermaphrodites matched poorly with the stigma display of hermaphrodites, but well with that of females. Although the small size of female flowers is commonly explained by resource re-allocation, we show that sexual dimorphism in flower size may increase the main reproductive functions of the females and hermaphrodites. Dimorphism increases pollination probability in females and fathering probability of the hermaphrodites likely driving G. sylvaticum populations towards dioecy.
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Affiliation(s)
- Jaakko O. S. Soininen
- Department of Biological and Environmental Sciences, Faculty of Mathematics and ScienceUniversity of JyväskyläJyväskyläFinland
| | - Minna‐Maarit Kytöviita
- Department of Biological and Environmental Sciences, Faculty of Mathematics and ScienceUniversity of JyväskyläJyväskyläFinland
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Cauret CMS, Mortimer SME, Roberti MC, Ashman TL, Liston A. Chromosome-scale assembly with a phased sex-determining region resolves features of early Z and W chromosome differentiation in a wild octoploid strawberry. G3 (BETHESDA, MD.) 2022; 12:6603112. [PMID: 35666193 PMCID: PMC9339316 DOI: 10.1093/g3journal/jkac139] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/19/2022] [Indexed: 01/07/2023]
Abstract
When sex chromosomes stop recombining, they start to accumulate differences. The sex-limited chromosome (Y or W) especially is expected to degenerate via the loss of nucleotide sequence and the accumulation of repetitive sequences. However, how early signs of degeneration can be detected in a new sex chromosome is still unclear. The sex-determining region of the octoploid strawberries is young, small, and dynamic. Using PacBio HiFi reads, we obtained a chromosome-scale assembly of a female (ZW) Fragaria chiloensis plant carrying the youngest and largest of the known sex-determining region on the W in strawberries. We fully characterized the previously incomplete sex-determining region, confirming its gene content, genomic location, and evolutionary history. Resolution of gaps in the previous characterization of the sex-determining region added 10 kb of sequence including a noncanonical long terminal repeat-retrotransposon; whereas the Z sequence revealed a Harbinger transposable element adjoining the sex-determining region insertion site. Limited genetic differentiation of the sex chromosomes coupled with structural variation may indicate an early stage of W degeneration. The sex chromosomes have a similar percentage of repeats but differ in their repeat distribution. Differences in the pattern of repeats (transposable element polymorphism) apparently precede sex chromosome differentiation, thus potentially contributing to recombination cessation as opposed to being a consequence of it.
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Affiliation(s)
- Caroline M S Cauret
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Sebastian M E Mortimer
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Marcelina C Roberti
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
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Population Variability of Almond-Leaved Willow (Salix triandra L.) Based on the Leaf Morphometry: Isolation by Distance and Environment Explain Phenotypic Diversity. FORESTS 2022. [DOI: 10.3390/f13030420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Almond-leaved willow (Salix triandra L., Salicaceae) is a dioecious shrub, rarely a small tree that grows under various environmental conditions. We examined the population structure of 12 populations of almond-leaved willow using nine leaf morphological traits and specific leaf area. Populations were selected from a range of habitats, from continental to the sub-Mediterranean zone, to examine the influence of environmental conditions (climate and altitude) and geographic distance on leaf variability. Significant differences were confirmed among all populations for all traits, with significant correlations between geographic location of populations and morphological traits, and between environmental conditions and morphological traits. Large-leaved populations were found in continental and sub-Mediterranean climates, while small-leaved populations were found in higher elevations and smaller karstic rivers. In addition, populations from floodplains showed greater variability than populations from the karstic habitats, indicating a positive influence of lowland habitats and possible underlying differences in gene pool size. In conclusion, we found that environmental conditions and geographical distances in addition to genetic drift, are the main influences on the variability in almond-leaved willow, with the species showing a high level of plasticity and adaptation to local environmental conditions.
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Ryniewicz J, Roguz K, Mirski P, Brzosko E, Skłodowski M, Wróblewska A, Ostrowiecka B, Tałałaj I, Jermakowicz E, Zych M. Spatiotemporal Variations in Seed Set and Pollen Limitation in Populations of the Rare Generalist Species Polemonium caeruleum in Poland. FRONTIERS IN PLANT SCIENCE 2022; 12:755830. [PMID: 35046972 PMCID: PMC8761629 DOI: 10.3389/fpls.2021.755830] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/22/2021] [Indexed: 06/01/2023]
Abstract
A vast majority of angiosperms are pollinated by animals, and a decline in the number and diversity of insects often affects plant reproduction through pollen limitation. This phenomenon may be particularly severe in rare plant species, whose populations are shrinking. Here, we examined the variability in factors shaping reproductive success and pollen limitation in red-listed Polemonium caeruleum L. During a 5-year study in several populations of P. caeruleum (7-15, depending on year), we assessed the degree of pollen limitation based on differences in seed set between open-pollinated (control) and hand-pollinated flowers. We analysed the effects of flower visitors, population size, and meteorological data on plant reproductive success and pollen limitation. Our study showed that pollen limitation rarely affected P. caeruleum populations, and was present mainly in small populations. Pollen limitation index was negatively affected by the size of population, visitation frequency of all insects, and when considering the visitation frequency of individual groups, also by honeybee visits. Seed production in control treatment was positively influenced by the population size, average monthly precipitation in June and visits of hoverflies, while visits of honeybees, average monthly temperature in September, and average monthly precipitation in August influenced seed production negatively. As generalist plant P. caeruleum can be pollinated by diverse insect groups, however, in small populations their main visitors, the honeybees and bumblebees, may be less attracted, eventually leading to the disappearance of these populations. In pollination of P. caeruleum managed honeybees may play a dual role: while they are the most frequent and efficient flower visitors, their presence decreases seed set in open-pollinated flowers, which is most probably related to efficient pollen collection by these insects.
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Affiliation(s)
- Justyna Ryniewicz
- Botanic Garden, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Katarzyna Roguz
- Botanic Garden, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Paweł Mirski
- Faculty of Biology, University of Białystok, Białystok, Poland
| | - Emilia Brzosko
- Faculty of Biology, University of Białystok, Białystok, Poland
| | - Mateusz Skłodowski
- Botanic Garden, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Ada Wróblewska
- Faculty of Biology, University of Białystok, Białystok, Poland
| | | | - Izabela Tałałaj
- Faculty of Biology, University of Białystok, Białystok, Poland
| | | | - Marcin Zych
- Botanic Garden, Faculty of Biology, University of Warsaw, Warsaw, Poland
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6
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Wei N, Du Z, Liston A, Ashman TL. Genome duplication effects on functional traits and fitness are genetic context and species dependent: studies of synthetic polyploid Fragaria. AMERICAN JOURNAL OF BOTANY 2020; 107:262-272. [PMID: 31732972 DOI: 10.1002/ajb2.1377] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/09/2019] [Indexed: 05/21/2023]
Abstract
PREMISE Divergence in functional traits and adaptive responses to environmental change underlies the ecological advantage of polyploid plants in the wild. While established polyploids may benefit from combined outcomes of genome doubling, hybridization, and polyploidy-enabled adaptive evolution, whether genome doubling alone can drive ecological divergence or whether the outcome is genetically variable remains less clear. METHODS Using synthetic, colchicine-induced, autotetraploid (4x) plants derived from self-pollinated diploid (2x) seeds, and their colchicine-treated but unconverted diploid (2x.nc) full sibs from two diploid wild strawberry taxa (Fragaria vesca subsp. vesca and F. vesca subsp. bracteata), we examined the effects of genome doubling on functional traits, heat stress tolerance, and fitness components across taxa and maternal families (i.e., genetic families) within taxa. RESULTS Comparisons between 2x and 2x.nc plants indicated a negligible effect of colchicine treatment on functional traits. Genome doubling increased stomatal length and decreased stomatal density, specific leaf area, and leaf vein density, recapitulating patterns observed in wild polyploid Fragaria. Trichome density, heat stress tolerance, and relative growth rate were not significantly affected by genome doubling. Although clonal reproduction was reduced in response to genome doubling, this effect was strongly genetic-family dependent. CONCLUSIONS The results suggest that genome doubling during incipient speciation alone can generate ecological divergence and variation among genetic lineages. This response potentially allows for rapid short-term evolutionary adaptation and fuels genomic diversity and independent origins of polyploidy.
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Affiliation(s)
- Na Wei
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Zhaokui Du
- Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, and Institute of Ecology, Taizhou University, Taizhou, Zhejiang, 318000, PR China
| | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
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7
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Delph LF. Water availability drives population divergence and sex-specific responses in a dioecious plant. AMERICAN JOURNAL OF BOTANY 2019; 106:1346-1355. [PMID: 31538332 DOI: 10.1002/ajb2.1359] [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: 04/22/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Water availability is an important abiotic factor, resulting in differences between plant species growing in xeric and mesic habitats. Species with populations occurring in both habitat types allow examination of whether water availability has acted as a selective force at the intraspecific level. Investigating responses to water availability with a dioecious species allows determination of whether males and females, which often have different physiologies and life histories, respond differently. METHODS An experiment varying water availability was performed under an outdoor rain-out shelter using plants from two mesic and two xeric populations of the dioecious plant Silene latifolia. Early growth rate, flowering propensity, flower size, and specific leaf area were measured. At the end of the season, the plants were harvested, aboveground and root biomass were measured, and the total number of flowers and fruit produced were counted. RESULTS Compared to the two mesic populations, plants from the two xeric populations grew more slowly, were less likely to flower, took longer to flower, had thicker leaves, invested less in aboveground biomass and more in root biomass, produced fewer flowers and fruit, but were more likely to live. Many traits exhibited significant habitat type × treatment interactions. Compared to the xeric populations, males-but not females-from mesic populations had less root biomass and greatly reduced their flower production in response to low water availability. CONCLUSIONS Mesic and xeric populations responded in ways congruent with water availability being a selective force for among-population divergence, especially for males.
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Affiliation(s)
- Lynda F Delph
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
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8
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Korgiopoulou C, Bresta P, Nikolopoulos D, Karabourniotis G. Sex-specific structural and functional leaf traits and sun-shade acclimation in the dioecious tree Pistacia vera (Anacardiaceae). FUNCTIONAL PLANT BIOLOGY : FPB 2019; 46:649-659. [PMID: 31014446 DOI: 10.1071/fp18256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 02/26/2019] [Indexed: 06/09/2023]
Abstract
In dioecious species, sex-related adaptive strategies, influenced by natural and sexual selection, allow each sex to meet the specific demands of reproduction. Differences in ecophysiological traits between males and females may rely on innate differences in secondary sex traits such as structural and functional leaf traits. We tested structural sexual leaf dimorphism in Pistacia vera L. and the intersexual differences in sun-shade acclimation processes expected from the different adaptive strategies of males and females. Fifteen structural and functional leaf traits were compared in 50-year-old trees between females with low fruit load and males under sun and shade conditions. Despite the low additional energy investment in reproduction in females, remarkable sex effects in leaf structure and function were observed. Male trees had smaller leaves with significantly lower total conducting petiole area (TCA) and higher stomatal density, water use efficiency and concentration of phenolic compounds; females had larger leaves with greater thickness, leaf mass per area, TCA and maximum photosynthetic capacity per area (Amax,a). The higher Amax,a and stomatal conductance of female leaves were associated with their ~20-fold higher TCA compared with male trees. Females seem to invest more in high xylem efficiency and rates of C gain; males invest more in defence-protection. Sun-shade plastic responses were sex- and trait-specific, but the plasticity assessment indicated that both sexes have evolved an almost equal degree of phenotypic plasticity that allows them to perform optimally under varying environmental conditions. However, the trait-specific differences indicate that each sex displays a different strategy of optimisation.
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Affiliation(s)
- C Korgiopoulou
- Laboratory of Plant Physiology, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855 Botanikos, Athens, Greece
| | - P Bresta
- Laboratory of Plant Physiology, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855 Botanikos, Athens, Greece; and Corresponding author.
| | - D Nikolopoulos
- Laboratory of Plant Physiology, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855 Botanikos, Athens, Greece
| | - G Karabourniotis
- Laboratory of Plant Physiology, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855 Botanikos, Athens, Greece
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9
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Wei N, Cronn R, Liston A, Ashman T. Functional trait divergence and trait plasticity confer polyploid advantage in heterogeneous environments. THE NEW PHYTOLOGIST 2019; 221:2286-2297. [PMID: 30281801 PMCID: PMC6587808 DOI: 10.1111/nph.15508] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/24/2018] [Indexed: 05/09/2023]
Abstract
Polyploidy, or whole-genome duplication often with hybridization, is common in eukaryotes and is thought to drive ecological and evolutionary success, especially in plants. The mechanisms of polyploid success in ecologically relevant contexts, however, remain largely unknown. We conducted an extensive test of functional trait divergence and plasticity in conferring polyploid fitness advantage in heterogeneous environments, by growing clonal replicates of a worldwide genotype collection of six allopolyploid and five diploid wild strawberry (Fragaria) taxa in three climatically different common gardens. Among leaf functional traits, we detected divergence in trait means but not plasticities between polyploids and diploids, suggesting that increased genomic redundancy in polyploids does not necessarily translate into greater trait plasticity in response to environmental change. Across the heterogeneous garden environments, however, polyploids exhibited fitness advantage, which was conferred by both trait means and adaptive trait plasticities, supporting a 'jack-and-master' hypothesis for polyploids. Our findings elucidate essential ecological mechanisms underlying polyploid adaptation to heterogeneous environments, and provide an important insight into the prevalence and persistence of polyploid plants.
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Affiliation(s)
- Na Wei
- Department of Biological SciencesUniversity of PittsburghPittsburghPA15260USA
| | - Richard Cronn
- Pacific Northwest Research StationUnited States Department of Agriculture Forest ServiceCorvallisOR97331USA
| | - Aaron Liston
- Department of Botany and Plant PathologyOregon State UniversityCorvallisOR97331USA
| | - Tia‐Lynn Ashman
- Department of Biological SciencesUniversity of PittsburghPittsburghPA15260USA
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10
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Tennessen JA, Wei N, Straub SCK, Govindarajulu R, Liston A, Ashman TL. Repeated translocation of a gene cassette drives sex-chromosome turnover in strawberries. PLoS Biol 2018; 16:e2006062. [PMID: 30148831 PMCID: PMC6128632 DOI: 10.1371/journal.pbio.2006062] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 09/07/2018] [Accepted: 08/09/2018] [Indexed: 11/30/2022] Open
Abstract
Turnovers of sex-determining systems represent important diversifying forces across eukaryotes. Shifts in sex chromosomes—but conservation of the master sex-determining genes—characterize distantly related animal lineages. Yet in plants, in which separate sexes have evolved repeatedly and sex chromosomes are typically homomorphic, we do not know whether such translocations drive sex-chromosome turnovers within closely related taxonomic groups. This phenomenon can only be demonstrated by identifying sex-associated nucleotide sequences, still largely unknown in plants. The wild North American octoploid strawberries (Fragaria) exhibit separate sexes (dioecy) with homomorphic, female heterogametic (ZW) inheritance, yet sex maps to three different chromosomes in different taxa. To characterize these turnovers, we identified sequences unique to females and assembled their reads into contigs. For most octoploid Fragaria taxa, a short (13 kb) sequence was observed in all females and never in males, implicating it as the sex-determining region (SDR). This female-specific “SDR cassette” contains both a gene with a known role in fruit and pollen production and a novel retrogene absent on Z and autosomal chromosomes. Phylogenetic comparison of SDR cassettes revealed three clades and a history of repeated translocation. Remarkably, the translocations can be ordered temporally due to the capture of adjacent sequence with each successive move. The accumulation of the “souvenir” sequence—and the resultant expansion of the hemizygous SDR over time—could have been adaptive by locking genes into linkage with sex. Terminal inverted repeats at the insertion borders suggest a means of movement. To our knowledge, this is the first plant SDR shown to be translocated, and it suggests a new mechanism (“move-lock-grow”) for expansion and diversification of incipient sex chromosomes. Sex chromosomes frequently restructure themselves during organismal evolution, often becoming highly differentiated. This dynamic process is poorly understood for most taxa, especially during the early stages typical of many dioecious flowering plants. We show that in wild strawberries, a female-specific region of DNA is associated with sex and has repeatedly changed its genomic location, each time increasing the size of the hemizygous female-specific sequence on the W sex chromosome. This observation shows, for the first time to our knowledge, that plant sex regions can “jump” and suggests that this phenomenon may be adaptive by gathering and locking new genes into linkage with sex. This conserved and presumed causal sex-determining sequence, which varies in both genomic location and degree of differentiation, will facilitate future studies to understand how sex chromosomes first begin to differentiate.
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Affiliation(s)
- Jacob A. Tennessen
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Na Wei
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Shannon C. K. Straub
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Rajanikanth Govindarajulu
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Jácome-Flores ME, Delibes M, Wiegand T, Fedriani JM. Spatio-temporal arrangement of Chamaerops humilis inflorescences and occupancy patterns by its nursery pollinator, Derelomus chamaeropsis. ANNALS OF BOTANY 2018; 121:471-482. [PMID: 29300822 PMCID: PMC5838815 DOI: 10.1093/aob/mcx177] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 11/08/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND AND AIMS Nursery pollination is a highly specialized interaction in which pollinators breed inside plant reproductive structures. Pollinator occupancy of host plants often depends on plant location, flowering synchrony and sex. The nursery pollination system between the dioecious dwarf palm Chamaerops humilis (Arecaceae) and the host-specific palm flower weevil Derelomus chamaeropsis was investigated. For the first time, sex, flowering synchrony and spatial distribution of plants was related to the occupancy probability and the abundance of D. chamaeropsis larvae, important traits influencing both pollinator and plant fitness. METHODS During the flowering season, all inflorescences in anthesis were counted every 12 d and a flowering synchrony index was calculated taking into account all possible correlations with generalized linear mixed models. To analyse the spatial structure of plants, larva occupancy and abundance, different techniques of spatial point pattern analysis were used. KEY RESULTS In total, 5986 larvae in 1063 C. humilis inflorescences were recorded over three consecutive seasons. Male inflorescences showed a higher presence and abundance of weevil larvae than females, but interestingly approx. 30 % of the females held larvae. Also, larvae occurred mainly in highly synchronous plants with a low number of inflorescences, perhaps because those plants did not lead to a resource dilution effect. There was no evidence of spatial patterns in larva occupancy or abundance at any spatial scale, suggesting high dispersal ability of adult weevil. CONCLUSIONS The results in a nursery-pollinated dioecious palm demonstrate that plant sex, flowering display and flowering synchrony act as additive forces influencing the presence and abundance of the specialized pollinator larvae. Contradicting previous results, clear evidence that female dwarf palms also provide rewarding oviposition sites was found, and thus the plant 'pays' for the pollination services. The findings highlight that plant local aggregation is not always the main determinant of pollinator attraction, whereas flower traits and phenology could be critical in specialized plant-pollinator interactions.
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Affiliation(s)
- M E Jácome-Flores
- Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC), c/Américo Vespucio s/n, Seville, Spain
| | - Miguel Delibes
- Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC), c/Américo Vespucio s/n, Seville, Spain
| | - Thorsten Wiegand
- Department of Ecological Modelling, Helmholtz Centre for Environmental Research GmbH – UFZ, Permoserstrasse, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, Germany
| | - José M Fedriani
- Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC), c/Américo Vespucio s/n, Seville, Spain
- Department of Ecological Modelling, Helmholtz Centre for Environmental Research GmbH – UFZ, Permoserstrasse, Leipzig, Germany
- Technical University of Lisbon, Institute of Agronomy, Centre for Applied Ecology ‘Prof. Baeta Neves’/INBIO, Tapada da Ajuda, Lisboa, Portugal
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12
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Tennessen JA, Govindarajulu R, Liston A, Ashman T. Homomorphic ZW chromosomes in a wild strawberry show distinctive recombination heterogeneity but a small sex-determining region. THE NEW PHYTOLOGIST 2016; 211:1412-23. [PMID: 27102236 PMCID: PMC5074332 DOI: 10.1111/nph.13983] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/21/2016] [Indexed: 05/10/2023]
Abstract
Recombination in ancient, heteromorphic sex chromosomes is typically suppressed at the sex-determining region (SDR) and proportionally elevated in the pseudoautosomal region (PAR). However, little is known about recombination dynamics of young, homomorphic plant sex chromosomes. We examine male and female function in crosses and unrelated samples of the dioecious octoploid strawberry Fragaria chiloensis in order to map the small and recently evolved SDR controlling both traits and to examine recombination patterns on the incipient ZW chromosome. The SDR of this ZW system is located within a 280 kb window, in which the maternal recombination rate is lower than the paternal one. In contrast to the SDR, the maternal PAR recombination rate is much higher than the rates of the paternal PAR or autosomes, culminating in an elevated chromosome-wide rate. W-specific divergence is elevated within the SDR and a single polymorphism is observed in high species-wide linkage disequilibrium with sex. Selection for recombination suppression within the small SDR may be weak, but fluctuating sex ratios could favor elevated recombination in the PAR to remove deleterious mutations on the W. The recombination dynamics of this nascent sex chromosome with a modestly diverged SDR may be typical of other dioecious plants.
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Affiliation(s)
- Jacob A. Tennessen
- Department of Integrative BiologyOregon State UniversityCorvallisOR97331USA
| | | | - Aaron Liston
- Department of Botany and Plant PathologyOregon State UniversityCorvallisOR97331USA
| | - Tia‐Lynn Ashman
- Department of Biological SciencesUniversity of PittsburghPittsburghPA15260‐3929USA
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Sinclair JP, Kameyama Y, Shibata A, Kudo G. Male-biased hermaphrodites in a gynodioecious shrub, Daphne jezoensis. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:859-867. [PMID: 27090773 DOI: 10.1111/plb.12463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/13/2016] [Indexed: 06/05/2023]
Abstract
Gynodioecy, a state where female and hermaphrodite plants coexist in populations, has been widely proposed an intermediate stage in the evolutionary pathway from hermaphroditism to dioecy. In the gynodioecy-dioecy pathway, hermaphrodites may gain most of their fitness through male function once females invade populations. To test this prediction, comprehensive studies on sex ratio variation across populations and reproductive characteristics of hermaphrodite and female phenotypes are necessary. This study examined the variation in sex ratio, sex expression, flower and fruit production and sexual dimorphism of morphological traits in a gynodioecious shrub, Daphne jezoensis, over multiple populations and years. Population sex ratio (hermaphrodite:female) was close to 1:1 or slightly hermaphrodite-biased. Sex type of individual plants was largely fixed, but 15% of plants changed their sex during a 6-year census. Hermaphrodite plants produced larger flowers and invested 2.5 times more resources in flower production than female plants, but they exhibited remarkably low fruit set (proportion of flowers setting fruits). Female plants produced six times more fruits than hermaphrodite plants. Low fruiting ability of hermaphrodite plants was retained even when hand-pollination was performed. Fruit production of female plants was restricted by pollen limitation under natural conditions, irrespective of high potential fecundity, and this minimised the difference in resources allocated to reproduction between the sexes. Negative effects of previous flower and fruit production on current reproduction were not apparent in both sexes. This study suggests that gynodioecy in this species is functionally close to a dioecious mating system: smaller flower production with larger fruiting ability in female plants, and larger flower production with little fruiting ability in hermaphrodite plants.
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Affiliation(s)
- J P Sinclair
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Y Kameyama
- Faculty of Regional Environment Science, Tokyo University of Agriculture, Tokyo, Japan
| | - A Shibata
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - G Kudo
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
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Abstract
Dioecy (separate male and female individuals) ensures outcrossing and is more prevalent in animals than in plants. Although it is common in bryophytes and gymnosperms, only 5% of angiosperms are dioecious. In dioecious higher plants, flowers borne on male and female individuals are, respectively deficient in functional gynoecium and androecium. Dioecy is inherited via three sex chromosome systems: XX/XY, XX/X0 and WZ/ZZ, such that XX or WZ is female and XY, X0 or ZZ are males. The XX/XY system generates the rarer XX/X0 and WZ/ZZ systems. An autosome pair begets XY chromosomes. A recessive loss-of-androecium mutation (ana) creates X chromosome and a dominant gynoecium-suppressing (GYS) mutation creates Y chromosome. The ana/ANA and gys/GYS loci are in the sex-determining region (SDR) of the XY pair. Accumulation of inversions, deleterious mutations and repeat elements, especially transposons, in the SDR of Y suppresses recombination between X and Y in SDR, making Y labile and increasingly degenerate and heteromorphic from X. Continued recombination between X and Y in their pseudoautosomal region located at the ends of chromosomal arms allows survival of the degenerated Y and of the species. Dioecy is presumably a component of the evolutionary cycle for the origin of new species. Inbred hermaphrodite species assume dioecy. Later they suffer degenerate-Y-led population regression. Cross-hybridization between such extinguishing species and heterologous species, followed by genome duplication of segregants from hybrids, give rise to new species.
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Castilla AR, Alonso C, Herrera CM. Sex-specific phenotypic selection and geographic variation in gender divergence in a gynodioecious shrub. PLANT BIOLOGY (STUTTGART, GERMANY) 2015; 17:186-193. [PMID: 24841933 DOI: 10.1111/plb.12192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 03/09/2014] [Indexed: 06/03/2023]
Abstract
In sexually polymorphic plant species the extent of gender divergence in floral morphology and phenology may be influenced by gender-specific selection patterns imposed by pollinators, which may change geographically. Distribution margins are areas where changes in the pollinator fauna, and thus variation in gender divergence of floral traits, are expected. We tested for pollination-driven geographic variation in the gender divergence in floral and phenological traits in the gynodioecious shrub Daphne laureola, in core and marginal areas differing in the identity of the main pollinator. Pollinators selected for longer corolla tubes in hermaphrodite individuals only in core populations, which in turn recorded higher fruit set. Consistent with these phenotypic selection patterns, gender divergence in flower corolla length was higher in core populations. Moreover, pollinators selected towards delayed flowering on hermaphrodite individuals only in marginal populations, where the two sexes differed more in flowering time. Our results support that a shift in main pollinators is able to contribute to geographic variation in the gender divergence of sexually polymorphic plant species.
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Affiliation(s)
- A R Castilla
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain
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Liston A, Cronn R, Ashman TL. Fragaria: a genus with deep historical roots and ripe for evolutionary and ecological insights. AMERICAN JOURNAL OF BOTANY 2014; 101:1686-99. [PMID: 25326614 DOI: 10.3732/ajb.1400140] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The cultivated strawberry, Fragaria ×ananassa, is one of the youngest domesticated plants. Its 18th century origin via hybridization in Europe between the North American F. virginiana and the South American F. chiloensis was documented by the botanist Antoine Nicolas Duchesne. His 1766 "Natural History of Strawberries" is an extraordinary work that integrates fundamental discoveries on the biology, ecology, and phylogeny of Fragaria with applied information on cultivation and ethnobotanical uses, serving as an inspiration for current research in the genus. Fragaria species exhibit the full range of sexual systems in the gynodioecy pathway from hermaphroditism to dioecy (and back again), as well as variation in self-compatibility, and evidence of sex chromosomes with female heterogamety. The genus is also characterized by interspecific hybridization and polyploidy, with a natural range of ploidy levels from diploids to decaploids. This biological diversity, combined with the availability of genomic resources and the ease of growing and experimenting with the plants, makes Fragaria a very attractive system for ecological and evolutionary genomics. The goal of this review is to introduce Fragaria as a model genus and to provide a roadmap for future integrative research. These research directions will deepen our understanding of the ecological and evolutionary context that shaped the ancestors of the cultivated strawberry, not only providing information that can be applied to efforts to shape the future of this important fruit crop but also our understanding of key transitions in plant evolution.
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Affiliation(s)
- Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331 USA
| | - Richard Cronn
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, Oregon 97331 USA
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA
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Dalton RM, Koski MH, Ashman TL. Maternal sex effects and inbreeding depression under varied environmental conditions in gynodioecious Fragaria vesca subsp. bracteata. ANNALS OF BOTANY 2013; 112:613-21. [PMID: 23723257 PMCID: PMC3718212 DOI: 10.1093/aob/mct120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Gynodioecy (coexistence of females and hermaphrodites) is a sexual system that occurs in numerous flowering plant lineages. Thus, understanding the features that affect its maintenance has wide importance. Models predict that females must have a seed fitness advantage over hermaphrodites, and this may be achieved via seed quality or quantity. Females in a population of Fragaria vesca subsp. bracteata, a long-lived gynodioecious perennial, do not demonstrate a seed quantity advantage, so this study explored whether females produced better quality seed via maternal sex effects or avoidance of inbreeding depression (IBD). METHODS Families of selfed and outcrossed seed were created using hermaphrodite mothers and families of outcrossed seed were created using female mothers. The effects of these pollination treatments were assessed under benign conditions early in life and under varied conditions later in life. To test for an effect of maternal sex, fitness components and traits associated with acclimation to variable environments of progeny of outbred hermaphrodites and females were compared. To test for expression of IBD, fitness parameters between inbred and outbred progeny of hermaphrodites were compared. KEY RESULTS Offspring of females were more likely to germinate in benign conditions and survive in harsh resource environments than outbred progeny of hermaphrodites. IBD was low across most life stages, and both the effect of maternal sex on progeny quality and the expression of IBD depended on both maternal family and resource condition of the progeny. CONCLUSIONS The effect of maternal sex and IBD on progeny quality depended on resource conditions, maternal lineage and progeny life stage. In conjunction with known lack of differences in seed quantity, the quality advantages and IBD observed here are still unlikely to be sufficient for maintenance of gynodioecy under nuclear inheritance of male sterility.
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Govindarajulu R, Liston A, Ashman TL. Sex-determining chromosomes and sexual dimorphism: insights from genetic mapping of sex expression in a natural hybrid Fragaria × ananassa subsp. cuneifolia. Heredity (Edinb) 2013; 110:430-8. [PMID: 23169558 PMCID: PMC3630810 DOI: 10.1038/hdy.2012.96] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/23/2012] [Accepted: 08/27/2012] [Indexed: 01/23/2023] Open
Abstract
We studied the natural hybrid (Fragaria × ananassa subsp. cuneifolia) between two sexually dimorphic octoploid strawberry species (Fragaria virginiana and Fragaria chiloensis) to gain insight into the dynamics of sex chromosomes and the genesis of sexual dimorphism. Male sterility is dominant in both the parental species and thus will be inherited maternally, but the chromosome that houses the sex-determining region differs. Thus, we asked whether (1) the cytotypic composition of hybrid populations represents one or both maternal species, (2) the sex-determining chromosome of the hybrid reflects the location of male sterility within the maternal donor species and (3) crosses from the hybrid species show less sexual dimorphism than the parental species. We found that F. × ananassa subsp. cuneifolia populations consisted of both parental cytotypes but one predominated within each population. Genetic linkage mapping of two crosses showed dominance of male sterility similar to the parental species, however, the map location of male sterility reflected the maternal donor in one cross, but not the other. Moreover, female function mapped to a single region in the first cross, but to two regions in the second cross. Aside from components of female function (fruit set and seed set), other traits that have been found to be significantly sexually dimorphic in the pure species were either not dimorphic or were dimorphic in the opposite direction to the parental species. These results suggest that hybrids experience some disruption of dimorphism in secondary sexual traits, as well as novel location and number of quantitative trait locus (QTL) affecting sex function.
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Affiliation(s)
- R Govindarajulu
- Department of Biological Sciences, University
of Pittsburgh, Pittsburgh, PA, USA
| | - A Liston
- Department of Botany and Plant Pathology,
Oregon State University, Corvallis, OR,
USA
| | - T-L Ashman
- Department of Biological Sciences, University
of Pittsburgh, Pittsburgh, PA, USA
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Divergence in Defence against Herbivores between Males and Females of Dioecious Plant Species. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:897157. [PMID: 23320247 PMCID: PMC3540699 DOI: 10.1155/2012/897157] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/21/2012] [Accepted: 10/17/2012] [Indexed: 02/04/2023]
Abstract
Defensive traits may evolve differently between sexes in dioecious plant species. Our current understanding of this process hinges on a partial view of the evolution of resistance traits that may result in male-biased herbivory in dioecious populations. Here, we present a critical summary of the current state of the knowledge of herbivory in dioecious species and propose alternative evolutionary scenarios that have been neglected. These scenarios consider the potential evolutionary and functional determinants of sexual dimorphism in patterns of resource allocation to reproduction, growth, and defence. We review the evidence upon which two previous reviews of sex-biased herbivory have concluded that male-biased herbivory is a rule for dioecious species, and we caution readers about a series of shortcomings of many of these studies. Lastly, we propose a minimal standard protocol that should be followed in any studies that intend to elucidate the (co)evolution of interactions between dioecious plants and their herbivores.
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Spigler RB, Ashman TL. Gynodioecy to dioecy: are we there yet? ANNALS OF BOTANY 2012; 109:531-43. [PMID: 21807691 PMCID: PMC3278288 DOI: 10.1093/aob/mcr170] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 05/05/2011] [Indexed: 05/08/2023]
Abstract
BACKGROUND The 'gynodioecy-dioecy pathway' is considered to be one of the most important evolutionary routes from hermaphroditism to separate sexes (dioecy). Despite a large accumulation of evidence for female seed fertility advantages in gynodioecious species (females and hermaphrodites coexist) in support of the first step in the gynodioecy-dioecy pathway, we still have very little evidence for the second step, i.e. the transition from gynodioecy to dioecy. SCOPE We review the literature to evaluate whether basic predictions by theory are supported. To establish whether females' seed fertility advantage and frequencies are sufficient to favour the invasion of males, we review these for species along the gynodioecy-dioecy pathway published in the last 5 years. We then review the empirical evidence for predictions deriving from the second step, i.e. hermaphrodites' male fertility increases with female frequency, selection favours greater male fertility in hermaphrodites in gynodioecious species, and, where males and hermaphrodites coexist with females (subdioecy), males have greater male fertility than hermaphrodites. We review how genetic control and certain ecological features (pollen limitation, selfing, plasticity in sex expression and antagonists) influence the trajectory of a population along the gynodioecy-dioecy pathway. CONCLUSIONS Females tend to have greater seed fertility advantages over hermaphrodites where the two coexist, and this advantage is positively correlated with female frequency across species, as predicted by theory. A limited number of studies in subdioecious species have demonstrated that males have an advantage over hermaphrodites, as also predicted by theory. However, less evidence exists for phenotypic selection to increase male traits of hermaphrodites or for increasing male function of hermaphrodites in populations with high female frequency. A few key case studies underline the importance of examining multiple components of male fertility and the roles of pollen limitation, selfing and plasticity, when evaluating advantages. We conclude that we do not yet have a full understanding of the transition from gynodioecy to dioecy.
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Affiliation(s)
| | - Tia-Lynn Ashman
- Department of Biological Sciences, 4249 Fifth Ave., University of Pittsburgh, Pittsburgh, PA 15260-3929, USA
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Delph LF, Andicoechea J, Steven JC, Herlihy CR, Scarpino SV, Bell DL. Environment-dependent intralocus sexual conflict in a dioecious plant. THE NEW PHYTOLOGIST 2011; 192:542-552. [PMID: 21726233 DOI: 10.1111/j.1469-8137.2011.03811.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Intralocus sexual conflict is a form of conflict that does not involve direct interactions between males and females. It arises when selection on a shared trait with a common genetic basis differs between the sexes. Environmental factors, such as resource availability, may influence the expression and evolutionary outcome of such conflict. We quantified the genetic variance-covariance matrix, G, for both sexes of Silene latifolia for floral and leaf traits, as well as the between-sex matrix, B. We also quantified selection on the sexes via survival for 2 yr in four natural populations that varied in water availability. Environment-dependent intralocus sexual conflict exists for specific leaf area, a trait that is genetically correlated between the sexes. Males experienced significant negative selection, but only in populations with relatively limited water availability. Females experienced weakly positive or significant stabilizing selection on the same trait. Specific leaf area is genetically correlated with flower size and number, which are sexually dimorphic in this species. The extent of intralocus sexual conflict varied with the environment. Resolution of such conflict is likely to be confounded, given that specific leaf area is highly genetically integrated with other traits that are also divergent between the sexes.
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Affiliation(s)
- Lynda F Delph
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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Castilla AR, Alonso C, Herrera CM. Exploring local borders of distribution in the shrub Daphne laureola: Individual and populations traits. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2011. [DOI: 10.1016/j.actao.2011.02.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Spigler RB, Lewers KS, Ashman TL. GENETIC ARCHITECTURE OF SEXUAL DIMORPHISM IN A SUBDIOECIOUS PLANT WITH A PROTO-SEX CHROMOSOME. Evolution 2010; 65:1114-26. [DOI: 10.1111/j.1558-5646.2010.01189.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Zluvova J, Zak J, Janousek B, Vyskot B. Dioecious Silene latifolia plants show sexual dimorphism in the vegetative stage. BMC PLANT BIOLOGY 2010; 10:208. [PMID: 20854681 PMCID: PMC2956557 DOI: 10.1186/1471-2229-10-208] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 09/20/2010] [Indexed: 05/06/2023]
Abstract
BACKGROUND Prior to this study, no differences in gene expression between male and female dioecious plants in the vegetative state had been detected. Among dioecious plants displaying sexual dimorphism, Silene latifolia is one of the most studied species. Although many sexually dimorphic traits have been described in S. latifolia, all of them are quantitative, and they usually become apparent only after the initiation of flowering. RESULTS We present RT-PCR-based evidence that in S. latifolia, sexual dimorphism in gene expression is present long before the initiation of flowering. We describe three ESTs that show sex-specific (two male specific and one female specific) transcription at the rosette stage before the first flowering season. CONCLUSIONS To our knowledge, this study provides the first molecular evidence of early pre-flowering sexual dimorphism in angiosperms.
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Affiliation(s)
- Jitka Zluvova
- Department of Plant Developmental Genetics, Institute of Biophysics AS CR v. v. i., Kralovopolska 135, 612 65 Brno, Czech Republic
| | - Jiri Zak
- Department of Plant Developmental Genetics, Institute of Biophysics AS CR v. v. i., Kralovopolska 135, 612 65 Brno, Czech Republic
| | - Bohuslav Janousek
- Department of Plant Developmental Genetics, Institute of Biophysics AS CR v. v. i., Kralovopolska 135, 612 65 Brno, Czech Republic
| | - Boris Vyskot
- Department of Plant Developmental Genetics, Institute of Biophysics AS CR v. v. i., Kralovopolska 135, 612 65 Brno, Czech Republic
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Charlesworth D, Mank JE. The birds and the bees and the flowers and the trees: lessons from genetic mapping of sex determination in plants and animals. Genetics 2010; 186:9-31. [PMID: 20855574 PMCID: PMC2940314 DOI: 10.1534/genetics.110.117697] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The ability to identify genetic markers in nonmodel systems has allowed geneticists to construct linkage maps for a diversity of species, and the sex-determining locus is often among the first to be mapped. Sex determination is an important area of study in developmental and evolutionary biology, as well as ecology. Its importance for organisms might suggest that sex determination is highly conserved. However, genetic studies have shown that sex determination mechanisms, and the genes involved, are surprisingly labile. We review studies using genetic mapping and phylogenetic inferences, which can help reveal evolutionary pattern within this lability and potentially identify the changes that have occurred among different sex determination systems. We define some of the terminology, particularly where confusion arises in writing about such a diverse range of organisms, and highlight some major differences between plants and animals, and some important similarities. We stress the importance of studying taxa suitable for testing hypotheses, and the need for phylogenetic studies directed to taxa where the patterns of changes can be most reliably inferred, if the ultimate goal of testing hypotheses regarding the selective forces that have led to changes in such an essential trait is to become feasible.
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Affiliation(s)
- Deborah Charlesworth
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, United Kingdom.
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Caruso CM, Yakobowski SJ. Selection on floral and carbon uptake traits of Lobelia siphilitica is similar in females and hermaphrodites. J Evol Biol 2008; 21:1514-23. [PMID: 18811667 DOI: 10.1111/j.1420-9101.2008.01610.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sexual dimorphism is common in plants and animals. Although this dimorphism is often assumed to be adaptive, natural selection has rarely been measured on sexually dimorphic traits of plants. We measured phenotypic selection via seed set on two floral and four carbon uptake traits of female and hermaphrodite Lobelia siphilitica. Because females can reproduce only via seeds, which are costlier than pollen, we predicted that females with smaller flowers and enhanced carbon uptake would have higher fitness, resulting in either sex morph-specific directional selection or stabilizing selection for different optimal trait values in females and hermaphrodites. We found that directional selection on one carbon uptake trait differed between females and hermaphrodites. We did not detect significant stabilizing selection on traits of either sex morph. Our results provide little support for the hypothesis that sexual dimorphism in gynodioecious plants evolved in response to sex morph-specific selection.
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Affiliation(s)
- C M Caruso
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.
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28
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Spigler RB, Lewers KS, Main DS, Ashman TL. Genetic mapping of sex determination in a wild strawberry, Fragaria virginiana, reveals earliest form of sex chromosome. Heredity (Edinb) 2008; 101:507-17. [PMID: 18797475 DOI: 10.1038/hdy.2008.100] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The evolution of separate sexes (dioecy) from hermaphroditism is one of the major evolutionary transitions in plants, and this transition can be accompanied by the development of sex chromosomes. Studies in species with intermediate sexual systems are providing unprecedented insight into the initial stages of sex chromosome evolution. Here, we describe the genetic mechanism of sex determination in the octoploid, subdioecious wild strawberry, Fragaria virginiana Mill., based on a whole-genome simple sequence repeat (SSR)-based genetic map and on mapping sex determination as two qualitative traits, male and female function. The resultant total map length is 2373 cM and includes 212 markers on 42 linkage groups (mean marker spacing: 14 cM). We estimated that approximately 70 and 90% of the total F. virginiana genetic map resides within 10 and 20 cM of a marker on this map, respectively. Both sex expression traits mapped to the same linkage group, separated by approximately 6 cM, along with two SSR markers. Together, our phenotypic and genetic mapping results support a model of gender determination in subdioecious F. virginiana with at least two linked loci (or gene regions) with major effects. Reconstruction of parental genotypes at these loci reveals that both female and hermaphrodite heterogamety exist in this species. Evidence of recombination between the sex-determining loci, an important hallmark of incipient sex chromosomes, suggest that F. virginiana is an example of the youngest sex chromosome in plants and thus a novel model system for the study of sex chromosome evolution.
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Affiliation(s)
- R B Spigler
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260-3929, USA
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Alonso C, Mutikainen P, Herrera CM. Ecological context of breeding system variation: sex, size and pollination in a (predominantly) gynodioecious shrub. ANNALS OF BOTANY 2007; 100:1547-56. [PMID: 17933844 PMCID: PMC2759233 DOI: 10.1093/aob/mcm254] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 08/03/2007] [Accepted: 08/29/2007] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Species that exhibit among-population variation in breeding system are particularly suitable to study the importance of the ecological context for the stability and evolution of gender polymorphism. Geographical variation in breeding system and sex ratio of Daphne laureola (Thymelaeaceae) was examined and their association with environmental conditions, plant and floral display sizes, and pollination environment in a broad geographic scale was analysed. METHODS The proportion of female and hermaphrodite individuals in 38 populations within the Iberian Peninsula was scored. Average local temperature and precipitation from these sites were obtained from interpolation models based on 30 years of data. Pollination success was estimated as stigmatic pollen loads, pollen tubes per ovule and the proportion of unfertilized flowers per individual in a sub-set of hermaphroditic and gynodioecious populations. KEY RESULTS Daphne laureola is predominantly gynodioecious, but hermaphroditic populations were found in northeastern and southwestern regions, characterized by higher temperatures and lower annual precipitation. In the gynodioecious populations, female plants were larger and bore more flowers than hermaphrodites. However, due to their lower pollination success, females did not consistently produce more seeds than hermaphrodites, which tends to negate a seed production advantage in D. laureola females. In the northeastern hermaphroditic populations, plants were smaller and produced 9-13 times fewer flowers than in the other Iberian regions, and thus presumably had a lower level of geitonogamous self-fertilization. However, in a few southern populations hermaphroditism was not associated with small plant size and low flower production. CONCLUSIONS The findings highlight that different mechanisms, including abiotic conditions and pollinator service, may account for breeding system variation within a species' distribution range and also suggest that geitonogamy may affect plant breeding system evolution.
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Affiliation(s)
- Conchita Alonso
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Avenida de Maria Luisa s/n, E-41013 Sevilla, Spain.
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Weller SG, Sakai AK, Culley TM, Campbell DR, Ngo P, Dunbar-Wallis AK. Sexually dimorphic inflorescence traits in a wind-pollinated species: heritabilities and genetic correlations in Schiedea adamantis (Caryophyllaceae). AMERICAN JOURNAL OF BOTANY 2007; 94:1716-1725. [PMID: 21636368 DOI: 10.3732/ajb.94.10.1716] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Sexual dimorphism may be especially pronounced in wind-pollinated species because they lack the constraints of biotically pollinated species that must present their pollen and stigmas in similar positions to ensure pollen transfer. Lacking these constraints, the sexes of wind-pollinated species may diverge in response to the different demands of pollen dispersal and receipt, depending on the magnitude of genetic correlations preventing divergence between sexes. Patterns of sexual dimorphism and genetic variation were investigated for inflorescence traits in Schiedea adamantis (Caryophyllaceae), a species well adapted to wind-pollination, and compared to S. salicaria, a species with fewer adaptations to wind pollination. For S. adamantis, dimorphism was pronounced for inflorescence condensation and its components, including lateral flower number and pedicel length. Within sexes, genetic correlations between traits may constrain the relative shape of the inflorescence. Correlations detected across sexes may retard the evolution of sexual dimorphism in inflorescence structure, including features favoring enhanced dispersal and receipt of pollen. Despite genetic correlations across sexes, common principal components analysis showed that genetic variance-covariance matrices (G matrices) differed significantly between the sexes, in part because of greater genetic variation for flower number in hermaphrodites than in females. G matrices also differed between closely related S. adamantis and S. salicaria, indicating the potential for divergent evolution of inflorescence structure despite general similarities in morphology and pollination biology.
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Affiliation(s)
- Stephen G Weller
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697 USA
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Fedorka KM, Winterhalter WE, Mousseau TA. The evolutionary genetics of sexual size dimorphism in the cricket Allonemobius socius. Heredity (Edinb) 2007; 99:218-23. [PMID: 17473861 DOI: 10.1038/sj.hdy.6800985] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In recent years, investigations into the evolution of sexual size dimorphism have moved from a simple single trait, single sex perspective, to the more robust view of multivariate selection acting on both males and females. However, more accurate predictions regarding selection response may be possible if some knowledge of the underlying sex-specific genetic architecture exists. In the striped ground cricket, Allonemobius socius, females are the larger sex. Furthermore, body size appears to be closely associated with fitness in both males and females. Here, we investigate the role that genetic architecture may play in affecting this pattern. Employing a quantitative genetic approach, we estimated the sex-specific selection gradients and the (co)variance matrix for body size and wing morphology (that is, either a long-winged flight-capable phenotype or a short-winged flightless phenotype) to predict phenotypic change in the next generation. We found that the sexes differed significantly in their selection gradients as well as several of their genetic parameters. Our predictions of next-generation change indicated that the within-sex genetic correlations, as well as the between-sex genetic correlations, should play a significant role in sexually dimorphic evolution in this system. Specifically, the female size response was increased by approximately 178% when the between-sex genetic correlations were considered. Thus, our predictions reinforce the notion that genetic architecture can produce counterintuitive responses to selection, and suggest that even a complete knowledge of the selection pressures acting on a trait may misrepresent the trajectory of trait evolution.
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Affiliation(s)
- K M Fedorka
- Department of Biology, University of Central Florida, Orlando, FL 32816, USA
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Nunney L. Pupal period and adult size in Drosophila melanogaster: a cautionary tale of contrasting correlations between two sexually dimorphic traits. J Evol Biol 2007; 20:141-51. [PMID: 17210007 DOI: 10.1111/j.1420-9101.2006.01214.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sexual dimorphism (SD) is widespread, reflecting a resolution of genetic conflicts arising from sex-specific differences in selection. However, genetic correlations among traits may constrain the evolution of SD. Drosophila melanogaster exhibits SD for pupal period (males longer) and adult weight (females heavier). This negative inter-sex covariance between the traits contrasts with a significant intra-sex positive genetic correlation (r(g) = 0.95) estimated using lines selected for fast larval development. Path analysis indicated that within sexes the selection regime indirectly reduced adult weight which in turn reduced pupal period. A hypothesis is proposed for the evolution of SD whereby the trait 'pupal period' is divided into 'intrinsic' (correlated with body size) and 'ecological' (uncorrelated with body size) components, and (the larger) females eclose earlier than males size via a shortening of the ecological component, thus achieving the advantage of provisioning eggs prior to sexual maturity. This hypothesis avoids invoking successful 'incompatible antagonistic selection'.
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Affiliation(s)
- L Nunney
- Department of Biology, University of California, Riverside, CA 92521, USA.
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Ashman TL, Majetic CJ. Genetic constraints on floral evolution: a review and evaluation of patterns. Heredity (Edinb) 2006; 96:343-52. [PMID: 16598191 DOI: 10.1038/sj.hdy.6800815] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The characteristics of flowers influence most aspects of angiosperm reproduction, including the agents of pollination and patterns of mating. Thus, a clear view of the forces that mediate floral phenotypic evolution is central to understanding angiosperm diversity. Here, we inform on the capacity for floral phenotype to respond to selection by reviewing published data on heritabilities and genetic correlations for several classes of floral traits (primary sexual, attraction, mating system) in hermaphroditic plants. We find significant heritability for all floral traits but also variation among them, as well as a tendency for heritability to vary with mating system, but not life history. We additionally test predictions stemming from life history theory (eg, negative covariation between male-female traits and flower size-flower number), and ideas concerning the extent and pattern of genetic integration between flowers and leaves, and between the sexes of dioecious and gynodioecious species. We find mixed evidence for life history tradeoffs. We find strong support for floral integration and its relation with floral morphology (actinomorphy vs zygomorphy) and for a decoupling of floral and vegetative traits, but no evidence that modular integration varies with floral morphology. Lastly, we find mixed evidence for a relationship between the level of sexual dimorphism in attraction traits and the between-sex correlation in gender dimorphic plants.
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Affiliation(s)
- T-L Ashman
- 1Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Ave and Ruskin, Pittsburgh, PA 15260, USA.
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