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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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Tel-Zur N. Preventing self-fertilization: Insights from Ziziphus species. FRONTIERS IN PLANT SCIENCE 2023; 14:1226502. [PMID: 37662155 PMCID: PMC10471802 DOI: 10.3389/fpls.2023.1226502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Accepted: 08/02/2023] [Indexed: 09/05/2023]
Abstract
The fitness of self-progeny individuals is inferior to that of their outcrossed counterparts, resulting in a reduction in a plant population's ability to survive and reproduce. To prevent self-fertilization, angiosperms with hermaphrodite flowers may exploit a variety of mechanisms, including synchronous dichogamy and self-incompatibility. Synchronous dichogamy involves two flowering morphs, with strict within-morph synchronization, thereby preventing not only autogamy and geitonogamy but also intra-morph mating. Self-fertilization is also prevented by self-incompatibility, a genetic mechanism that allows the identification and rejection of "self" pollen, thereby preventing both autogamy and geitonogamy. Here, I seek to provide a perspective of flowering in Ziziphus species exhibiting both synchronous (i.e., "Early" morph flowers open in the morning and "Late" morph flowers open in the afternoon) protandrous dichogamy (i.e., pollen dispersal before the stigma becomes receptive) and self-incompatibility.
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Busch JW, Bodbyl‐Roels S, Tusuubira S, Kelly JK. Pollinator loss causes rapid adaptive evolution of selfing and dramatically reduces genome-wide genetic variability. Evolution 2022; 76:2130-2144. [PMID: 35852008 PMCID: PMC9543508 DOI: 10.1111/evo.14572] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/23/2022] [Accepted: 04/20/2022] [Indexed: 01/22/2023]
Abstract
Although selfing populations harbor little genetic variation limiting evolutionary potential, the causes are unclear. We experimentally evolved large, replicate populations of Mimulus guttatus for nine generations in greenhouses with or without pollinating bees and studied DNA polymorphism in descendants. Populations without bees adapted to produce more selfed seed yet exhibited striking reductions in DNA polymorphism despite large population sizes. Importantly, the genome-wide pattern of variation cannot be explained by a simple reduction in effective population size, but instead reflects the complicated interaction between selection, linkage, and inbreeding. Simulations demonstrate that the spread of favored alleles at few loci depresses neutral variation genome wide in large populations containing fully selfing lineages. It also generates greater heterogeneity among chromosomes than expected with neutral evolution in small populations. Genome-wide deviations from neutrality were documented in populations with bees, suggesting widespread influences of background selection. After applying outlier tests to detect loci under selection, two genome regions were found in populations with bees, yet no adaptive loci were otherwise mapped. Large amounts of stochastic change in selfing populations compromise evolutionary potential and undermine outlier tests for selection. This occurs because genetic draft in highly selfing populations makes even the largest changes in allele frequency unremarkable.
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Affiliation(s)
- Jeremiah W. Busch
- School of Biological SciencesWashington State UniversityPullmanWashington99164
| | - Sarah Bodbyl‐Roels
- Trefny Innovative Instruction CenterColorado School of MinesGoldenColorado80401
| | - Sharif Tusuubira
- Department of Ecology and Evolutionary BiologyUniversity of KansasLawrenceKansas66045
| | - John K. Kelly
- Department of Ecology and Evolutionary BiologyUniversity of KansasLawrenceKansas66045
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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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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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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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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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8
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Koski MH, Layman NC, Prior CJ, Busch JW, Galloway LF. Selfing ability and drift load evolve with range expansion. Evol Lett 2019; 3:500-512. [PMID: 31636942 PMCID: PMC6791181 DOI: 10.1002/evl3.136] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 08/09/2019] [Accepted: 08/11/2019] [Indexed: 12/16/2022] Open
Abstract
Colonization at expanding range edges often involves few founders, reducing effective population size. This process can promote the evolution of self-fertilization, but implicating historical processes as drivers of trait evolution is often difficult and requires an explicit model of biogeographic history. In plants, contemporary limits to outcrossing are often invoked as evolutionary drivers of self-fertilization, but historical expansions may shape mating system diversity, with leading-edge populations evolving elevated selfing ability. In a widespread plant, Campanula americana, we identified a glacial refugium in the southern Appalachian Mountains from spatial patterns of genetic drift among 24 populations. Populations farther from this refugium have smaller effective sizes and fewer rare alleles. They also displayed elevated heterosis in among-population crosses, reflecting the accumulation of deleterious mutations during range expansion. Although populations with elevated heterosis had reduced segregating mutation load, the magnitude of inbreeding depression lacked geographic pattern. The ability to self-fertilize was strongly positively correlated with the distance from the refugium and mutation accumulation-a pattern that contrasts sharply with contemporary mate and pollinator limitation. In this and other species, diversity in sexual systems may reflect the legacy of evolution in small, colonizing populations, with little or no relation to the ecology of modern populations.
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Affiliation(s)
- Matthew H Koski
- Department of Biology University of Virginia Charlottesville Virginia 22902.,Current Address: Department of Biological Sciences Clemson University Clemson SC 29631
| | - Nathan C Layman
- School of Biological Sciences Washington State University Pullman Washington 99164
| | - Carly J Prior
- School of Biological Sciences Washington State University Pullman Washington 99164
| | - Jeremiah W Busch
- School of Biological Sciences Washington State University Pullman Washington 99164
| | - Laura F Galloway
- Department of Biology University of Virginia Charlottesville Virginia 22902
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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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10
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Voillemot M, Encinas-Viso F, Pannell JR. Rapid loss of self-incompatibility in experimental populations of the perennial outcrossing plant Linaria cavanillesii. Evolution 2019; 73:913-926. [PMID: 30874301 DOI: 10.1111/evo.13721] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 02/18/2019] [Indexed: 11/30/2022]
Abstract
Transitions from self-incompatibility to self-compatibility in angiosperms may be frequently driven by selection for reproductive assurance when mates or pollinators are rare, and are often succeeded by loss of inbreeding depression by purging. Here, we use experimental evolution to investigate the spread of self-compatibility from one such population of the perennial plant Linaria cavanillesii into self-incompatible (SI) populations that still have high inbreeding depression. We introduced self-compatible (SC) individuals at different frequencies into replicate experimental populations of L. cavanillesii that varied in access to pollinators. Our experiment revealed a rapid shift to self-compatibility in all replicates, driven by both greater seed set and greater outcross siring success of SC individuals. We discuss our results in the light of computer simulations that confirm the tendency of self-compatibility to spread into SI populations under the observed conditions. Our study illustrates the ease with which self-compatibility can spread among populations, a requisite for species-wide transitions from self-incompatibility to self-compatibility.
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Affiliation(s)
- Marie Voillemot
- Department of Ecology and Evolution, Biophore/Sorge, University of Lausanne, 1015, Lausanne, Switzerland
| | - Francisco Encinas-Viso
- Centre for Australian National Biodiversity Research, CSIRO, Canberra, ACT 2601, Australia
| | - John R Pannell
- Department of Ecology and Evolution, Biophore/Sorge, University of Lausanne, 1015, Lausanne, Switzerland
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Roda F, Hopkins R. Correlated evolution of self and interspecific incompatibility across the range of a Texas wildflower. THE NEW PHYTOLOGIST 2019; 221:553-564. [PMID: 29992588 DOI: 10.1111/nph.15340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 06/10/2018] [Indexed: 06/08/2023]
Abstract
Selection to prevent interspecific mating can cause an increase or a decrease in self-pollination in sympatric populations. Characterizing the geographical variation in self and interspecific incompatibilities within a species can reveal if and how the evolution of self and interspecific mate choice are linked. We used controlled pollinations to characterize the variation in self and interspecific incompatibility across 29 populations of Phlox drummondii. We evaluated seed set from these pollinations and described the developmental timing of variation in pollen-pistil compatibility. There is extensive quantitative variation in self-incompatibility and interspecific-incompatibility with its close congener P. cuspidata. Phlox drummondii populations that co-occur and hybridize with P. cuspidata have significantly higher interspecific incompatibility and self-incompatibility than geographically isolated P. drummondii populations. The strength of self and interspecific incompatibility is significantly correlated among individuals and the strength of both incompatibilities is explained by the success of pollen adhesion to the stigma. The correlated strength of self and interspecific incompatibility across the range of P. drummondii and the concurrent developmental timing of the pollen-pistil interaction, suggests these incompatibilities have an overlapping molecular mechanism. The geographical distribution of variation in incompatibilities indicates that this mechanistic link between incompatibilities may affect the evolution of mate choice in plants.
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Affiliation(s)
- Federico Roda
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, 1300 Centre St, Boston, MA, 02131, USA
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, 1300 Centre St, Boston, MA, 02131, USA
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12
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Layman NC, Busch JW. Bottlenecks and inbreeding depression in autotetraploids. Evolution 2018; 72:2025-2037. [PMID: 30136722 DOI: 10.1111/evo.13587] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/14/2018] [Indexed: 12/30/2022]
Abstract
Inbreeding depression is dependent on the ploidy of populations and can inhibit the evolution of selfing. While polyploids should generally harbor less inbreeding depression than diploids at equilibrium, it has been unclear whether this pattern holds in non-equilibrium conditions following bottlenecks. We use stochastic individual-based simulations to determine the effects of population bottlenecks on inbreeding depression in diploids and autotetraploids, in addition to cases where neo-autotetraploids form from the union of unreduced gametes. With a ploidy-independent dominance function based on enzyme kinetics, inbreeding depression is generally lower in autotetraploids for fully and partially recessive mutations. Due to the sampling of more chromosomes during reproduction, bottlenecks generally reduce inbreeding depression to a lesser extent in autotetraploids. All else being equal, population bottlenecks may have ploidy-dependent effects for another reason-in some cases matings between close relatives temporarily increase inbreeding depression in autotetraploids by increasing the frequency of the heterozygous genotype harboring the most harmful mutations. When neo-autotetraploids are formed by few individuals, inbreeding depression is dramatically reduced, given extensive masking of harmful mutations following whole genome duplication. This effect persists as nascent tetraploids reach mutation-selection-drift balance, providing a transient period of permissive conditions favoring the evolution of selfing.
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Affiliation(s)
- Nathan C Layman
- School of Biological Sciences, Washington State University, Pullman, Washington 99164
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, Pullman, Washington 99164
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13
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Goodwillie C, Weber JJ. The best of both worlds? A review of delayed selfing in flowering plants. AMERICAN JOURNAL OF BOTANY 2018; 105:641-655. [PMID: 29630718 DOI: 10.1002/ajb2.1045] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 01/17/2018] [Indexed: 05/27/2023]
Abstract
PREMISE OF STUDY In a seminal body of theory, Lloyd showed that the fitness consequences of selfing will depend on its timing in anthesis. Selfing that occurs after opportunities for outcrossing or pollen dispersal can provide reproductive assurance when pollinators are limited and is expected to incur little cost, even when inbreeding depression is high. As a result, delayed selfing is often interpreted as a "best-of-both-worlds" mating system that combines the advantages of selfing and outcrossing. METHODS We surveyed 65 empirical studies of delayed selfing, recording floral mechanisms and examining information on inbreeding depression, autofertility, and other parameters to test the support for delayed selfing as a best-of-both-worlds strategy. KEY RESULTS Phylogenetic distribution of the diverse floral mechanisms suggests that some basic floral structures may predispose plant taxa to evolve delayed selfing. Delayed selfing appears to serve as a best-of-both-worlds strategy in some but not all species. While the capacity for autonomous selfing is often high, it is lower, in some cases, than in related species with earlier modes of selfing. In other delayed-selfers, low inbreeding depression and reduced investment in corollas and pollen suggest limited benefits from outcrossing. CONCLUSIONS Despite a growing literature on the subject, experimental evidence for delayed selfing is limited and major gaps in knowledge remain, particularly with respect to the stability of delayed selfing and the conditions that may favor transitions between delayed and earlier selfing. Finally, we suggest a potential role of delayed selfing in facilitating transitions from self-incompatibility to selfing.
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Affiliation(s)
- Carol Goodwillie
- East Carolina University, Department of Biology, Howell Science Building, Greenville, NC, 27858
| | - Jennifer J Weber
- Southeast Missouri State University, Department of Biology, One University Plaza, MS 6200, Cape Girardeau, MO, 63701
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14
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Voillemot M, Rougemont Q, Roux C, Pannell JR. The divergence history of the perennial plant Linaria cavanillesii
confirms a recent loss of self-incompatibility. J Evol Biol 2017; 31:136-147. [DOI: 10.1111/jeb.13209] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 11/03/2017] [Accepted: 11/07/2017] [Indexed: 11/30/2022]
Affiliation(s)
- M. Voillemot
- Department of Ecology and Evolution; Biophore/Sorge; University of Lausanne; Lausanne Switzerland
| | - Q. Rougemont
- Institut de Biologie Intégrative et des Systèmes (IBIS); University of Laval; Québec City Québec Canada
| | - C. Roux
- Department of Ecology and Evolution; Biophore/Sorge; University of Lausanne; Lausanne Switzerland
- Unité Evo-Eco-Paléo (EEP) - UMR 8198; CNRS; Université de Lille Sciences et Technologies; Villeneuve d'Ascq Cedex France
| | - J. R. Pannell
- Department of Ecology and Evolution; Biophore/Sorge; University of Lausanne; Lausanne Switzerland
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15
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Barrett SC, Harder LD. The Ecology of Mating and Its Evolutionary Consequences in Seed Plants. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2017. [DOI: 10.1146/annurev-ecolsys-110316-023021] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Spencer C.H. Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
| | - Lawrence D. Harder
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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16
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Kerbs B, Ressler J, Kelly JK, Mort ME, Santos-Guerra A, Gibson MJS, Caujapé-Castells J, Crawford DJ. The potential role of hybridization in diversification and speciation in an insular plant lineage: insights from synthetic interspecific hybrids. AOB PLANTS 2017; 9:plx043. [PMID: 29225761 PMCID: PMC5714139 DOI: 10.1093/aobpla/plx043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 08/25/2017] [Indexed: 05/17/2023]
Abstract
Hybridization is recognized as an important process in plant evolution, and this may be particularly true for island plants where several biotic and abiotic factors facilitate interspecific hybridization. Although rarely done, experimental studies could provide insights into the potential of natural hybridization to generate diversity when species come into contact in the dynamic island setting. The potential of hybridization to generate morphological variation was analysed within and among 12 families (inbred lines) of an F4 hybrid generation between two species of Tolpis endemic to the Canary Islands. Combinations of characters not seen in the parents were present in hybrids. Several floral and vegetative characters were transgressive relative to their parents. Morphometric studies of floral, vegetative and fruit characters revealed that several F4 families were phenotypically distinct from other families, and from their parents. The study demonstrates that morphologically distinct pollen-fertile lines, potentially worthy of taxonomic recognition if occurring in nature, can be generated in four generations. The ability of the hybrid lines to set self-seed would reduce gene flow among the lines, and among the hybrids and their parental species. Selfing would also facilitate the fixation of characters within each of the lines. Overall, the results show the considerable potential of hybridization for generating diversity and distinct phenotypes in island lineages.
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Affiliation(s)
- Benjamin Kerbs
- Department of Biological Sciences, Emporia State University, Emporia, KS 66801, USA
| | - Jacob Ressler
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - John K Kelly
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS 66045-7534, USA
| | - Mark E Mort
- Department of Ecology & Evolutionary Biology, University of Kansas, Lawrence, KS 66045-7534, USA
| | - Arnoldo Santos-Guerra
- Calle Guaidil 16, Urbanización Tamarco, 38280 Tegueste, Tenerife, Canary Islands, Spain
| | | | - Juli Caujapé-Castells
- Jardín Botánico 13 Canario “Viera y Clavijo”-Unidad Asociada al CSIC (Cabildo de Gran Canaria), Camino del palmeral 14 15 (Tafira Alta), 35017 Las Palmas de Gran Canaria, Spain
| | - Daniel J Crawford
- Department of Ecology & Evolutionary Biology, and the Biodiversity Institute, University of Kansas, Lawrence, KS 66045-7534, USA
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17
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Toräng P, Vikström L, Wunder J, Wötzel S, Coupland G, Ågren J. Evolution of the selfing syndrome: Anther orientation and herkogamy together determine reproductive assurance in a self-compatible plant. Evolution 2017; 71:2206-2218. [PMID: 28722132 DOI: 10.1111/evo.13308] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/22/2017] [Accepted: 06/22/2017] [Indexed: 01/04/2023]
Abstract
Capacity for autonomous self-fertilization provides reproductive assurance, has evolved repeatedly in the plant kingdom, and typically involves several changes in flower morphology and development (the selfing syndrome). Yet, the relative importance of different traits and trait combinations for efficient selfing and reproductive success in pollinator-poor environments is poorly known. In a series of experiments, we tested the importance of anther-stigma distance and the less studied trait anther orientation for efficiency of selfing in the perennial herb Arabis alpina. Variation in flower morphology among eight self-compatible European populations was correlated with efficiency of self-pollination and with pollen limitation in a common-garden experiment. To examine whether anther-stigma distance and anther orientation are subject to directional and/or correlational selection, and whether this is because these traits affect pollination success, we planted a segregating F2 population at two native field sites. Selection strongly favored a combination of introrse anthers and reduced anther-stigma distance at a site where pollinator activity was low, and supplemental hand-pollination demonstrated that this was largely because of their effect on securing self-pollination. The results suggest that concurrent shifts in more than one trait can be crucial for the evolution of efficient self-pollination and reproductive assurance in pollinator-poor habitats.
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Affiliation(s)
- Per Toräng
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden.,School of Bioscience, University of Skövde, Box 408, SE-541 28, Skövde, Sweden
| | - Linus Vikström
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
| | - Jörg Wunder
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl von Linné Weg 10, 50829, Cologne, Germany
| | - Stefan Wötzel
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl von Linné Weg 10, 50829, Cologne, Germany
| | - George Coupland
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Carl von Linné Weg 10, 50829, Cologne, Germany
| | - Jon Ågren
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
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18
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Harkness A. Digest: Prudent self-denial: The advantage of incompatibility in Leavenworthia alabamica. Evolution 2017; 71:1114-1115. [PMID: 28240770 DOI: 10.1111/evo.13214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 02/08/2017] [Indexed: 12/01/2022]
Affiliation(s)
- Alexander Harkness
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Minneapolis, Minnesota, 55455
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