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Edwards CE, Bassüner B, Williams BR. Population Genetic Analysis of the Threatened Plant Leavenworthia exigua var. laciniata (Brassicaceae) Reveals Virtually No Genetic Diversity and a Unique Mating System. FRONTIERS IN CONSERVATION SCIENCE 2022. [DOI: 10.3389/fcosc.2022.831085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Leavenworthia (Brassicaceae) has served as a model group for investigating the evolution of mating systems in plants, yet several Leavenworthia species remain understudied. One such taxon is Leavenworthia exigua var. laciniata, one of three varieties of L. exigua, a winter-annual plant endemic to the central United States. Because L. exigua var. laciniata occupies a narrow geographic range and is experiencing major habitat loss, it was recently listed as threatened; however, little is known about its genetic diversity and implications for conservation. We conducted a range-wide population genetic study of L. exigua var. laciniata and L. exigua var. exigua to understand: (1) levels of genetic diversity within and among populations, (2) whether L. exigua var. laciniata is genetically distinct from L. exigua var. exigua, and (3) implications for conservation. L. exigua var. laciniata showed identical genotypes at all 16 microsatellite loci across most of its range, fixed heterozygosity at some loci, and significant heterozygote excesses, consistent with a lack of recombination associated with an asexual mating system, which has not been documented previously in Leavenworthia. Because L. exigua var. laciniata is an annual and the same genotype occurs across multiple populations, asexuality may be caused by apomixis, asexual reproduction via seed. In contrast, most populations of L. exigua var. exigua demonstrated population genetic patterns consistent with a self-compatible mating system. Because L. exigua var. laciniata is morphologically, geographically, and genetically distinct, it should be recognized as an evolutionarily significant unit for conservation. We recommend maintaining large population sizes to conserve evolutionary potential in L. exigua var. laciniata, as the likelihood that facultative sexual reproduction may occur may be greater in larger populations. Additional research in L. exigua var. laciniata is needed to confirm the occurrence of asexuality and apomixis, clarify its reproductive isolation from other taxa, and to understand whether it exhibits residual sexual reproduction, epigenetic variation, or phenotypic plasticity to help it persist in response to environmental variation. In the future, L. exigua var. laciniata may serve as an important model in which to investigate the conservation of threatened plant species with little genetic variation in a changing climate.
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Seguí J, Hervías-Parejo S, Traveset A. Selective forces on the maintenance of outcrossing in an almost exclusively cleistogamous violet species. AMERICAN JOURNAL OF BOTANY 2021; 108:2452-2463. [PMID: 34622956 DOI: 10.1002/ajb2.1768] [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: 01/29/2021] [Accepted: 09/01/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Cleistogamous species constitute interesting study systems to resolve the longstanding question of how outcrossing is maintained given that seed production is ensured through selfing. In this work, we investigate the selective forces that allow the persistence of producing self-pollinated cleistogamous (CL) and chasmogamous (CH) flowers in Viola jaubertiana Marès & Vigin. METHODS We monitored three populations at different elevation for two years, and studied the flowering phenology and the relative contribution of each flower morph to parental fitness. We tested whether allocation to CH and CL flowers differed across populations and if it covaried with herbivory and water stress conditions. We also performed hand-pollination and bagging experiments in CH flowers to estimate inbreeding depression and heterosis. RESULTS The CH flowers open in winter under unfavorable conditions for pollination, show high pollen limitation and no-delayed selfing, and thus produce a low amount of seeds. Conversely, CL flowers appear in early spring, are physiologically cheaper to produce (i.e., dry weight is 3.4 times lower than that of CH flowers), and yield approximately 100 times more seeds than CH flowers. The CH flowers were favored under water stress and low herbivory. Crosses between populations showed up to 25% greater fitness than those within populations. CONCLUSIONS Despite the great pollen limitation in CH flowers, we suggest that the interaction among different environmental determinants and heterosis are probably sufficient forces to maintain chasmogamy in this long-lived species, reducing deleterious fixed mutations in the selfed lines.
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Affiliation(s)
- Jaume Seguí
- Department of Global Change, Mediterranean Institute for Advanced Studies (CSIC-UIB), C/Miquel Marquès 21, 07190-Esporles, Mallorca, Balearic Islands, Spain
| | - Sandra Hervías-Parejo
- Department of Global Change, Mediterranean Institute for Advanced Studies (CSIC-UIB), C/Miquel Marquès 21, 07190-Esporles, Mallorca, Balearic Islands, Spain
| | - Anna Traveset
- Department of Global Change, Mediterranean Institute for Advanced Studies (CSIC-UIB), C/Miquel Marquès 21, 07190-Esporles, Mallorca, Balearic Islands, Spain
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Hodgins KA, Yeaman S. Mating system impacts the genetic architecture of adaptation to heterogeneous environments. THE NEW PHYTOLOGIST 2019; 224:1201-1214. [PMID: 31505030 DOI: 10.1111/nph.16186] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 08/27/2019] [Indexed: 06/10/2023]
Abstract
Self-fertilisation has consequences for variation across the genome as it reduces effective population size, effect recombination rates and pollen flow, with implications for local adaptation. We conducted simulations of divergent stabilising selection on a quantitative trait with drift, pollen flow, mutation, recombination and different outcrossing rates. We quantified trait divergence and the genetic architecture of adaptation. We conducted an FST outlier analysis to identify candidate loci and quantified the impact of mating system on detectability. Selfing promoted trait divergence mainly through reductions in pollen flow. Moreover, trait architecture became more diffuse with selfing. Average effect size of trait loci was lower, while the number of loci, and their clustering distance increased. The genetic architecture of selfers was also more diffuse than outcrossers for equivalent migration rates. However, when deleterious alleles were included, architectures became more concentrated in selfers, likely to be because of reductions in population size caused by mutational meltdown and impacts of background selection on Ne . Our simulations demonstrate that mating system has important impacts on adaptive divergence of traits and the genetic landscape underlying that divergence. Selfing has a significant effect on detectability of regions of the genome important for adaptation because of neutral divergence and diffuse trait architecture.
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Affiliation(s)
- Kathryn A Hodgins
- School of Biological Sciences, Monash University - Clayton Campus, Building 17, Wellington Road, Clayton, Victoria, 3800, Australia
| | - Sam Yeaman
- Department of Biological Sciences, University of Calgary, 507 Campus Drive NW, Calgary, AB, T2N 4S8, Canada
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Oakley CG, Lundemo S, Ågren J, Schemske DW. Heterosis is common and inbreeding depression absent in natural populations of
Arabidopsis thaliana. J Evol Biol 2019; 32:592-603. [DOI: 10.1111/jeb.13441] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 02/23/2019] [Accepted: 03/11/2019] [Indexed: 01/09/2023]
Affiliation(s)
| | - Sverre Lundemo
- Plant Ecology and Evolution Department of Ecology and Genetics Evolutionary Biology Centre Uppsala University Uppsala Sweden
| | - Jon Ågren
- Plant Ecology and Evolution Department of Ecology and Genetics Evolutionary Biology Centre Uppsala University Uppsala Sweden
| | - Douglas W. Schemske
- Department of Plant Biology W. K. Kellogg Biological Station Michigan State University East Lansing Michigan
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Harkness A, Brandvain Y, Goldberg EE. The evolutionary response of mating system to heterosis. J Evol Biol 2019; 32:476-490. [DOI: 10.1111/jeb.13430] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 01/28/2019] [Accepted: 02/04/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Alexander Harkness
- Department of Ecology, Evolution, and BehaviorUniversity of Minnesota St. Paul Minnesota
| | - Yaniv Brandvain
- Department of Plant and Microbial BiologyUniversity of Minnesota St. Paul Minnesota
| | - Emma E. Goldberg
- Department of Ecology, Evolution, and BehaviorUniversity of Minnesota St. Paul Minnesota
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6
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Charlesworth B. Mutational load, inbreeding depression and heterosis in subdivided populations. Mol Ecol 2018; 27:4991-5003. [DOI: 10.1111/mec.14933] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/05/2018] [Accepted: 10/08/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Brian Charlesworth
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
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Voillemot M, Pannell JR. Inbreeding depression is high in a self-incompatible perennial herb population but absent in a self-compatible population showing mixed mating. Ecol Evol 2017; 7:8535-8544. [PMID: 29075469 PMCID: PMC5648656 DOI: 10.1002/ece3.3354] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/24/2017] [Indexed: 01/08/2023] Open
Abstract
High inbreeding depression is thought to be one of the major factors preventing evolutionary transitions in hermaphroditic plants from self‐incompatibility (SI) and outcrossing toward self‐compatibility (SC) and selfing. However, when selfing does evolve, inbreeding depression can be quickly purged, allowing the evolution of complete self‐fertilization. In contrast, populations that show intermediate selfing rates (a mixed‐mating system) typically show levels of inbreeding depression similar to those in outcrossing species, suggesting that selection against inbreeding might be responsible for preventing the transition toward complete self‐fertilization. By implication, crosses among populations should reveal patterns of heterosis for mixed‐mating populations that are similar to those expected for outcrossing populations. Using hand‐pollination crosses, we compared levels of inbreeding depression and heterosis between populations of Linaria cavanillesii (Plantaginaceae), a perennial herb showing contrasting mating systems. The SI population showed high inbreeding depression, whereas the SC population displaying mixed mating showed no inbreeding depression. In contrast, we found that heterosis based on between‐population crosses was similar for SI and SC populations. Our results are consistent with the rapid purging of inbreeding depression in the derived SC population, despite the persistence of mixed mating. However, the maintenance of outcrossing after a transition to SC is inconsistent with the prediction that populations that have purged their inbreeding depression should evolve toward complete selfing, suggesting that the transition to SC in L. cavanillesii has been recent. SC in L. cavanillesii thus exemplifies a situation in which the mating system is likely not at an equilibrium with inbreeding depression.
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Affiliation(s)
- Marie Voillemot
- Department of Ecology and Evolution University of Lausanne Lausanne Switzerland
| | - John R Pannell
- Department of Ecology and Evolution University of Lausanne Lausanne Switzerland
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Spigler RB, Theodorou K, Chang S. Inbreeding depression and drift load in small populations at demographic disequilibrium. Evolution 2016; 71:81-94. [DOI: 10.1111/evo.13103] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 11/27/2022]
Affiliation(s)
- Rachel B. Spigler
- Department of Biology Temple University 1900 N. 12th Street Philadelphia Pennsylvania 19122
| | - Konstantinos Theodorou
- Biodiversity Conservation Laboratory, Department of Environment, University of the Aegean University Hill 81100 Mytilene Greece
| | - Shu‐Mei Chang
- Department of Plant Biology University of Georgia 2502 Miller Plant Sciences Athens Georgia 30602–7271
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Oakley CG, Spoelhof JP, Schemske DW. Increased heterosis in selfing populations of a perennial forb. AOB PLANTS 2015; 7:plv122. [PMID: 26507567 PMCID: PMC4671326 DOI: 10.1093/aobpla/plv122] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 10/09/2015] [Indexed: 06/05/2023]
Abstract
Quantifying the importance of random genetic drift in natural populations is central to understanding the potential limits to natural selection. One approach is to estimate the magnitude of heterosis, the increased fitness of progeny derived from crosses between populations relative to crosses within populations caused by the heterozygous masking of deleterious recessive or nearly recessive alleles that have been fixed by drift within populations. Self-fertilization is expected to reduce the effective population size by half relative to outcrossing, and population bottlenecks may be common during the transition to selfing. Therefore, chance fixation of deleterious alleles due to drift in selfing populations should increase heterosis between populations. Increased homozygosity due to fixation or loss of alleles should also decrease inbreeding depression within populations. Most populations of the perennial herb Arabidopsis lyrata ssp. lyrata are self-incompatible (SI), but several have evolved self-compatibility and are highly selfing. We quantified heterosis and inbreeding depression in two predominantly self-compatible (SC) and seven SI populations in a field common garden experiment within the species' native range and examined the correlation between these metrics to gauge the similarity in their genetic basis. We measured proportion germination in the lab, and survival and fecundity (flower and seed production) for 2 years in the field, and calculated estimates of cumulative fitness. We found 7.2-fold greater heterosis in SC compared with SI populations, despite substantial heterosis in SI populations (56 %). Inbreeding depression was >61 %, and not significantly different between SC and SI populations. There was no correlation between population estimates of heterosis and inbreeding depression, suggesting that they have somewhat different genetic bases. Combined with other sources of information, our results suggest a history of bottlenecks in all of these populations. The bottlenecks in SC populations may have been severe, but their strong inbreeding depression remains enigmatic.
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Affiliation(s)
- Christopher G Oakley
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824-1312, USA
| | - Jonathan P Spoelhof
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824-1312, USA
| | - Douglas W Schemske
- Department of Plant Biology and W. K. Kellogg Biological Station, Michigan State University, East Lansing, MI 48824, USA
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Genetic and fitness consequences of interpopulation mating in Dianthus guliae Janka: conservation implications for severely depleted and isolated plant populations. CONSERV GENET 2015. [DOI: 10.1007/s10592-015-0727-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Outbreeding Depression in Atlantic Salmon Revealed by Hypoxic Stress During Embryonic Development. Evol Biol 2014. [DOI: 10.1007/s11692-014-9289-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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12
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Oakley CG. Small effective size limits performance in a novel environment. Evol Appl 2013; 6:823-831. [PMID: 29387168 PMCID: PMC5779127 DOI: 10.1111/eva.12068] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 03/06/2013] [Indexed: 02/03/2023] Open
Abstract
Understanding what limits or facilitates species' responses to human‐induced habitat change can provide insight for the control of invasive species and the conservation of small populations, as well as an arena for studying adaptation to realistic novel environments. Small effective size of ancestral populations could limit the establishment in, or response to, a novel or altered habitat because of low genetic variation for ecologically important traits, and/or because small populations harbor fixed deleterious mutations. I estimated the fitness of individuals from populations of the endangered plant Hypericum cumulicola, of known census and effective size, transplanted into native scrub habitat and unpaved roadsides, which are a novel habitat for this species. I found a significant positive relationship between estimates of population size and mean fitness, but only in the novel roadside habitat. Fitness was more than 200% greater in the roadside habitat than the scrub, mostly due to increased fecundity. These results combined with previous estimates of heterosis in this species suggest that fixed deleterious mutations could contribute to lower fitness of field transplants from small populations in the novel environment.
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Mullarkey AA, Byers DL, Anderson RC. Inbreeding depression and partitioning of genetic load in the invasive biennial Alliaria petiolata (Brassicaceae). AMERICAN JOURNAL OF BOTANY 2013; 100:509-518. [PMID: 23445827 DOI: 10.3732/ajb.1200403] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
PREMISE OF THE STUDY Invasive species are nonnative species that enter novel environments, establish sustained populations, and can negatively impact native species. Here we assess a potential weakness of invasive species (genetic load) and show how species might overcome genetic barriers. Colonization of novel habitats by invasive species typically involves few individuals, exposing populations to founder effects. We empirically tested a central Illinois population of an invasive biennial plant, Alliaria petiolata, for evidence of a founder effect by assessing the pattern of genetic load. • METHODS To estimate genetic load, we assayed offspring from three cross types (self-pollinated, outcrossed within- and between-populations) in a greenhouse. Vegetative and reproductive traits were measured on first-year plants grown with or without intraspecific competition. • KEY RESULTS We found substantial genetic load in this population of A. petiolata, which can mostly be attributed to genetic drift (founder effect) and not inbreeding depression. Between-population heterosis was expressed more than inbreeding depression under intraspecific competition. • CONCLUSIONS Inbreeding may be adaptive for A. petiolata in its introduced range by providing reproductive assurance, with limited inbreeding load. Nevertheless, most of the genetic load in this population of A. petiolata is due to fixation of deleterious alleles. Drift load is expected, given that this population is near the edge of its continuous geographic range in highly fragmented habitats, and gene flow between isolated populations is likely highly limited. Preventing additional introduction and movement of propagules between isolated local populations should reduce heterosis and A. petiolata competitiveness.
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Affiliation(s)
- Alicia A Mullarkey
- School of Biological Sciences, Campus Box 4120, Illinois State University, Normal, IL 61790-4120, USA
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Vitalis R, Rousset F, Kobayashi Y, Olivieri I, Gandon S. The joint evolution of dispersal and dormancy in a metapopulation with local extinctions and kin competition. Evolution 2013; 67:1676-91. [PMID: 23730761 DOI: 10.1111/evo.12069] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 01/17/2013] [Indexed: 12/11/2022]
Abstract
Dispersal and dormancy are two strategies that allow recolonization of empty patches and escape from kin competition. Because they presumably respond to similar evolutionary forces, it is tempting to consider that these strategies may substitute for each other. Yet in order to predict the outcome of the evolution of dispersal and dormancy, and to characterize the emerging covariation between both traits, it is necessary to consider models where dispersal and dormancy evolve jointly. Here, we analyze the evolution of dispersal and dormancy as a function of direct fitness costs, environmental variation, and competition among relatives. We consider two scenarios depending on whether the rates of dormancy for philopatric and dispersed individuals are constrained to be the same (unconditional dormancy) or allowed to be different (conditional dormancy). We show that only philopatric individuals should enter dormancy, at a rate increasing with increasing rates of local extinction and decreasing population sizes. When dormancy and dispersal evolve jointly, we observe a wide range of evolutionary outcomes. In particular, we find that the pattern of covariation between the evolutionarily stable rates of dispersal and dormancy is molded by the rate of extinction and the local population size.
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Affiliation(s)
- Renaud Vitalis
- Institut des Sciences de l'Évolution, UMR 5554, CNRS, Université Montpellier 2, Montpellier cedex 5, Place Eugène Bataillon, France.
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Oakley CG, Winn AA. Effects of population size and isolation on heterosis, mean fitness, and inbreeding depression in a perennial plant. THE NEW PHYTOLOGIST 2012; 196:261-270. [PMID: 22816555 DOI: 10.1111/j.1469-8137.2012.04240.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
• In small isolated populations, genetic drift is expected to increase chance fixation of partly recessive, mildly deleterious mutations, reducing mean fitness and inbreeding depression within populations and increasing heterosis in outcrosses between populations. • We estimated relative effective sizes and migration among populations and compared mean fitness, heterosis, and inbreeding depression for eight large and eight small populations of a perennial plant on the basis of fitness of progeny produced by hand pollinations within and between populations. • Migration was limited, and, consistent with expectations for drift, mean fitness was 68% lower in small populations; heterosis was significantly greater for small (mean = 70%, SE = 14) than for large populations (mean = 7%, SE = 27); and inbreeding depression was lower, although not significantly so, in small (mean = -0.29%, SE = 28) than in large (mean = 0.28%, SE = 23) populations. • Genetic drift promotes fixation of deleterious mutations in small populations, which could threaten their persistence. Limited migration will exacerbate drift, but data on migration and effective population sizes in natural populations are scarce. Theory incorporating realistic variation in population size and patterns of migration could better predict genetic threats to small population persistence.
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Affiliation(s)
- Christopher G Oakley
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
- Present address: Department of Plant Biology, Michigan State University, East Lansing, MI 48824-1312, USA
| | - Alice A Winn
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
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Coutellec MA, Caquet T. Heterosis and inbreeding depression in bottlenecked populations: a test in the hermaphroditic freshwater snail Lymnaea stagnalis. J Evol Biol 2011; 24:2248-57. [PMID: 21767319 DOI: 10.1111/j.1420-9101.2011.02355.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Small population size is expected to induce heterosis, due to the random fixation and accumulation of mildly deleterious mutations, whereas within-population inbreeding depression should decrease due to increased homozygosity. Population bottlenecks, although less effective, may have similar consequences. We tested this hypothesis in the self-fertile freshwater snail Lymnaea stagnalis, by subjecting experimental populations to a single bottleneck of varied magnitude. Although patterns were not strong, heterosis was significant in the most severely bottlenecked populations, under stressful conditions. This was mainly due to hatching rate, suggesting that early acting and highly deleterious alleles were involved. Although L. stagnalis is a preferential outcrosser, inbreeding depression was very low and showed no clear relationship with bottleneck size. In the less reduced populations, inbreeding depression for hatching success increased under high inbreeding. This may be consistent with the occurence of synergistic epistasis between fitness loci, which may contribute to favour outcrossing in L. stagnalis.
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Affiliation(s)
- M-A Coutellec
- INRA, UMR 0985 ESE, Agrocampus-Ouest, Equipe Ecotoxicologie et Qualité des Milieux Aquatiques, Rennes Cedex, France.
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Effects of outcrossing in fragmented populations of the primarily selfing forest herb Geum urbanum. Evol Ecol 2010. [DOI: 10.1007/s10682-010-9395-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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19
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Harder LD, Aizen MA. Floral adaptation and diversification under pollen limitation. Philos Trans R Soc Lond B Biol Sci 2010; 365:529-43. [PMID: 20047878 DOI: 10.1098/rstb.2009.0226] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pollen limitation (PL) of seed production creates unique conditions for reproductive adaptation by angiosperms, in part because, unlike under ovule or resource limitation, floral interactions with pollen vectors can contribute to variation in female success. Although the ecological and conservation consequences of PL have received considerable attention in recent times, its evolutionary implications are poorly appreciated. To identify general influences of PL on reproductive adaptation compared with those under other seed-production limits and their implications for evolution in altered environments, we derive a model that incorporates pollination and post-pollination aspects of PL. Because PL always favours increased ovule fertilization, even when population dynamics are not seed limited, it should pervasively influence selection on reproductive traits. Significantly, under PL the intensity of inbreeding does not determine whether outcrossing or autonomous selfing can evolve, although it can affect which response is most likely. Because the causes of PL are multifaceted in both natural and anthropogenically altered environments, the possible outcrossing solutions are diverse and context dependent, which may contribute to the extensive variety of angiosperm reproductive characteristics. Finally, the increased adaptive options available under PL may be responsible for positive global associations between it and angiosperm diversity.
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Affiliation(s)
- Lawrence D Harder
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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Guillaume F, Perrin N. Inbreeding load, bet hedging, and the evolution of sex-biased dispersal. Am Nat 2009; 173:536-41. [PMID: 19243259 DOI: 10.1086/597218] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Abstract: Inbreeding load affects not only the average fecundity of philopatric individuals but also its variance. From bet-hedging theory, this should add further dispersal pressures to those stemming from the mere avoidance of inbreeding. Pressures on both sexes are identical under monogamy or promiscuity. Under polygyny, by contrast, the variance in reproductive output decreases with dispersal rate in females but increases in males, which should induce a female-biased dispersal. To test this prediction, we performed individual-based simulations. From our results, a female-biased dispersal indeed emerges as both polygyny and inbreeding load increase. We conclude that sex-biased dispersal may be selected for as a bet-hedging strategy.
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Affiliation(s)
- Frédéric Guillaume
- Department of Zoology, 6270 University Boulevard, University of British Columbia, Vancouver, British Columbia, Canada.
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22
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Stochasticity in evolution. Trends Ecol Evol 2009; 24:157-65. [DOI: 10.1016/j.tree.2008.09.014] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 09/24/2008] [Accepted: 09/25/2008] [Indexed: 11/30/2022]
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Jaquiéry J, Guillaume F, Perrin N. Predicting the deleterious effects of mutation load in fragmented populations. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2009; 23:207-218. [PMID: 18847439 DOI: 10.1111/j.1523-1739.2008.01052.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Human-induced habitat fragmentation constitutes a major threat to biodiversity. Both genetic and demographic factors combine to drive small and isolated populations into extinction vortices. Nevertheless, the deleterious effects of inbreeding and drift load may depend on population structure, migration patterns, and mating systems and are difficult to predict in the absence of crossing experiments. We performed stochastic individual-based simulations aimed at predicting the effects of deleterious mutations on population fitness (offspring viability and median time to extinction) under a variety of settings (landscape configurations, migration models, and mating systems) on the basis of easy-to-collect demographic and genetic information. Pooling all simulations, a large part (70%) of variance in offspring viability was explained by a combination of genetic structure (F(ST)) and within-deme heterozygosity (H(S)). A similar part of variance in median time to extinction was explained by a combination of local population size (N) and heterozygosity (H(S)). In both cases the predictive power increased above 80% when information on mating systems was available. These results provide robust predictive models to evaluate the viability prospects of fragmented populations.
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Affiliation(s)
- J Jaquiéry
- Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
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