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Hitchcock TJ, Gardner A. Sexual antagonism in sequential hermaphrodites. Proc Biol Sci 2023; 290:20232222. [PMID: 37989243 PMCID: PMC10688264 DOI: 10.1098/rspb.2023.2222] [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: 09/30/2023] [Accepted: 10/30/2023] [Indexed: 11/23/2023] Open
Abstract
Females and males may have distinct phenotypic optima, but share essentially the same complement of genes, potentially leading to trade-offs between attaining high fitness through female versus male reproductive success. Such sexual antagonism may be particularly acute in hermaphrodites, where both reproductive strategies are housed within a single individual. While previous models have focused on simultaneous hermaphroditism, we lack theory for how sexual antagonism may play out under sequential hermaphroditism, which has the additional complexities of age-structure. Here, we develop a formal theory of sexual antagonism in sequential hermaphrodites. First, we construct a general theoretical overview of the problem, then consider different types of sexually antagonistic and life-history trade-offs, under different modes of genetic inheritance (autosomal or cytoplasmic), and different forms of sequential hermaphroditism (protogynous, protoandrous or bidirectional). Finally, we provide a concrete illustration of these general patterns by developing a two-stage two-sex model, which yields conditions for both invasion of sexually antagonistic alleles and maintenance of sexually antagonistic polymorphisms.
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Affiliation(s)
- Thomas J. Hitchcock
- RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN, Wako, Saitama 351-0198, Japan
- School of Biology, University of St Andrews, St Andrews, Fife KY16 9TH, UK
| | - Andy Gardner
- School of Biology, University of St Andrews, St Andrews, Fife KY16 9TH, UK
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2
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Pla S, Benvenuto C, Capellini I, Piferrer F. Switches, stability and reversals in the evolutionary history of sexual systems in fish. Nat Commun 2022; 13:3029. [PMID: 35637181 PMCID: PMC9151764 DOI: 10.1038/s41467-022-30419-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 04/29/2022] [Indexed: 11/09/2022] Open
Abstract
Sexual systems are highly diverse and have profound consequences for population dynamics and resilience. Yet, little is known about how they evolved. Using phylogenetic Bayesian modelling and a sample of 4614 species, we show that gonochorism is the likely ancestral condition in teleost fish. While all hermaphroditic forms revert quickly to gonochorism, protogyny and simultaneous hermaphroditism are evolutionarily more stable than protandry. In line with theoretical expectations, simultaneous hermaphroditism does not evolve directly from gonochorism but can evolve slowly from sequential hermaphroditism, particularly protandry. We find support for the predictions from life history theory that protogynous, but not protandrous, species live longer than gonochoristic species and invest the least in male gonad mass. The distribution of teleosts' sexual systems on the tree of life does not seem to reflect just adaptive predictions, suggesting that adaptations alone may not fully explain why some sexual forms evolve in some taxa but not others (Williams' paradox). We propose that future studies should incorporate mating systems, spawning behaviours, and the diversity of sex determining mechanisms. Some of the latter might constrain the evolution of hermaphroditism, while the non-duality of the embryological origin of teleost gonads might explain why protogyny predominates over protandry in teleosts.
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Affiliation(s)
- Susanna Pla
- Institut de Ciències del Mar, Spanish National Research Council (CSIC), Barcelona, Spain
| | - Chiara Benvenuto
- School of Science, Engineering and Environment, University of Salford, Salford, UK
| | | | - Francesc Piferrer
- Institut de Ciències del Mar, Spanish National Research Council (CSIC), Barcelona, Spain.
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3
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Viard F, Riginos C, Bierne N. Anthropogenic hybridization at sea: three evolutionary questions relevant to invasive species management. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190547. [PMID: 32654643 PMCID: PMC7423285 DOI: 10.1098/rstb.2019.0547] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2020] [Indexed: 12/24/2022] Open
Abstract
Species introductions promote secondary contacts between taxa with long histories of allopatric divergence. Anthropogenic contact zones thus offer valuable contrasts to speciation studies in natural systems where past spatial isolations may have been brief or intermittent. Investigations of anthropogenic hybridization are rare for marine animals, which have high fecundity and high dispersal ability, characteristics that contrast to most terrestrial animals. Genomic studies indicate that gene flow can still occur after millions of years of divergence, as illustrated by invasive mussels and tunicates. In this context, we highlight three issues: (i) the effects of high propagule pressure and demographic asymmetries on introgression directionality, (ii) the role of hybridization in preventing introduced species spread, and (iii) the importance of postzygotic barriers in maintaining reproductive isolation. Anthropogenic contact zones offer evolutionary biologists unprecedented large scale hybridization experiments. In addition to breaking the highly effective reproductive isolating barrier of spatial segregation, they allow researchers to explore unusual demographic contexts with strong asymmetries. The outcomes are diverse, from introgression swamping to strong barriers to gene flow, and lead to local containment or widespread invasion. These outcomes should not be neglected in management policies of marine invasive species. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
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Affiliation(s)
- Frédérique Viard
- AD2M, Station Biologique de Roscoff, Sorbonne Université, CNRS, Roscoff, France
| | - Cynthia Riginos
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Nicolas Bierne
- ISEM, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
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4
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Pla S, Benvenuto C, Capellini I, Piferrer F. A phylogenetic comparative analysis on the evolution of sequential hermaphroditism in seabreams (Teleostei: Sparidae). Sci Rep 2020; 10:3606. [PMID: 32107416 PMCID: PMC7046777 DOI: 10.1038/s41598-020-60376-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 01/28/2020] [Indexed: 01/25/2023] Open
Abstract
The Sparids are an ideal group of fishes in which to study the evolution of sexual systems since they exhibit a great sexual diversity, from gonochorism (separate sexes) to protandrous (male-first) and protogynous (female-first) sequential hermaphroditism (sex change). According to the size-advantage model (SAM), selection should favour sex change when the second sex achieves greater reproductive success at a larger body size than the first sex. Using phylogenetic comparative methods and a sample of 68 sparid species, we show that protogyny and protandry evolve from gonochorism but evolutionary transitions between these two forms of sequential hermaphroditism are unlikely to happen. Using male gonadosomatic index (GSI) as a measure of investment in gametes and proxy for sperm competition, we find that, while gonochoristic and protogynous species support the predictions of SAM, protandrous species do not, as they exhibit higher GSI values than expected even after considering mating systems and spawning modes. We suggest that small males of protandrous species have to invest disproportionally more in sperm production than predicted not only when spawning in aggregations, with high levels of sperm competition, but also when spawning in pairs due to the need to fertilize highly fecund females, much larger than themselves. We propose that this compensatory mechanism, together with Bateman’s principles in sequential hermaphrodites, should be formally incorporated in the SAM.
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Affiliation(s)
- Susanna Pla
- Institut de Ciències del Mar, Spanish National Research Council (CSIC), Barcelona, Spain
| | - Chiara Benvenuto
- Ecosystems and Environment Research Centre, School of Science, Engineering and Environment, University of Salford, Salford, UK
| | - Isabella Capellini
- School of Biological Sciences, Queen's University of Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
| | - Francesc Piferrer
- Institut de Ciències del Mar, Spanish National Research Council (CSIC), Barcelona, Spain.
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5
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Pinet K, McLaughlin KA. Mechanisms of physiological tissue remodeling in animals: Manipulating tissue, organ, and organism morphology. Dev Biol 2019; 451:134-145. [DOI: 10.1016/j.ydbio.2019.04.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 03/29/2019] [Accepted: 04/03/2019] [Indexed: 12/21/2022]
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Abstract
Sex determination and sexual development are highly diverse and controlled by mechanisms that are extremely labile. While dioecy (separate male and female functions) is the norm for most animals, hermaphroditism (both male and female functions within a single body) is phylogenetically widespread. Much of our current understanding of sexual development comes from a small number of model systems, limiting our ability to make broader conclusions about the evolution of sexual diversity. We present the calyptraeid gastropods as a model for the study of the evolution of sex determination in a sequentially hermaphroditic system. Calyptraeid gastropods, a group of sedentary, filter-feeding marine snails, are sequential hermaphrodites that change sex from male to female during their life span (protandry). This transition includes resorption of the penis and the elaboration of female genitalia, in addition to shifting from production of spermatocytes to oocytes. This transition is typically under environmental control and frequently mediated by social interactions. Males in contact with females delay sex change to transition at larger sizes, while isolated males transition more rapidly and at smaller sizes. This phenomenon has been known for over a century; however, the mechanisms that control the switch from male to female are poorly understood. We review here our current understanding of sexual development and sex determination in the calyptraeid gastropods and other molluscs, highlighting our current understanding of factors implicated in the timing of sex change and the potential mechanisms. We also consider the embryonic origins and earliest expression of the germ line and the effects of environmental contaminants on sexual development.
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7
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Henshaw JM, Jennions MD, Kruuk LEB. How to quantify (the response to) sexual selection on traits. Evolution 2018; 72:1904-1917. [PMID: 30004126 DOI: 10.1111/evo.13554] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 06/16/2018] [Accepted: 07/07/2018] [Indexed: 01/01/2023]
Abstract
Natural selection operates via fitness components like mating success, fecundity, and longevity, which can be understood as intermediaries in the causal process linking traits to fitness. In particular, sexual selection occurs when traits influence mating or fertilization success, which, in turn, influences fitness. We show how to quantify both these steps in a single path analysis, leading to better estimates of the strength of sexual selection. Our model controls for confounding variables, such as body size or condition, when estimating the relationship between mating and reproductive success. Correspondingly, we define the Bateman gradient and the Jones index using partial rather than simple regressions, which better captures how they are commonly interpreted. The model can be applied both to purely phenotypic data and to quantitative genetic parameters estimated using information on relatedness. The phenotypic approach breaks down selection differentials into a sexually selected and a "remainder" component. The quantitative genetic approach decomposes the estimated evolutionary response to selection analogously. We apply our method to analyze sexual selection in male dusky pipefish, Syngnathus floridae, and in two simulated datasets. We highlight conceptual and statistical limitations of previous path-based approaches, which can lead to substantial misestimation of sexual selection.
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Affiliation(s)
- Jonathan M Henshaw
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, ACT 2601, Canberra, Australia.,Institute of Zoology, University of Graz, Universitätsplatz 2, Graz, 8010, Austria
| | - Michael D Jennions
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, ACT 2601, Canberra, Australia
| | - Loeske E B Kruuk
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, ACT 2601, Canberra, Australia
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8
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Riquet F, Comtet T, Broquet T, Viard F. Unexpected collective larval dispersal but little support for sweepstakes reproductive success in the highly dispersive brooding molluscCrepidula fornicata. Mol Ecol 2017; 26:5467-5483. [DOI: 10.1111/mec.14328] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/27/2017] [Accepted: 08/07/2017] [Indexed: 01/16/2023]
Affiliation(s)
- Florentine Riquet
- UPMC Univ Paris 06; UMR 7144; Team Diversity and Connectivity in Coastal Marine Landscapes; Station Biologique de Roscoff; Roscoff France
- CNRS; UMR 7144; Lab. Adaptation and Diversity in the Marine Environment; Station Biologique de Roscoff; Roscoff France
| | - Thierry Comtet
- UPMC Univ Paris 06; UMR 7144; Team Diversity and Connectivity in Coastal Marine Landscapes; Station Biologique de Roscoff; Roscoff France
- CNRS; UMR 7144; Lab. Adaptation and Diversity in the Marine Environment; Station Biologique de Roscoff; Roscoff France
| | - Thomas Broquet
- UPMC Univ Paris 06; UMR 7144; Team Diversity and Connectivity in Coastal Marine Landscapes; Station Biologique de Roscoff; Roscoff France
- CNRS; UMR 7144; Lab. Adaptation and Diversity in the Marine Environment; Station Biologique de Roscoff; Roscoff France
| | - Frédérique Viard
- UPMC Univ Paris 06; UMR 7144; Team Diversity and Connectivity in Coastal Marine Landscapes; Station Biologique de Roscoff; Roscoff France
- CNRS; UMR 7144; Lab. Adaptation and Diversity in the Marine Environment; Station Biologique de Roscoff; Roscoff France
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9
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Koene JM. Sex determination and gender expression: Reproductive investment in snails. Mol Reprod Dev 2017; 84:132-143. [PMID: 27245260 PMCID: PMC6220956 DOI: 10.1002/mrd.22662] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/22/2016] [Indexed: 02/01/2023]
Abstract
Sex determination is generally seen as an issue of importance for separate-sexed organisms; however, when considering other sexual systems, such as hermaphroditism, sex allocation is a less-binary form of sex determination. As illustrated here, with examples from molluscs, this different vantage point can offer important evolutionary insights. After all, males and females produce only one type of gamete, whereas hermaphrodites produce both. In addition, sperm and accessory gland products are donated bidirectionally. For reciprocal mating, this is obvious since sperm are exchanged within one mating interaction; but even unilaterally mating species end up mating in both sexual roles, albeit not simultaneously. With this in mind, I highlight two factors that play an important role in how reproductive investment is divided in snails: First, the individual's motivation to preferentially donate rather than receive sperm (or vice versa) leads to flexible behavioral performance, and thereby investment, of either sex. Second, due to the presence of both sexual roles within the same individual, partners are potentially able to influence investment in both sexual functions of their partner to their own benefit. The latter has already led to novel insights into how accessory gland products may evolve. Moreover, the current evidence points towards different ways in which allocation to reproduction can be changed in simultaneous hermaphrodites. These often differ from the separate-sexed situation, highlighting that comparison across different sexual systems may help identify commonalities and differences in physiological, and molecular mechanisms as well as evolutionary patterns. Mol. Reprod. Dev. 84: 132-143, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Joris M. Koene
- Faculty of Earth and Life SciencesDepartment of Ecological ScienceVrije UniversiteitAmsterdamThe Netherlands
- Terrestrial ZoologyNaturalis Biodiversity CentreLeidenThe Netherlands
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10
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Eldon B, Riquet F, Yearsley J, Jollivet D, Broquet T. Current hypotheses to explain genetic chaos under the sea. Curr Zool 2016; 62:551-566. [PMID: 29491945 PMCID: PMC5829445 DOI: 10.1093/cz/zow094] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 08/27/2016] [Indexed: 01/07/2023] Open
Abstract
Chaotic genetic patchiness (CGP) refers to surprising patterns of spatial and temporal genetic structure observed in some marine species at a scale where genetic variation should be efficiently homogenized by gene flow via larval dispersal. Here we review and discuss 4 mechanisms that could generate such unexpected patterns: selection, sweepstakes reproductive success, collective dispersal, and temporal shifts in local population dynamics. First, we review examples where genetic differentiation at specific loci was driven by diversifying selection, which was historically the first process invoked to explain CGP. Second, we turn to neutral demographic processes that may drive genome-wide effects, and whose effects on CGP may be enhanced when they act together. We discuss how sweepstakes reproductive success accelerates genetic drift and can thus generate genetic structure, provided that gene flow is not too strong. Collective dispersal is another mechanism whereby genetic structure can be maintained regardless of dispersal intensity, because it may prevent larval cohorts from becoming entirely mixed. Theoretical analyses of both the sweepstakes and the collective dispersal ideas are presented. Finally, we discuss an idea that has received less attention than the other ones just mentioned, namely temporal shifts in local population dynamics.
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Affiliation(s)
- Bjarki Eldon
- Museum für Naturkunde Berlin, Leibniz Institut für Evolutions- und
Biodiversitätsforschung, Berlin 10115, Germany
| | - Florentine Riquet
- Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier Cedex 5,
France
- ISEM - CNRS, UMR 5554, SMEL, 2 rue des Chantiers, Sète 34200, France
| | - Jon Yearsley
- School of Biology and Environmental Science and UCD Earth Institute,
University College Dublin, Belfield, Dublin 4, Ireland
| | - Didier Jollivet
- Centre National de la Recherche Scientifique, Team Adaptation and Biology of
Invertebrates in Extreme Environments, Station Biologique de Roscoff, Roscoff 29680,
France
- Sorbonne Universités, Université Pierre et Marie Curie, Unité Mixte de
Recherche 7144, Station Biologique de Roscoff, Roscoff 29680, France
| | - Thomas Broquet
- Sorbonne Universités, Université Pierre et Marie Curie, Unité Mixte de
Recherche 7144, Station Biologique de Roscoff, Roscoff 29680, France
- Centre National de la Recherche Scientifique, Team Diversity and
Connectivity of Coastal Marine Landscapes, Station Biologique de Roscoff, Roscoff 29680,
France
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11
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Viard F, David P, Darling JA. Marine invasions enter the genomic era: three lessons from the past, and the way forward. Curr Zool 2016; 62:629-642. [PMID: 29491950 PMCID: PMC5804250 DOI: 10.1093/cz/zow053] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/15/2016] [Indexed: 01/22/2023] Open
Abstract
The expanding scale and increasing rate of marine biological invasions have been documented since the early 20th century. Besides their global ecological and economic impacts, non-indigenous species (NIS) also have attracted much attention as opportunities to explore important eco-evolutionary processes such as rapid adaptation, long-distance dispersal and range expansion, and secondary contacts between divergent evolutionary lineages. In this context, genetic tools have been extensively used in the past 20 years. Three important issues appear to have emerged from such studies. First, the study of NIS has revealed unexpected cryptic diversity in what had previously been assumed homogeneous entities. Second, there has been surprisingly little evidence of strong founder events accompanying marine introductions, a pattern possibly driven by large propagule loads. Third, the evolutionary processes leading to successful invasion have been difficult to ascertain due to faint genetic signals. Here we explore the potential of novel tools associated with high-throughput sequencing (HTS) to address these still pressing issues. Dramatic increase in the number of loci accessible via HTS has the potential to radically increase the power of analyses aimed at species delineation, exploring the population genomic consequences of range expansions, and examining evolutionary processes such as admixture, introgression, and adaptation. Nevertheless, the value of this new wealth of genomic data will ultimately depend on the ability to couple it with expanded "traditional" efforts, including exhaustive sampling of marine populations over large geographic scales, integrated taxonomic analyses, and population level exploration of quantitative trait differentiation through common-garden and other laboratory experiments.
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Affiliation(s)
- Frédérique Viard
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 7144, Lab. Adaptation Et Diversité En Milieu Marin, Team Div&Co, Station Biologique De Roscoff, Roscoff 29682, France
| | - Patrice David
- CEFE UMR 5175, CNRS-Université De Montpellier-UM III-EPHE, 1919 Route De Mende, Montpellier Cedex 34293, France
| | - John A. Darling
- National Exposure Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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12
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Brante A, Quiñones A, Silva F. The relationship between sex change and reproductive success in a protandric marine gastropod. Sci Rep 2016; 6:29439. [PMID: 27385040 PMCID: PMC4935951 DOI: 10.1038/srep29439] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 06/17/2016] [Indexed: 11/09/2022] Open
Abstract
Protandric species switch sex during their lifetime. According to theory, the time (body size) at which sex change occurs is determined by the reproductive success of individuals affected by social interactions as well as by post-copulatory factors. Experimental evidence is biased to few social systems making the exploration of general patterns difficult. We used the protandric marine gastropod Crepidula coquimbensis that partakes in intrabrood sibling cannibalism to test the following hypotheses: 1. Male-male competition for access to females and sibling cannibalism determine male reproductive success; 2. Males with greater access to females and with higher reproductive success will have reduced growth rates and will delay sex change. Artificial aggregations with different social structures were constructed and male reproductive success was estimated by paternity analysis. The results supported our expectations showing that male competitive ability for access to the female, time spent by males in the copulatory position, and sibling cannibalism affect reproductive success and influence time to sex change, with less successful males hastening sex change. Also, males that spent more time in the copulatory position had reduced growth rates. Comparing these results with those reported for other sequential hermaphrodites provides evidence supporting general patterns of sex change in nature.
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Affiliation(s)
- Antonio Brante
- Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Chile.,Centro de Investigación en Biodiversidad y Ambientes Sustentables (CIBAS), Universidad Católica de la Santísima Concepción. Casilla 297, Concepción, Chile
| | - Adriana Quiñones
- Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Chile
| | - Francisco Silva
- Departamento de Ecología, Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Chile
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13
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Riquet F, Le Cam S, Fonteneau E, Viard F. Moderate genetic drift is driven by extreme recruitment events in the invasive mollusk Crepidula fornicata. Heredity (Edinb) 2016; 117:42-50. [PMID: 27118155 PMCID: PMC4901356 DOI: 10.1038/hdy.2016.24] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 03/07/2016] [Accepted: 03/11/2016] [Indexed: 11/09/2022] Open
Abstract
Effective population size (Ne) is a measure of genetic drift and is thus a central parameter in evolution, conservation genetics and invasion biology. Interestingly, in native marine species, Ne is typically several orders of magnitude lower than the census size. This pattern has often been explained by high fecundity, variation in reproductive success and pronounced early mortality, resulting in genetic drift across generations. Data documenting genetic drift and/or Ne in marine invasive species are, however, still scarce. We examined the importance of genetic drift in the invasive species Crepidula fornicata by genotyping 681 juveniles sampled during each annual recruitment peak over nine consecutive years in the Bay of Morlaix (Brittany, France). Observed variations in genetic diversity were partially explained by variation in recruitment intensity. In addition, substantial temporal genetic differentiation was documented (that is, genetic drift), and was attributed to nonrandom variance in the reproductive success of different breeding groups across years in the study species. Using a set of single-sample and temporal estimators for Ne, we estimated Ne to be three or four orders of magnitude smaller than the census size (Nc). On one hand, this reduction in Ne relative to Nc appeared congruent with, although slight higher than, values commonly observed in native marine species. Particular life-history traits of this invasive species may play an important role in buffering genetic drift. On the other hand, Ne still remained far below Nc, hence, possibly reducing the efficiency of selection effects.
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Affiliation(s)
- F Riquet
- UPMC Univ Paris 06, UMR 7144, Team Diversity and Connectivity in Coastal Marine Landscapes, Station Biologique de Roscoff, Roscoff, France
- CNRS, UMR 7144, Laboratory Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Roscoff, France
| | - S Le Cam
- UPMC Univ Paris 06, UMR 7144, Team Diversity and Connectivity in Coastal Marine Landscapes, Station Biologique de Roscoff, Roscoff, France
- CNRS, UMR 7144, Laboratory Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Roscoff, France
| | - E Fonteneau
- UPMC Univ Paris 06, UMR 7144, Team Diversity and Connectivity in Coastal Marine Landscapes, Station Biologique de Roscoff, Roscoff, France
- CNRS, UMR 7144, Laboratory Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Roscoff, France
| | - F Viard
- UPMC Univ Paris 06, UMR 7144, Team Diversity and Connectivity in Coastal Marine Landscapes, Station Biologique de Roscoff, Roscoff, France
- CNRS, UMR 7144, Laboratory Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, Roscoff, France
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14
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Cahill AE, Juman AR, Pellman-Isaacs A, Bruno WT. Physical and Chemical Interactions with Conspecifics Mediate Sex Change in a Protandrous Gastropod Crepidula fornicata. THE BIOLOGICAL BULLETIN 2015; 229:276-281. [PMID: 26695826 DOI: 10.1086/bblv229n3p276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The protandrous marine snail Crepidula fornicata has been a theoretical and empirical model for studies of sex change for many decades. We investigated the social conditions under which sex change occurs in this species by manipulating physical and chemical contact with conspecifics. Male snails were either in physical and chemical contact with females or in chemical contact with, but physically isolated from, females. Males were tested both with living females and with empty, sterilized shells. Males that were physically touching a living female were less likely to change sex than the isolated controls, while males in chemical (but not physical) contact with females changed sex no slower than the isolated controls. These results provide experimental evidence that the factor controlling sex change in C. fornicata is due to a contact-borne inhibitor associated with female conspecifics. These findings serve as a basis for future studies of sex change in this model system.
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Affiliation(s)
- Abigail E Cahill
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York 11794-5245
| | - Alia Rehana Juman
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York 11794-5245
| | - Aaron Pellman-Isaacs
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York 11794-5245
| | - William T Bruno
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York 11794-5245
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