1
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Hou M, Opedal ØH, Zhao ZG. Sexually concordant selection on floral traits despite greater opportunity for selection through male fitness. THE NEW PHYTOLOGIST 2024; 241:926-936. [PMID: 37899633 DOI: 10.1111/nph.19370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/16/2023] [Indexed: 10/31/2023]
Abstract
Pollinators are important drivers of floral trait evolution, yet plant populations are not always perfectly adapted to their pollinators. Such apparent maladaptation may result from conflicting selection through male and female sexual functions in hermaphrodites. We studied sex-specific mating patterns and phenotypic selection on floral traits in Aconitum gymnandrum. After genotyping 1786 offspring, we partitioned individual fitness into sex-specific selfed and outcrossed components and estimated phenotypic selection acting through each. Relative fitness increased with increasing mate number, and more so for male function. This led to greater opportunity for selection through outcrossed male fitness, though patterns of phenotypic selection on floral traits tended to be similar, and with better support for selection through female rather than male fitness components. We detected directional selection through one or more fitness component for larger flower number, larger flowers, and more negative nectar gradients within inflorescences. Our results are consistent with Bateman's principles for sex-specific mating patterns and illustrate that, despite the expected difference in opportunity for selection, patterns of variation in selection across traits can be rather similar for the male and female sexual functions. These results shed new light on the effect of sexual selection on the evolution of floral traits.
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Affiliation(s)
- Meng Hou
- College of Ecology, Lanzhou University, 730000, Lanzhou, China
- Key Laboratory of Wetland Ecology and Environment, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, 130102, Changchun, China
| | | | - Zhi-Gang Zhao
- College of Ecology, Lanzhou University, 730000, Lanzhou, China
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2
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Kwok A, Dorken ME. Sexual selection on male but not female function in monoecious and dioecious populations of broadleaf arrowhead ( Sagittaria latifolia). Proc Biol Sci 2022; 289:20220919. [PMID: 36350202 PMCID: PMC9653219 DOI: 10.1098/rspb.2022.0919] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 10/12/2022] [Indexed: 09/30/2023] Open
Abstract
Direct measures of sexual selection in plants are rare and complicated by immobility and modular growth. For plants, instantaneous measures of fitness typically scale with size, but covariances between size and mating success could obscure the detection of sexual selection. We measured the magnitude of sexual selection in a monoecious and a dioecious population of the clonal plant Sagittaria latifolia using Bateman gradients (ßss). These gradients were calculated using parentage analysis and residual regression to account for the effects of shoot and clone size on mating and reproductive success. In both populations, (i) there was greater promiscuity via male function than via female function and (ii) ßss were positive, with significant associations between mating and reproductive success for male but not female function. Moreover, estimated βss were similar for the monoecious and dioecious populations, possibly because non-overlapping female and male sex phases in hermaphroditic S. latifolia reduced the scope for interference between sex functions during mating. This study builds on previous studies of selection on plant mating traits, and of sexual selection under experimental conditions, by showing that sexual selection can operate in natural populations of plants, including populations of hermaphrodites.
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Affiliation(s)
- Allison Kwok
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada K9J 0G2
| | - Marcel E. Dorken
- Department of Biology, Trent University, Peterborough, ON, Canada K9J 0G2
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3
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Simón‐Porcar VI, Muñoz‐Pajares AJ, de Castro A, Arroyo J. Direct evidence supporting Darwin's hypothesis of cross-pollination promoted by sex organ reciprocity. THE NEW PHYTOLOGIST 2022; 235:2099-2110. [PMID: 35596603 PMCID: PMC9546006 DOI: 10.1111/nph.18266] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 05/09/2022] [Indexed: 05/28/2023]
Abstract
The floral phenotype plays a main role in the attraction and fit of pollinators. Both perianth traits and the positioning of sex organs can be subjected to natural selection and determine nonrandom mating patterns in populations. In stylar-polymorphic species, the Darwinian hypothesis predicts increased mating success between individuals with sex organs at equivalent heights (i.e. with higher reciprocity). We used paternity analyses in experimental populations of a stylar-dimorphic species. By comparing the observed mating patterns with those expected under random mating, we tested the effects of sex organ reciprocity and perianth traits on mating success. We also analysed phenotypic selection on perianth traits through female and male functions. The (dis)similarity of parental perianth traits had no direct effects on the mating patterns. Sex organ reciprocity had a positive effect on mating success. Narrow floral tubes increased this effect in upper sex organs. Perianth traits showed little signs of phenotypic selection. Female and absolute fitness measures resulted in different patterns of phenotypic selection. We provide precise empirical evidence of the Darwinian hypothesis about the functioning of stylar polymorphisms, demonstrating that mating patterns are determined by sex organ reciprocity and only those perianth traits which are critical to pollinator fit.
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Affiliation(s)
| | - A. Jesús Muñoz‐Pajares
- Department of GeneticsUniversity of GranadaE‐18071GranadaSpain
- Research Centre in Biodiversity and Genetic Resources (CIBIO)Campus Agrário de Vairão4485‐661VairãoPortugal
| | - Alejandra de Castro
- Department of Plant Biology and EcologyUniversity of SevilleE‐41080SevilleSpain
| | - Juan Arroyo
- Department of Plant Biology and EcologyUniversity of SevilleE‐41080SevilleSpain
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4
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Brand JN, Harmon LJ, Schärer L. Frequent origins of traumatic insemination involve convergent shifts in sperm and genital morphology. Evol Lett 2022; 6:63-82. [PMID: 35127138 PMCID: PMC8802240 DOI: 10.1002/evl3.268] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 12/18/2022] Open
Abstract
Traumatic insemination is a mating behavior during which the (sperm) donor uses a traumatic intromittent organ to inject an ejaculate through the epidermis of the (sperm) recipient, thereby frequently circumventing the female genitalia. Traumatic insemination occurs widely across animals, but the frequency of its evolution, the intermediate stages via which it originates, and the morphological changes that such shifts involve remain poorly understood. Based on observations in 145 species of the free-living flatworm genus Macrostomum, we identify at least nine independent evolutionary origins of traumatic insemination from reciprocal copulation, but no clear indication of reversals. These origins involve convergent shifts in multivariate morphospace of male and female reproductive traits, suggesting that traumatic insemination has a canalizing effect on morphology. We also observed sperm in both the sperm receiving organ and within the body tissue of two species. These species had intermediate trait values indicating that traumatic insemination evolves through initial internal wounding during copulation. Finally, signatures of male-female coevolution of genitalia across the genus indicate that sexual selection and sexual conflict drive the evolution of traumatic insemination, because it allows donors to bypass postcopulatory control mechanisms of recipients.
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Affiliation(s)
- Jeremias N. Brand
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBaselCH‐4051Switzerland
- Department of Tissue Dynamics and RegenerationMax Planck Institute for Biophysical ChemistryGöttingenDE‐37077Germany
| | - Luke J. Harmon
- Department of Biological SciencesUniversity of IdahoMoscowIdaho83843
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBaselCH‐4051Switzerland
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5
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Resende RS, Cardoso SJ, D'ávila S. Responses of Leptinaria unilamellata (Gastropoda: Subulinidae) to Novel Micro-Environmental Conditions: Shift in Shell Morphology and the Balance between Protection against Desiccation and Reproductive Success. Zoolog Sci 2020; 37:148-158. [PMID: 32282146 DOI: 10.2108/zs180201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 11/12/2019] [Indexed: 11/17/2022]
Abstract
In the present study, we observed that Leptinaria unilamellata responds to changes in microclimatic conditions through shifts in shell morphology. Over three laboratory generations, shell differences between two populations, representing distinct morphotypes, became less evident. Only F1 generations from both populations showed shell morphometry very similar to the field parental snails, suggesting maternal effect. Snails from the locality with higher values of rainfall, relative humidity and evaporation index and smaller values of temperature and insolation produced more and larger hatchlings. Snails from the locality with less favorable climatic conditions presented shells traits that offer protection against desiccation, but reduce reproductive success. These snails showed smaller offspring production and faster response to a desiccation regime, through changes in conchiometrics. In addition, the results of the present study suggest that the spire index plays a less important role in determining protective properties of the shell of L. unilamellata, in response to desiccation risk, compared to aperture dimension. As shell aperture dimension is an important trait related to resistance to desiccation, and at the same time to reproduction, plastic responses to environmental conditions promoting the balance between survival and reproductive success are critical for the species adaptive success.
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Affiliation(s)
- Raquel Seixas Resende
- Museu de Malacologia Prof. Maury Pinto de Oliveira, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, S/n - Martelos, Juiz de Fora, 36036-330 Minas Gerais, Brazil
| | - Simone Jaqueline Cardoso
- Laboratório de Ecologia Aquática, Universidade Federal de Juiz de Fora, 36036-330 Minas Gerais, Brazil.,Departamento de Zoologia, Universidade Federal de Juiz de Fora, 36036-330 Minas Gerais, Brazil
| | - Sthefane D'ávila
- Museu de Malacologia Prof. Maury Pinto de Oliveira, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, S/n - Martelos, Juiz de Fora, 36036-330 Minas Gerais, Brazil, .,Departamento de Zoologia, Universidade Federal de Juiz de Fora, 36036-330 Minas Gerais, Brazil,
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6
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Daupagne L, Koene JM. Disentangling female postmating responses induced by semen transfer components in a simultaneous hermaphrodite. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Felmy A, Weissert N, Travis J, Jokela J. Mate availability determines use of alternative reproductive phenotypes in hermaphrodites. Behav Ecol 2020. [DOI: 10.1093/beheco/araa046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
In many species, individuals can employ alternative reproductive phenotypes, with profound consequences for individual fitness and population dynamics. This is particularly relevant for self-compatible hermaphrodites, which have exceptionally many reproductive options. Here we investigated the occurrence of reproductive phenotypes in the simultaneously hermaphroditic freshwater snail Radix balthica under experimentally simulated conditions of low versus moderate population density. We captured all mating behavior on camera and measured individual female lifetime reproductive success. We found every possible reproductive phenotype: (1) both male and female (i.e., truly hermaphroditic) reproduction, (2) purely female and (3) purely male reproduction, (4) male reproduction combined with self-fertilization and (5) female mating activity, (6) pure self-fertilization without mating and (7–8) two types of reproductive failure. Variation in alternative reproductive phenotypes was explained by mate availability (10.8%) and individual condition, approximated by a snail’s mean daily growth rate (17.5%). Increased mate availability resulted in a lower diversity of reproductive phenotypes, in particular increasing the frequency of true hermaphrodites. However, it lowered phenotype-specific fecundities and hence reduced the population growth rate. Snails in better condition were more likely to reproduce as true hermaphrodites or pure females, whereas low-condition snails tended to suffer reproductive failure. Overall, we show substantial variation in alternative reproductive phenotypes in a hermaphrodite, which is possibly in part maintained by fluctuations in population density and thus mate availability, and by variation in individual condition. We also provide evidence of an almost 2-fold increase in clutch size that can be ascribed specifically to mating as a female.
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Affiliation(s)
- Anja Felmy
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf, Switzerland
- ETH Zurich, D-USYS, Institute of Integrative Biology, Universitätstrasse 16, Zurich, Switzerland
- Department of Zoology, University of Oxford, Oxford, UK
| | - Nora Weissert
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf, Switzerland
| | - Joseph Travis
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Jukka Jokela
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, Dübendorf, Switzerland
- ETH Zurich, D-USYS, Institute of Integrative Biology, Universitätstrasse 16, Zurich, Switzerland
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8
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Fodor I, Hussein AAA, Benjamin PR, Koene JM, Pirger Z. The unlimited potential of the great pond snail, Lymnaea stagnalis. eLife 2020; 9:e56962. [PMID: 32539932 PMCID: PMC7297532 DOI: 10.7554/elife.56962] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 05/27/2020] [Indexed: 12/14/2022] Open
Abstract
Only a limited number of animal species lend themselves to becoming model organisms in multiple biological disciplines: one of these is the great pond snail, Lymnaea stagnalis. Extensively used since the 1970s to study fundamental mechanisms in neurobiology, the value of this freshwater snail has been also recognised in fields as diverse as host-parasite interactions, ecotoxicology, evolution, genome editing and 'omics', and human disease modelling. While there is knowledge about the natural history of this species, what is currently lacking is an integration of findings from the laboratory and the field. With this in mind, this article aims to summarise the applicability of L. stagnalis and points out that this multipurpose model organism is an excellent, contemporary choice for addressing a large range of different biological questions, problems and phenomena.
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Affiliation(s)
- István Fodor
- NAP Adaptive Neuroethology, Department of Experimental Zoology, Balaton Limnological Institute, Centre for Ecological ResearchTihanyHungary
| | - Ahmed AA Hussein
- Department of Ecological Sciences, Faculty of Sciences, Vrije UniversiteitAmsterdamNetherlands
| | - Paul R Benjamin
- Sussex Neuroscience, School of Life Sciences, University of SussexBrightonUnited Kingdom
| | - Joris M Koene
- Section of Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit AmsterdamAmsterdamNetherlands
| | - Zsolt Pirger
- NAP Adaptive Neuroethology, Department of Experimental Zoology, Balaton Limnological Institute, Centre for Ecological ResearchTihanyHungary
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9
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Kaufmann P, Schärer L. Is the initiation of selfing linked to a hermaphrodite's female or male reproductive function? Behav Ecol Sociobiol 2020; 74:41. [PMID: 32214615 PMCID: PMC7080307 DOI: 10.1007/s00265-020-2816-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 02/11/2020] [Accepted: 02/24/2020] [Indexed: 11/30/2022]
Abstract
ABSTRACT There is an ongoing debate about whether simultaneous hermaphrodites capable of selfing should prefer selfing over outcrossing or vice versa. While many theoretical models predict a transmission advantage for alleles that favour selfing, empirical studies often reveal low selfing rates. Despite these considerations, the underlying mechanisms that determine reproductive strategies in simultaneously hermaphroditic animals are poorly understood. In our study on the facultatively selfing free-living flatworm, Macrostomum hystrix, we ask whether the initiation of selfing, as inferred from the differential spatial distribution of received sperm, is linked to an individual's female or male reproductive function. Specifically, the initiation of selfing could (i) be linked to the male function, when an individual is unable to donate sperm to others and hence donates sperm to self, or it could (ii) be linked to the female function, when an individual fails to receive sperm from others-and hence is unable to fertilize its eggs via outcrossing-thus inducing it to self-fertilize. We experimentally created a social environment that allowed focals to outcross via sperm donation, but simultaneously prevented them from receiving sperm-by pairing them with a partner lacking the male copulatory organ-so that fertilization of the focal's eggs was restricted to selfing. Our results suggest that such focals generally do not initiate selfing, while we readily observe selfing in isolated worms. This suggests that in isolated M. hystrix, it is the male function that is linked to the initiation of selfing, likely due to a lack of opportunities for sperm donation. SIGNIFICANCE STATEMENT A variety of simultaneously hermaphroditic animals are capable of reproducing via both selfing and outcrossing. While the reproductive choices of such animals can be modelled by the joint action of genetic (e.g. inbreeding depression) and ecological factors (e.g. partner availability), experimental evaluation of theoretical results is often lacking. By manipulating the social environment of focal individuals, we here provide evidence that explores the respective role that the co-occurring male and female sex functions have on the initiation of selfing in a simultaneously hermaphroditic flatworm species. Specifically, our results suggest that the initiation of selfing is linked to the worm's male function. Insights about which function is linked to the initiation of selfing may ultimately help to better understand reproductive decisions in simultaneous hermaphrodites.
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Affiliation(s)
- Philipp Kaufmann
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
- Present Address: Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
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10
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Nakadera Y, Giannakara A, Ramm SA. Plastic expression of seminal fluid protein genes in a simultaneously hermaphroditic snail. Behav Ecol 2019. [DOI: 10.1093/beheco/arz027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Yumi Nakadera
- Evolutionary Biology Department, Bielefeld University, Germany Morgenbreede 45, 33615 Bielefeld, Germany
| | - Athina Giannakara
- Evolutionary Biology Department, Bielefeld University, Germany Morgenbreede 45, 33615 Bielefeld, Germany
| | - Steven A Ramm
- Evolutionary Biology Department, Bielefeld University, Germany Morgenbreede 45, 33615 Bielefeld, Germany
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11
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Noël E, Fruitet E, Lelaurin D, Bonel N, Ségard A, Sarda V, Jarne P, David P. Sexual selection and inbreeding: Two efficient ways to limit the accumulation of deleterious mutations. Evol Lett 2018; 3:80-92. [PMID: 30788144 PMCID: PMC6369961 DOI: 10.1002/evl3.93] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 11/14/2018] [Indexed: 12/12/2022] Open
Abstract
Theory and empirical data showed that two processes can boost selection against deleterious mutations, thus facilitating the purging of the mutation load: inbreeding, by exposing recessive deleterious alleles to selection in homozygous form, and sexual selection, by enhancing the relative reproductive success of males with small mutation loads. These processes tend to be mutually exclusive because sexual selection is reduced under mating systems that promote inbreeding, such as self‐fertilization in hermaphrodites. We estimated the relative efficiency of inbreeding and sexual selection at purging the genetic load, using 50 generations of experimental evolution, in a hermaphroditic snail (Physa acuta). To this end, we generated lines that were exposed to various intensities of inbreeding, sexual selection (on the male function), and nonsexual selection (on the female function). We measured how these regimes affected the mutation load, quantified through the survival of outcrossed and selfed juveniles. We found that juvenile survival strongly decreased in outbred lines with reduced male selection, but not when female selection was relaxed, showing that male‐specific sexual selection does purge deleterious mutations. However, in lines exposed to inbreeding, where sexual selection was also relaxed, survival did not decrease, and even increased for self‐fertilized juveniles, showing that purging through inbreeding can compensate for the absence of sexual selection. Our results point to the further question of whether a mixed strategy combining the advantages of both mechanisms of genetic purging could be evolutionary stable.
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Affiliation(s)
- Elsa Noël
- UMR AGAP (CIRAD-INRA-Montpellier SupAgro) 2 Place Pierre Viala 34060 Montpellier Cedex 1 France.,Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Elise Fruitet
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France.,Department of Entomology Max Planck Institute for Chemical Ecology, Hans Knöll Strasse 8 Jena 07745 Germany.,IBED University of Amsterdam Science Park 904, 1098 XH Amsterdam The Netherlands
| | - Dennyss Lelaurin
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Nicolas Bonel
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France.,Universidad Nacional del Sur B8000ICN Bahía Blanca Argentina
| | - Adeline Ségard
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Violette Sarda
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Philippe Jarne
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
| | - Patrice David
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS-Université de Montpellier-Université Paul Valéry Montpellier-IRD-EPHE 1919 route de Mende, 34293 Montpellier cedex 5 France
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12
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Hare RM, Simmons LW. Sexual selection and its evolutionary consequences in female animals. Biol Rev Camb Philos Soc 2018; 94:929-956. [DOI: 10.1111/brv.12484] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/31/2018] [Accepted: 11/02/2018] [Indexed: 01/01/2023]
Affiliation(s)
- Robin M. Hare
- Centre for Evolutionary Biology, School of Biological Sciences University of Western Australia 35 Stirling Highway, Perth, 6009 Australia
| | - Leigh W. Simmons
- Centre for Evolutionary Biology, School of Biological Sciences University of Western Australia 35 Stirling Highway, Perth, 6009 Australia
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13
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Picchi L, Cabanes G, Ricci-Bonot C, Lorenzi MC. Quantitative Matching of Clutch Size in Reciprocating Hermaphroditic Worms. Curr Biol 2018; 28:3254-3259.e3. [PMID: 30318354 DOI: 10.1016/j.cub.2018.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/04/2018] [Accepted: 08/02/2018] [Indexed: 10/28/2022]
Abstract
Reciprocity [1] is one of the most controversial evolutionary explanations of cooperation among non-kin [2, 3]. For some authors, cognitive capacity of non-human organisms is limiting, and more parsimonious mechanisms should apply [3-5]; for others, the debate is mainly semantic [2, 6], and empirical evidence can be found in a wide range of taxa [7]. However, while the ability to alternate cooperative behaviors does not settle the reciprocity controversy, the capacity to adjust cooperative behavior to the value of received help could prove decisive. Marine polychaete worms Ophryotrocha diadema, as several simultaneous hermaphrodites, do not self-fertilize and have unilateral mating (i.e., they behave either as females or as males during each mating event). They are also external fertilizers and thus cannot store allosperm, which contribute to make them ideal model organisms to investigate reciprocity, since partners usually alternate sexual roles with each other, repeatedly exchanging egg clutch of variable size [8-12]. However, whether the alternation of sexual roles is the result of conditional reciprocity rather than by-product reciprocity has never been tested [13]. Here, we show that O. diadema worms reciprocate eggs conditionally to the partner's behavior and adjust the quality of cooperation according to that of their partners. Moreover, only egg reciprocation offers similar fitness returns via both the female and the male function with respect to non-reciprocating laying strategies. These results document that fine-tuned forms of conditional reciprocity can emerge in cognitively unsophisticated animals, broadening the criteria to recognize conditional reciprocity among animals.
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Affiliation(s)
- Laura Picchi
- LEEC - Laboratoire d'Ethologie Expérimentale et Comparée, Université Paris 13, Sorbonne Paris Cité, 99 avenue J.-B. Clément, 93430 Villetaneuse, France.
| | - Guénaël Cabanes
- LIPN - Laboratoire d'Informatique de Paris-Nord, Université Paris 13, Sorbonne Paris Cité, 99 avenue J.-B. Clément, 93430 Villetaneuse, France
| | - Claire Ricci-Bonot
- LEEC - Laboratoire d'Ethologie Expérimentale et Comparée, Université Paris 13, Sorbonne Paris Cité, 99 avenue J.-B. Clément, 93430 Villetaneuse, France
| | - Maria Cristina Lorenzi
- LEEC - Laboratoire d'Ethologie Expérimentale et Comparée, Université Paris 13, Sorbonne Paris Cité, 99 avenue J.-B. Clément, 93430 Villetaneuse, France
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14
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Olito C, Abbott JK, Jordan CY. The interaction between sex-specific selection and local adaptation in species without separate sexes. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170426. [PMID: 30150224 PMCID: PMC6125720 DOI: 10.1098/rstb.2017.0426] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2018] [Indexed: 11/12/2022] Open
Abstract
Local adaptation in hermaphrodite species can be based on a variety of fitness components, including survival, as well as both female and male sex-functions within individuals. When selection via female and male fitness components varies spatially (e.g. due to environmental heterogeneity), local adaptation will depend, in part, on variation in selection through each fitness component, and the extent to which genetic trade-offs between sex-functions maintain genetic variation necessary for adaptation. Local adaptation will also depend on the hermaphrodite mating system because self-fertilization alters several key factors influencing selection and the maintenance of genetic variance underlying trade-offs between the sex-functions (sexually antagonistic polymorphism). As a first step to guide intuition regarding sex-specific adaptation in hermaphrodites, we develop a simple theoretical model incorporating the essential features of hermaphrodite mating and adaptation in a spatially heterogeneous environment, and explore the interaction between sex-specific selection, self-fertilization and local adaptation. Our results suggest that opportunities for sex-specific local adaptation in hermaphrodites depend strongly on the extent of self-fertilization and inbreeding depression. Using our model as a conceptual framework, we provide a broad overview of the literature on sex-specific selection and local adaptation in hermaphroditic plants and animals, emphasizing promising future directions in light of our theoretical predictions.This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.
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Affiliation(s)
- Colin Olito
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Victoria 3800, Australia
- Department of Biology, Section for Evolutionary Ecology, Lund University, Lund, Sweden
| | - Jessica K Abbott
- Department of Biology, Section for Evolutionary Ecology, Lund University, Lund, Sweden
| | - Crispin Y Jordan
- School of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
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15
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Bonel N, Noël E, Janicke T, Sartori K, Chapuis E, Ségard A, Meconcelli S, Pélissié B, Sarda V, David P. Asymmetric evolutionary responses to sex-specific selection in a hermaphrodite. Evolution 2018; 72:2181-2201. [PMID: 30109706 DOI: 10.1111/evo.13565] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 07/25/2018] [Indexed: 01/10/2023]
Abstract
Sex allocation theory predicts that simultaneous hermaphrodites evolve to an evolutionary stable resource allocation, whereby any increase in investment to male reproduction leads to a disproportionate cost on female reproduction and vice versa. However, empirical evidence for sexual trade-offs in hermaphroditic animals is still limited. Here, we tested how male and female reproductive traits evolved under conditions of reduced selection on either male or female reproduction for 40 generations in a hermaphroditic snail. This selection favors a reinvestment of resources from the sex function under relaxed selection toward the other function. We found no such evolutionary response. Instead, juvenile survival and male reproductive success significantly decreased in lines where selection on the male function (i.e., sexual selection) was relaxed, while relaxing selection on the female function had no effect. Our results suggest that most polymorphisms under selection in these lines were not sex-antagonistic. Rather, they were deleterious mutations affecting juvenile survival (thus reducing both male and female fitness) with strong pleiotropic effects on male success in a sexual selection context. These mutations accumulated when sexual selection was relaxed, which supports the idea that sexual selection in hermaphrodites contributes to purge the mutation load from the genome as in separate-sex organisms.
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Affiliation(s)
- Nicolás Bonel
- Laboratorio de Zoología de Invertebrados I, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, B8000ICN, Bahía Blanca, CONICET, Argentina.,Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
| | - Elsa Noël
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France.,Institute for Population Genetics, University of Veterinary Medicine, Veterinärplatz 1, A-1210, Vienna, Austria
| | - Tim Janicke
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France.,School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, United Kingdom
| | - Kevin Sartori
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
| | - Elodie Chapuis
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France.,IRD, UMR186 Intéractions Plantes-Microrganismes-Environement, 911, Avenue Agropolis, BP 64501 34394 Montpellier Cedex 05, France.,CIRAD, UMR PVBMT, F-97410 St Pierre, La Réunion, France
| | - Adeline Ségard
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
| | - Stefania Meconcelli
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France.,Department of Life Sciences and Systems Biology, Università di Torino, Turin, Italy
| | - Benjamin Pélissié
- University of Wisconsin Madison, Department of Entomology, 1630 Linden Dr, Madison, Wisconsin 53706
| | - Violette Sarda
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
| | - Patrice David
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Ecole Pratique des Hautes Etudes, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
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16
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Hoffer JN, Mariën J, Ellers J, Koene JM. Sexual selection gradients change over time in a simultaneous hermaphrodite. eLife 2017; 6. [PMID: 28613158 PMCID: PMC5511009 DOI: 10.7554/elife.25139] [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: 01/14/2017] [Accepted: 06/13/2017] [Indexed: 12/17/2022] Open
Abstract
Sexual selection is generally predicted to act more strongly on males than on females. The Darwin-Bateman paradigm predicts that this should also hold for hermaphrodites. However, measuring this strength of selection is less straightforward when both sexual functions are performed throughout the organism's lifetime. Besides, quantifications of sexual selection are usually done during a short time window, while many animals store sperm and are long-lived. To explore whether the chosen time frame affects estimated measures of sexual selection, we recorded mating success and reproductive success over time, using a simultaneous hermaphrodite. Our results show that male sexual selection gradients are consistently positive. However, an individual's female mating success seems to negatively affect its own male reproductive success, an effect that only becomes visible several weeks into the experiment, highlighting that the time frame is crucial for the quantification and interpretation of sexual selection measures, an insight that applies to any iteroparous mating system.
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Affiliation(s)
- Jeroen Na Hoffer
- Section of Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands
| | - Janine Mariën
- Section of Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands
| | - Jacintha Ellers
- Section of Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands
| | - Joris M Koene
- Section of Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit, Amsterdam, The Netherlands
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17
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Bürkli A, Jokela J. Increase in multiple paternity across the reproductive lifespan in a sperm-storing, hermaphroditic freshwater snail. Mol Ecol 2017; 26:5264-5278. [PMID: 28605149 DOI: 10.1111/mec.14200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 12/28/2022]
Abstract
Polyandry is a common phenomenon and challenges the traditional view of stronger sexual selection in males than in females. In simultaneous hermaphrodites, the physical proximity of both sex functions was long thought to preclude the operation of sexual selection. Laboratory studies suggest that multiple mating and polyandry in hermaphrodites may actually be common, but data from natural populations are sparse. We therefore estimated the rate of multiple paternity and its seasonal variability in the annual, sperm-storing, simultaneously hermaphroditic freshwater snail Radix balthica for the entire duration of the reproductive lifespan. We also tested whether multiple paternity was associated with clutch size or embryonic development. To obtain these data, we measured and genotyped 60 field-collected egg clutches using nine highly polymorphic microsatellite markers. Overall, 50% of the clutches had multiple fathers, and both the frequency (20-93% of clutches) and magnitude of multiple paternity (mean 1.3-3.8 fathers per clutch) substantially increased over time, probably because of extensive sperm storage. Most multiply sired clutches (83%) had a dominant father, but neither clutch size nor the proportion of developed embryos per clutch was associated with levels of multiple paternity. Both the evident promiscuity and the frequent skew of paternity shares suggest that sexual selection may be an important evolutionary force in the study population.
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Affiliation(s)
- Anja Bürkli
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.,ETH Zurich, D-USYS, Institute of Integrative Biology, Zürich, Switzerland
| | - Jukka Jokela
- Department of Aquatic Ecology, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland.,ETH Zurich, D-USYS, Institute of Integrative Biology, Zürich, Switzerland
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18
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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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19
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Anthes N, Häderer IK, Michiels NK, Janicke T. Measuring and interpreting sexual selection metrics: evaluation and guidelines. Methods Ecol Evol 2016. [DOI: 10.1111/2041-210x.12707] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Nils Anthes
- Animal Evolutionary Ecology Group Institute for Evolution and Ecology University of Tübingen Auf der Morgenstelle 28 72076 Tübingen Germany
| | - Ines K. Häderer
- Animal Evolutionary Ecology Group Institute for Evolution and Ecology University of Tübingen Auf der Morgenstelle 28 72076 Tübingen Germany
| | - Nico K. Michiels
- Animal Evolutionary Ecology Group Institute for Evolution and Ecology University of Tübingen Auf der Morgenstelle 28 72076 Tübingen Germany
| | - Tim Janicke
- Centre d'Écologie Fonctionnelle et Évolutive UMR 5175 CNRS University of Montpellier 1919 Route de Mende 34293 Montpellier Cedex 05 France
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20
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Dorken ME, Perry LE. Correlated paternity measures mate monopolization and scales with the magnitude of sexual selection. J Evol Biol 2016; 30:377-387. [DOI: 10.1111/jeb.13013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 11/03/2016] [Accepted: 11/09/2016] [Indexed: 01/03/2023]
Affiliation(s)
- M. E. Dorken
- Department of Biology; Trent University; Peterborough ON Canada
| | - L. E. Perry
- Department of Biology; Trent University; Peterborough ON Canada
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21
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Beekman M, Nieuwenhuis B, Ortiz-Barrientos D, Evans JP. Sexual selection in hermaphrodites, sperm and broadcast spawners, plants and fungi. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150541. [PMID: 27619704 PMCID: PMC5031625 DOI: 10.1098/rstb.2015.0541] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/23/2016] [Indexed: 11/12/2022] Open
Abstract
Darwin was the first to recognize that sexual selection is a strong evolutionary force. Exaggerated traits allow same-sex individuals to compete over access to mates and provide a mechanism by which mates are selected. It is relatively easy to appreciate how inter- and intrasexual selection work in organisms with the sensory capabilities to perceive physical or behavioural traits that signal mate quality or mate compatibility, and to assess the relative quality of competitors. It is therefore not surprising that most studies of sexual selection have focused on animals with separate sexes and obvious adaptations that function in the context of reproductive competition. Yet, many sexual organisms are both male and female at the same time, often lack sexual dimorphism and never come into direct contact at mating. How does sexual selection act in such species, and what can we learn from them? Here, we address these questions by exploring the potential for sexual selection in simultaneous hermaphrodites, sperm- and broadcast spawners, plants and fungi. Our review reveals a range of mechanisms of sexual selection, operating primarily after gametes have been released, which are common in many of these groups and also quite possibly in more familiar (internally fertilizing and sexually dimorphic) organisms.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Madeleine Beekman
- School of Life and Environmental Sciences, University of Sydney, 2006 New South Wales, Australia
| | - Bart Nieuwenhuis
- Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
| | | | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, 6009 Western Australia, Australia
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22
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Courtiol A, Etienne L, Feron R, Godelle B, Rousset F. The Evolution of Mutual Mate Choice under Direct Benefits. Am Nat 2016; 188:521-538. [PMID: 27788341 DOI: 10.1086/688658] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
In nature, the intensity of mate choice (i.e., choosiness) is highly variable within and between sexes. Despite growing empirical evidence of male and/or mutual mate choice, theoretical investigations of the joint evolution of female and male choosiness are few. In addition, previous approaches have often assumed an absence of trade-off between the direct benefits per mating and the lower mating rate that results from being choosy. Here we model the joint evolution of female and male choosiness when it is solely ruled by this fundamental trade-off. We show that this trade-off can generate a diversity of stable combinations of choosiness. Mutual mate choice can evolve only if both females and males exhibit long latency after mating. Furthermore, we show that an increase in choosiness in one sex does not necessarily prevent the evolution of mutual mate choice; the outcome depends on details shaping the trade-off: the life history, the decision rule for mate choice, and how the fecundity of a pair is shaped by the quality of both individuals. Last, we discuss the power of the sensitivity of the relative searching time (i.e., of the proportion of a lifetime spent searching for mates) as a predictor of the joint evolution of choosiness.
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23
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Johnson MG, Shaw AJ. The effects of quantitative fecundity in the haploid stage on reproductive success and diploid fitness in the aquatic peat moss Sphagnum macrophyllum. Heredity (Edinb) 2016; 116:523-30. [PMID: 26905464 DOI: 10.1038/hdy.2016.13] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 11/23/2015] [Accepted: 12/29/2015] [Indexed: 11/09/2022] Open
Abstract
A major question in evolutionary biology is how mating patterns affect the fitness of offspring. However, in animals and seed plants it is virtually impossible to investigate the effects of specific gamete genotypes. In bryophytes, haploid gametophytes grow via clonal propagation and produce millions of genetically identical gametes throughout a population. The main goal of this research was to test whether gamete identity has an effect on the fitness of their diploid offspring in a population of the aquatic peat moss Sphagnum macrophyllum. We observed a heavily male-biased sex ratio in gametophyte plants (ramets) and in multilocus microsatellite genotypes (genets). There was a steeper relationship between mating success (number of different haploid mates) and fecundity (number of diploid offspring) for male genets compared with female genets. At the sporophyte level, we observed a weak effect of inbreeding on offspring fitness, but no effect of brood size (number of sporophytes per maternal ramet). Instead, the identities of the haploid male and haploid female parents were significant contributors to variance in fitness of sporophyte offspring in the population. Our results suggest that intrasexual gametophyte/gamete competition may play a role in determining mating success in this population.
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Affiliation(s)
- M G Johnson
- Department of Biology, Duke University, Durham, NC, USA
| | - A J Shaw
- Department of Biology, Duke University, Durham, NC, USA
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24
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Marie-Orleach L, Janicke T, Vizoso DB, David P, Schärer L. Quantifying episodes of sexual selection: Insights from a transparent worm with fluorescent sperm. Evolution 2016; 70:314-28. [PMID: 26787006 DOI: 10.1111/evo.12861] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 12/03/2015] [Accepted: 12/22/2015] [Indexed: 01/14/2023]
Abstract
Sexual selection operates through consecutive episodes of selection that ultimately contribute to the observed variance in reproductive success between individuals. Understanding the relative importance of these episodes is challenging, particularly because the relevant postcopulatory fitness components are often difficult to assess. Here, we investigate different episodes of sexual selection on the male sex function, by assessing how (precopulatory) mating success, and (postcopulatory) sperm-transfer efficiency and sperm-fertilizing efficiency contribute to male reproductive success. Specifically, we used a transgenic line of the transparent flatworm, Macrostomum lignano, which expresses green fluorescent protein (GFP) in all cell types, including sperm cells, enabling in vivo sperm tracking and paternity analysis. We found that a large proportion of variance in male reproductive success arose from the postcopulatory episodes. Moreover, we also quantified selection differentials on 10 morphological traits. Testis size and seminal vesicle size showed significant positive selection differentials, which were mainly due to selection on sperm-transfer efficiency. Overall, our results demonstrate that male reproductive success in M. lignano is not primarily limited by the number of matings achieved, but rather by the ability to convert matings into successful fertilizations, which is facilitated by producing many sperm.
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Affiliation(s)
- Lucas Marie-Orleach
- Zoological Institute, University of Basel, Basel, Switzerland. .,Centre for Biological Diversity, University of St Andrews, St Andrews, United Kingdom.
| | - Tim Janicke
- Zoological Institute, University of Basel, Basel, Switzerland.,Centre d'Écologie Fonctionnelle et Évolutive, Montpellier, France
| | - Dita B Vizoso
- Zoological Institute, University of Basel, Basel, Switzerland
| | - Patrice David
- Centre d'Écologie Fonctionnelle et Évolutive, Montpellier, France
| | - Lukas Schärer
- Zoological Institute, University of Basel, Basel, Switzerland
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25
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Janicke T, Häderer IK, Lajeunesse MJ, Anthes N. Darwinian sex roles confirmed across the animal kingdom. SCIENCE ADVANCES 2016; 2:e1500983. [PMID: 26933680 PMCID: PMC4758741 DOI: 10.1126/sciadv.1500983] [Citation(s) in RCA: 217] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/30/2015] [Indexed: 06/01/2023]
Abstract
Since Darwin's conception of sexual selection theory, scientists have struggled to identify the evolutionary forces underlying the pervasive differences between male and female behavior, morphology, and physiology. The Darwin-Bateman paradigm predicts that anisogamy imposes stronger sexual selection on males, which, in turn, drives the evolution of conventional sex roles in terms of female-biased parental care and male-biased sexual dimorphism. Although this paradigm forms the cornerstone of modern sexual selection theory, it still remains untested across the animal tree of life. This lack of evidence has promoted the rise of alternative hypotheses arguing that sex differences are entirely driven by environmental factors or chance. We demonstrate that, across the animal kingdom, sexual selection, as captured by standard Bateman metrics, is indeed stronger in males than in females and that it is evolutionarily tied to sex biases in parental care and sexual dimorphism. Our findings provide the first comprehensive evidence that Darwin's concept of conventional sex roles is accurate and refute recent criticism of sexual selection theory.
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Affiliation(s)
- Tim Janicke
- Centre d’Écologie Fonctionnelle et Évolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, École Pratique des Hautes Études, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
| | - Ines K. Häderer
- Animal Evolutionary Ecology Group, Institute for Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Marc J. Lajeunesse
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Nils Anthes
- Animal Evolutionary Ecology Group, Institute for Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
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26
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Turnell BR, Shaw KL. High opportunity for postcopulatory sexual selection under field conditions. Evolution 2015; 69:2094-104. [PMID: 26179824 DOI: 10.1111/evo.12721] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 06/20/2015] [Accepted: 06/29/2015] [Indexed: 01/02/2023]
Abstract
In polygamous systems, male fitness is determined not only by mating success but also by fertilization success. Despite the growing interest over the past several decades in postcopulatory sexual selection, its relative importance compared to precopulatory sexual selection remains a subject of debate. Here, we use extensive behavioral observations of a seminatural population of Hawaiian swordtail crickets, Laupala cerasina, and molecular paternity assignment to measure the opportunities for pre- and postcopulatory selection. Because postcopulatory selection has the potential to operate at multiple stages, we also separately attribute its effects to factors specific to mating events versus factors specific to males. We find that variance in postcopulatory success is over four times as great as variance in precopulatory success, with most of it unexplained by male mating order or the number of nuptial gifts given. Surprisingly, we also find that male singing effort is under postcopulatory selection, suggesting that males who sing more frequently also have more competitive ejaculates. Our results are consistent with the hypothesis that high polyandry levels promote greater relative postcopulatory selection. They also highlight the need for detailed behavioral observations under conditions as natural as possible when measuring mating and reproductive success.
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Affiliation(s)
- Biz R Turnell
- Cornell University, W343 Seeley G. Mudd Hall, Ithaca, New York, 14853.
| | - Kerry L Shaw
- Cornell University, W317 Seeley G. Mudd Hall, Ithaca, New York, 14853.
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27
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Janssen R, Baur B. Seasonal effects on egg production and level of paternity in a natural population of a simultaneous hermaphrodite snail. Ecol Evol 2015; 5:2916-28. [PMID: 26306176 PMCID: PMC4541995 DOI: 10.1002/ece3.1560] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2014] [Revised: 05/10/2015] [Accepted: 05/19/2015] [Indexed: 11/22/2022] Open
Abstract
In a seasonal environment, the suitable time window for females to reproduce is restricted by both environmental conditions and the availability of males. In simultaneous hermaphrodites, which are female and male at the same time, selection on a trait that is solely beneficial for one sexual function cannot occur independently. Therefore, it is assumed that the optimal time window for reproduction is a compromise between the two sexual functions in simultaneous hermaphrodites, mediated by environmental conditions. We examined seasonal patterns of reproduction and the resulting paternity in a natural population of the simultaneously hermaphroditic land snail Arianta arbustorum. Adult and premature individuals (snails in a short protandric phase) were collected on four occasions over the entire active season. The snails were allowed to deposit eggs after which we assessed the level of paternity in their hatched offspring. Individuals mated throughout the reproductive season, whereas egg production - the major task of the female function - was restricted to the first half of the season. Snails collected in autumn were allowed to hibernate under laboratory conditions. As a result, we found that premature individuals began to mate late in the reproductive season, but did not start to produce eggs before emerging from hibernation. Our results demonstrate a temporal shift of reproductive activities; the egg production and oviposition occur mainly in the first half of the season, while sperm production and mating occur over the entire season. In subadult and adult snails, sperm obtained from several partners in the second part of the reproductive season are stored during hibernation for the fertilization of eggs in the successive years. These results extend our understanding of the influence of both natural and sexual selection on reproductive strategies in hermaphrodites.
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Affiliation(s)
- Ruben Janssen
- Section of Conservation Biology, Department of Environmental Sciences, University of BaselSt. Johanns-Vorstadt 10, CH-4056, Basel, Switzerland
| | - Bruno Baur
- Section of Conservation Biology, Department of Environmental Sciences, University of BaselSt. Johanns-Vorstadt 10, CH-4056, Basel, Switzerland
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Janssen T, Vizoso DB, Schulte G, Littlewood DTJ, Waeschenbach A, Schärer L. The first multi-gene phylogeny of the Macrostomorpha sheds light on the evolution of sexual and asexual reproduction in basal Platyhelminthes. Mol Phylogenet Evol 2015; 92:82-107. [PMID: 26093054 DOI: 10.1016/j.ympev.2015.06.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 05/11/2015] [Accepted: 06/09/2015] [Indexed: 11/19/2022]
Abstract
The Macrostomorpha-an early branching and species-rich clade of free-living flatworms-is attracting interest because it contains Macrostomum lignano, a versatile model organism increasingly used in evolutionary, developmental, and molecular biology. We elucidate the macrostomorphan molecular phylogeny inferred from both nuclear (18S and 28S rDNA) and mitochondrial (16S rDNA and COI) marker genes from 40 representatives. Although our phylogeny does not recover the Macrostomorpha as a statistically supported monophyletic grouping, it (i) confirms many taxa previously proposed based on morphological evidence, (ii) permits the first placement of many families and genera, and (iii) reveals a number of unexpected placements. Specifically, Myozona and Bradynectes are outside the three classic families (Macrostomidae, Microstomidae and Dolichomacrostomidae) and the asexually fissioning Myomacrostomum belongs to a new subfamily, the Myozonariinae nov. subfam. (Dolichomacrostomidae), rather than diverging early. While this represents the first evidence for asexuality among the Dolichomacrostomidae, we show that fissioning also occurs in another Myozonariinae, Myozonaria fissipara nov. sp. Together with the placement of the (also fissioning) Microstomidae, namely as the sister taxon of Dolichomacrostomidae, this suggests that fissioning is not basal within the Macrostomorpha, but rather restricted to the new taxon Dolichomicrostomida (Dolichomacrostomidae+Microstomidae). Furthermore, our phylogeny allows new insights into the evolution of the reproductive system, as ancestral state reconstructions reveal convergent evolution of gonads, and male and female genitalia. Finally, the convergent evolution of sperm storage organs in the female genitalia appears to be linked to the widespread occurrence of hypodermic insemination among the Macrostomorpha.
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Affiliation(s)
- Toon Janssen
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland; Nematology Research Unit, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium.
| | - Dita B Vizoso
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Gregor Schulte
- Animal Evolutionary Ecology, Institute for Evolution and Ecology, University Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | | | - Andrea Waeschenbach
- Natural History Museum, Life Sciences Department, Cromwell Rd, London SW7 5BD, UK
| | - Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
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29
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Fitzpatrick CL. Expanding Sexual Selection Gradients; A Synthetic Refinement of Sexual Selection Theory. Ethology 2015. [DOI: 10.1111/eth.12352] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Hermaphrodites combine the male and female sex functions into a single individual, either sequentially or simultaneously. This simple fact means that they exhibit both similarities and differences in the way in which they experience, and respond to, sexual conflict compared to separate-sexed organisms. Here, we focus on clarifying how sexual conflict concepts can be adapted to apply to all anisogamous sexual systems and review unique (or especially important) aspects of sexual conflict in hermaphroditic animals. These include conflicts over the timing of sex change in sequential hermaphrodites, and in simultaneous hermaphrodites, over both sex roles and the postmating manipulation of the sperm recipient by the sperm donor. Extending and applying sexual conflict thinking to hermaphrodites can identify general evolutionary principles and help explain some of the unique reproductive diversity found among animals exhibiting this widespread but to date understudied sexual system.
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Affiliation(s)
- Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, 4051 Basel, Switzerland
| | - Tim Janicke
- Centre d'Écologie Fonctionnelle et Évolutive, CNRS UMR 5175, 34293 Montpellier Cedex 05, France
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, 33615 Bielefeld, Germany
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31
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Carvalho S, Chelo IM, Goy C, Teotónio H. The role of hermaphrodites in the experimental evolution of increased outcrossing rates in Caenorhabditis elegans. BMC Evol Biol 2014; 14:116. [PMID: 24891031 PMCID: PMC4055231 DOI: 10.1186/1471-2148-14-116] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 05/21/2014] [Indexed: 01/16/2023] Open
Abstract
Background Why most organisms reproduce via outcrossing rather than selfing is a central question in evolutionary biology. It has long ago been suggested that outcrossing is favoured when it facilitates adaptation to novel environments. We have previously shown that the experimental evolution of increased outcrossing rates in populations of the male-hermaphrodite nematode Caenorhabditis elegans were correlated with the experimental evolution of increased male fitness. However, it is unknown whether outcrossing led to adaptation, and if so, which fitness components can explain the observed increase in outcrossing rates. Results Using experimental evolution in six populations with initially low standing levels of genetic diversity, we show with head-to-head competition assays that population-wide fitness improved during 100 generations. Since outcrossing rates increased during the same period, this result demonstrates that outcrossing is adaptive. We also show that there was little evolution of hermaphrodite fitness under conditions of selfing or under conditions of outcrossing with unrelated tester males. We nonetheless find a positive genetic correlation between hermaphrodite self-fitness and population-wide fitness, and a negative genetic correlation between hermaphrodite mating success and population-wide fitness. These results suggest that the several hermaphrodite traits measured are fitness components. Tradeoffs expressed in hermaphrodites, particularly noticed between self-fitness and mating success, may in turn explain their lack of change during experimental evolution. Conclusions Our findings indicate that outcrossing facilitates adaptation to novel environments. They further indicate that the experimental evolution of increased outcrossing rates depended little on hermaphrodites because of fitness tradeoffs between selfing and outcrossing. Instead, the evolution of increased outcrossing rates appears to have resulted from unhindered selection on males.
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32
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Carvalho S, Phillips PC, Teotónio H. Hermaphrodite life history and the maintenance of partial selfing in experimental populations of Caenorhabditis elegans. BMC Evol Biol 2014; 14:117. [PMID: 24891140 PMCID: PMC4052797 DOI: 10.1186/1471-2148-14-117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 05/21/2014] [Indexed: 01/18/2023] Open
Abstract
Background Classic population genetics theory predicts that mixed reproductive systems, where self reproduction (selfing) and outcrossing co-exist, should not be as common as they are in nature. One means of reconciling theory with observations is to recognize that sexual conflict between males and hermaphrodites and/or constraints in the allocation of resources towards sex functions in hermaphrodites can balance the fitness components of selfing and outcrossing. Results Using experimental evolution in Caenorhabditis elegans, we test whether the adaptive maintenance of partial selfing is due to sexual conflict and/or to the evolution of sex allocation towards male function in hermaphrodites. For this, we characterized the reproductive schedule and longevity patterns in hermaphrodites under selfing and under outcrossing with naïve males that did not have the opportunity to evolve with them. A shift in reproductive schedule towards earlier reproduction would be indicative of adaptation in our imposed life-cycle, while longevity is expected to evolve as a response to the harm that males impinge on hermaphrodites upon mating. To determine adaptation in the absence of constraints in sex allocation, we also characterized the life history of females that reproduced during experimental evolution through obligate mating with males. As expected with adaptation, we find that after 100 generations of experimental evolution, selfing hermaphrodites and females showed improved reproduction at earlier ages. We did not observe similar reproductive shifts in outcrossed hermaphrodites. We further find increased longevity in outcrossed females after evolution but not in outcrossed hermaphrodites, a result that indicates that sexual conflicts were likely more prevalent under male–female evolution than under male-hermaphrodite evolution. Conclusions Taken together, our findings suggest that the adaptive maintenance of partial selfing during C. elegans experimental evolution resulted from the evolution of sex allocation towards male function in hermaphrodites.
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Affiliation(s)
| | | | - Henrique Teotónio
- Instituto Gulbenkian de Ciência, Apartado 14, P-2781-901 Oeiras, Portugal.
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33
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Collet JM, Dean RF, Worley K, Richardson DS, Pizzari T. The measure and significance of Bateman's principles. Proc Biol Sci 2014; 281:20132973. [PMID: 24648220 PMCID: PMC3973258 DOI: 10.1098/rspb.2013.2973] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/20/2014] [Indexed: 11/12/2022] Open
Abstract
Bateman's principles explain sex roles and sexual dimorphism through sex-specific variance in mating success, reproductive success and their relationships within sexes (Bateman gradients). Empirical tests of these principles, however, have come under intense scrutiny. Here, we experimentally show that in replicate groups of red junglefowl, Gallus gallus, mating and reproductive successes were more variable in males than in females, resulting in a steeper male Bateman gradient, consistent with Bateman's principles. However, we use novel quantitative techniques to reveal that current methods typically overestimate Bateman's principles because they (i) infer mating success indirectly from offspring parentage, and thus miss matings that fail to result in fertilization, and (ii) measure Bateman gradients through the univariate regression of reproductive over mating success, without considering the substantial influence of other components of male reproductive success, namely female fecundity and paternity share. We also find a significant female Bateman gradient but show that this likely emerges as spurious consequences of male preference for fecund females, emphasizing the need for experimental approaches to establish the causal relationship between reproductive and mating success. While providing qualitative support for Bateman's principles, our study demonstrates how current approaches can generate a misleading view of sex differences and roles.
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Affiliation(s)
- Julie M. Collet
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
- School of Biological Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
- Department of Genetics, Evolution and Environment, University College London, The Darwin Building, Gower Street, London WC1E 6BT, UK
| | - Rebecca F. Dean
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
- Department of Genetics, Evolution and Environment, University College London, The Darwin Building, Gower Street, London WC1E 6BT, UK
- Department of Evolutionary Biology, Uppsala University, Norbyvägen 18D, Uppsala 752 36, Sweden
| | - Kirsty Worley
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
- Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - David S. Richardson
- Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Tommaso Pizzari
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, UK
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34
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Di Bona V, Minetti C, Trotta V, Sella G, Lorenzi M. A trade-off between traits that contribute to male and female function in hermaphrodites. ETHOL ECOL EVOL 2014. [DOI: 10.1080/03949370.2014.880162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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35
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Pélissié B, Jarne P, Sarda V, David P. DISENTANGLING PRECOPULATORY AND POSTCOPULATORY SEXUAL SELECTION IN POLYANDROUS SPECIES. Evolution 2014; 68:1320-31. [DOI: 10.1111/evo.12353] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 12/12/2013] [Indexed: 10/25/2022]
Affiliation(s)
- Benjamin Pélissié
- Centre d’Ecologie Fonctionnelle et Evolutive (CEFE); UMR 5175, campus CNRS, 1919 Route de Mende 34293 Montpellier Cedex 5 France
| | - Philippe Jarne
- Centre d’Ecologie Fonctionnelle et Evolutive (CEFE); UMR 5175, campus CNRS, 1919 Route de Mende 34293 Montpellier Cedex 5 France
| | - Violette Sarda
- Centre d’Ecologie Fonctionnelle et Evolutive (CEFE); UMR 5175, campus CNRS, 1919 Route de Mende 34293 Montpellier Cedex 5 France
| | - Patrice David
- Centre d’Ecologie Fonctionnelle et Evolutive (CEFE); UMR 5175, campus CNRS, 1919 Route de Mende 34293 Montpellier Cedex 5 France
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36
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Janicke T, Vellnow N, Lamy T, Chapuis E, David P. Inbreeding depression of mating behavior and its reproductive consequences in a freshwater snail. Behav Ecol 2013. [DOI: 10.1093/beheco/art122] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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37
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Lorenzi MC, Schleicherová D, Sella G. Multiple paternity and mate competition in non-selfing, monogamous, egg-trading hermaphrodites. Acta Ethol 2013. [DOI: 10.1007/s10211-013-0169-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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38
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Chelo IM, Carvalho S, Roque M, Proulx SR, Teotónio H. The genetic basis and experimental evolution of inbreeding depression in Caenorhabditis elegans. Heredity (Edinb) 2013; 112:248-54. [PMID: 24129606 PMCID: PMC3931175 DOI: 10.1038/hdy.2013.100] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 09/11/2013] [Accepted: 09/12/2013] [Indexed: 01/24/2023] Open
Abstract
Determining the genetic basis of inbreeding depression is important for understanding the
role of selection in the evolution of mixed breeding systems. Here, we investigate how
androdioecy (a breeding system characterized by partial selfing and outcrossing) and
dioecy (characterized by obligatory outcrossing) influence the experimental evolution of
inbreeding depression in Caenorhabditis elegans. We derived inbred lines from
ancestral and evolved populations and found that the dioecious lineages underwent more
extinction than androdioecious lineages. For both breeding systems, however, there was
selection during inbreeding because the diversity patterns of 337 single-nucleotide
polymorphisms (SNPs) among surviving inbred lines deviated from neutral expectations. In
parallel, we also followed the evolution of embryo to adult viability, which revealed
similar starting levels of inbreeding depression in both breeding systems, but also
outbreeding depression. Under androdioecy, diversity at a neutral subset of 134 SNPs
correlated well with the viability trajectories, showing that the population genetic
structure imposed by partial selfing affected the opportunity for different forms of
selection. Our findings suggest that the interplay between the disruptions of coevolved
sets of loci by outcrossing, the efficient purging of deleterious recessive alleles with
selfing and overdominant selection with outcrossing can help explain mixed breeding
systems.
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Affiliation(s)
- I M Chelo
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - S Carvalho
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - M Roque
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - S R Proulx
- Department of Ecology Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - H Teotónio
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
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39
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Dai C, Galloway LF. Sexual selection in a hermaphroditic plant through female reproductive success. J Evol Biol 2013; 26:2622-32. [DOI: 10.1111/jeb.12254] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 07/22/2013] [Accepted: 08/26/2013] [Indexed: 11/29/2022]
Affiliation(s)
- C. Dai
- Department of Biology; University of Virginia; Charlottesville VA USA
- School of Resources and Environmental Science; Hubei University; Wuhan China
| | - L. F. Galloway
- Department of Biology; University of Virginia; Charlottesville VA USA
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40
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Koene JM, Liew TS, Montagne-Wajer K, Schilthuizen M. A syringe-like love dart injects male accessory gland products in a tropical hermaphrodite. PLoS One 2013; 8:e69968. [PMID: 23894565 PMCID: PMC3722094 DOI: 10.1371/journal.pone.0069968] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 06/13/2013] [Indexed: 11/19/2022] Open
Abstract
Sexual conflict shapes the evolution of many behaviours and processes involved in reproduction. Nearly all evidence supporting this comes from species where the sexes are separated. However, a substantial proportion of animals and most plants are hermaphroditic, and theoretical work predicts that sexual conflict plays an important role even when the sexes are joined within one individual. This seems to have resulted in bizarre mating systems, sophisticated sperm packaging and complex reproductive morphologies. By far the best-known example of such a strategy in hermaphrodites is the shooting of so-called love-darts in land snails. All known love darts carry a gland product on their outside and enter this into the partner's hemolymph by stabbing. Here, we show that species of the snail genus Everettia possess a syringe-like dart that serves as a real injection needle. Their dart is round in cross-section, contains numerous channels, and has perforations along its side. Histology and electron microscopy show that these holes connect to the channels inside the dart and run all the way up to the elaborate mucus glands that are attached to the dart sac. This is the first report on a love dart that is used as a syringe to directly inject the gland product into the partner's hemolymph. Although the exact use and function of this dart remains to be demonstrated, this clearly adds to the complexity of the evolution of reproductive strategies in hermaphrodites in general. Moreover, the perforations on the outside of the love dart resemble features of other injection devices, thus uncovering common design and repeated evolution of such features in animals.
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Affiliation(s)
- Joris M Koene
- Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University, Amsterdam, The Netherlands.
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41
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Nakadera Y, Koene JM. Reproductive strategies in hermaphroditic gastropods: conceptual and empirical approaches. CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0272] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An individual optimizes its reproductive success by adopting a particular reproductive strategy. Studying the details of a reproductive strategy leads to an understanding of how sexual selection acts, as the former is the process via which the individual reproduces successfully. Hermaphroditic gastropods display a bewildering diversity of reproductive strategies, which may be due to their mode of gender expression, when compared with well-studied separate-sexed species. Extensive theoretical, observational, and experimental research has been conducted on this topic. However, despite our knowledge about the reproductive system of hermaphroditic gastropods, we still need to fill the gap between pre- and post-copulatory processes and reproductive success. Here, we review and propose conceptual and empirical approaches aimed at understanding reproductive strategies of hermaphroditic gastropods. In sum, our suggestions are (i) to focus on sex-biased traits, (ii) to take biologically reliable measurements at both the pre- and post-copulatory level that relate to reproductive success, and (iii) to examine the fitness consequences of biased sex allocation.
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Affiliation(s)
- Yumi Nakadera
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081HV, Amsterdam, the Netherlands
| | - Joris M. Koene
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081HV, Amsterdam, the Netherlands
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42
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Lorenzi MC, Sella G. In Between Breeding Systems: Neither Dioecy Nor Androdioecy Explains Sexual Polymorphism in Functionally Dioecious Worms. Integr Comp Biol 2013; 53:689-700. [DOI: 10.1093/icb/ict043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Bergeron P, Martin AM, Garant D, Pelletier F. Comment on “Bateman in Nature: Predation on Offspring Reduces the Potential for Sexual Selection”. Science 2013; 340:549. [DOI: 10.1126/science.1233246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- P. Bergeron
- Life Sciences Center, Dartmouth College, Hanover, NH, 03755, USA
| | - A. M. Martin
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Qc, J1K 2R1, Canada
| | - D. Garant
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Qc, J1K 2R1, Canada
| | - F. Pelletier
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Qc, J1K 2R1, Canada
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44
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Arnqvist G. Comment on “Bateman in Nature: Predation on Offspring Reduces the Potential for Sexual Selection”. Science 2013; 340:549. [DOI: 10.1126/science.1233413] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Göran Arnqvist
- Animal Ecology, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE75236 Uppsala, Sweden
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45
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Nieuwenhuis BPS, Aanen DK. Sexual selection in fungi. J Evol Biol 2013; 25:2397-411. [PMID: 23163326 DOI: 10.1111/jeb.12017] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 09/07/2012] [Accepted: 09/07/2012] [Indexed: 12/14/2022]
Abstract
The significance of sexual selection, the component of natural selection associated with variation in mating success, is well established for the evolution of animals and plants, but not for the evolution of fungi. Even though fungi do not have separate sexes, most filamentous fungi mate in a hermaphroditic fashion, with distinct sex roles, that is, investment in large gametes (female role) and fertilization by other small gametes (male role). Fungi compete to fertilize, analogous to 'male-male' competition, whereas they can be selective when being fertilized, analogous to female choice. Mating types, which determine genetic compatibility among fungal gametes, are important for sexual selection in two respects. First, genes at the mating-type loci regulate different aspects of mating and thus can be subject to sexual selection. Second, for sexual selection, not only the two sexes (or sex roles) but also the mating types can form the classes, the members of which compete for access to members of the other class. This is significant if mating-type gene products are costly, thus signalling genetic quality according to Zahavi's handicap principle. We propose that sexual selection explains various fungal characteristics such as the observed high redundancy of pheromones at the B mating-type locus of Agaricomycotina, the occurrence of multiple types of spores in Ascomycotina or the strong pheromone signalling in yeasts. Furthermore, we argue that fungi are good model systems to experimentally study fundamental aspects of sexual selection, due to their fast generation times and high diversity of life cycles and mating systems.
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Affiliation(s)
- B P S Nieuwenhuis
- Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands.
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46
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Schärer L, Pen I. Sex allocation and investment into pre- and post-copulatory traits in simultaneous hermaphrodites: the role of polyandry and local sperm competition. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120052. [PMID: 23339243 PMCID: PMC3576586 DOI: 10.1098/rstb.2012.0052] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sex allocation theory predicts the optimal allocation to male and female reproduction in sexual organisms. In animals, most work on sex allocation has focused on species with separate sexes and our understanding of simultaneous hermaphrodites is patchier. Recent theory predicts that sex allocation in simultaneous hermaphrodites should strongly be affected by post-copulatory sexual selection, while the role of pre-copulatory sexual selection is much less clear. Here, we review sex allocation and sexual selection theory for simultaneous hermaphrodites, and identify several strong and potentially unwarranted assumptions. We then present a model that treats allocation to sexually selected traits as components of sex allocation and explore patterns of allocation when some of these assumptions are relaxed. For example, when investment into a male sexually selected trait leads to skews in sperm competition, causing local sperm competition, this is expected to lead to a reduced allocation to sperm production. We conclude that understanding the evolution of sex allocation in simultaneous hermaphrodites requires detailed knowledge of the different sexual selection processes and their relative importance. However, little is currently known quantitatively about sexual selection in simultaneous hermaphrodites, about what the underlying traits are, and about what drives and constrains their evolution. Future work should therefore aim at quantifying sexual selection and identifying the underlying traits along the pre- to post-copulatory axis.
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Affiliation(s)
- Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland.
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47
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Shuster SM, Briggs WR, Dennis PA. How multiple mating by females affects sexual selection. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120046. [PMID: 23339237 DOI: 10.1098/rstb.2012.0046] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Multiple mating by females is widely thought to encourage post-mating sexual selection and enhance female fitness. We show that whether polyandrous mating has these effects depends on two conditions. Condition 1 is the pattern of sperm utilization by females; specifically, whether, among females, male mating number, m (i.e. the number of times a male mates with one or more females) covaries with male offspring number, o. Polyandrous mating enhances sexual selection only when males who are successful at multiple mating also sire most or all of each of their mates' offspring, i.e. only when Cov(♂)(m,o), is positive. Condition 2 is the pattern of female reproductive life-history; specifically, whether female mating number, m, covaries with female offspring number, o. Only semelparity does not erode sexual selection, whereas iteroparity (i.e. when Cov(♀)(m,o), is positive) always increases the variance in offspring numbers among females, which always decreases the intensity of sexual selection on males. To document the covariance between mating number and offspring number for each sex, it is necessary to assign progeny to all parents, as well as identify mating and non-mating individuals. To document significant fitness gains by females through iteroparity, it is necessary to determine the relative magnitudes of male as well as female contributions to the total variance in relative fitness. We show how such data can be collected, how often they are collected, and we explain the circumstances in which selection favouring multiple mating by females can be strong or weak.
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Affiliation(s)
- Stephen M Shuster
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA.
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48
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Kelly MW, Grosberg RK, Sanford E. Love the one you're with: proximity determines paternity success in the barnacleTetraclita rubescens. Mol Ecol 2012; 21:5088-97. [DOI: 10.1111/mec.12009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 07/13/2012] [Accepted: 07/23/2012] [Indexed: 11/26/2022]
Affiliation(s)
| | - Richard K. Grosberg
- Department of Evolution and Ecology; University of California; Davis; CA; 95616; USA
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Lange R, Gerlach T, Beninde J, Werminghausen J, Reichel V, Anthes N. Female fitness optimum at intermediate mating rates under traumatic mating. PLoS One 2012; 7:e43234. [PMID: 22937024 PMCID: PMC3425583 DOI: 10.1371/journal.pone.0043234] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 07/18/2012] [Indexed: 11/24/2022] Open
Abstract
Traumatic mating behaviors often bear signatures of sexual conflict and are then typically considered a male strategy to circumvent female choice mechanisms. In an extravagant mating ritual, the hermaphroditic sea slug Siphopteron quadrispinosum pierces the integument of their mating partners with a syringe-like penile stylet that injects prostate fluids. Traumatic injection is followed by the insertion of a spiny penis into the partner’s gonopore to transfer sperm. Despite traumatic mating, field mating rates exceed those required for female fertilization insurance, possibly because costs imposed on females are balanced by direct or indirect benefits of multiple sperm receipt. To test this idea, we exposed animals to a relevant range of mating opportunity regimes and assessed the effects on mating behavior and proxies of female fitness. We find penis intromission duration to decrease with mating rates, and a female fecundity maximum at intermediate mating rates. The latter finding indicates that benefits beyond fertilization insurance can make higher mating rates also beneficial from a female perspective in this traumatically mating species.
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Affiliation(s)
- Rolanda Lange
- Animal Evolutionary Ecology Group, Faculty of Sciences, University of Tuebingen, Tuebingen, Germany.
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50
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Hoffer JN, Schwegler D, Ellers J, Koene JM. Mating rate influences female reproductive investment in a simultaneous hermaphrodite, Lymnaea stagnalis. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.06.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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