1
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Macedo-Rego RC, Jennions MD, Santos ESA. Does the potential strength of sexual selection differ between mating systems with and without defensive behaviours? A meta-analysis. Biol Rev Camb Philos Soc 2024; 99:1504-1523. [PMID: 38597347 DOI: 10.1111/brv.13078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 04/11/2024]
Abstract
The Darwin-Bateman paradigm predicts that females enhance their fitness by being choosy and mating with high-quality males, while males should compete to mate with as many females as possible. In many species, males enhance their fitness by defending females and/or resources used by females. That is, males directly defend access to mating opportunities. However, paternity analyses have repeatedly shown that females in most species mate polyandrously, which contradicts traditional expectations that male defensive behaviours lead to monandry. Here, in an extensive meta-analysis, encompassing 109 species and 1026 effect sizes from across the animal kingdom, we tested if the occurrence of defensive behaviours modulates sexual selection on females and males. If so, we can illuminate the extent to which males really succeed in defending access to mating and fertilisation opportunities. We used four different indices of the opportunity for sexual selection that comprise pre-mating and/or post-mating episodes of selection. We found, for both sexes, that the occurrence of defensive behaviours does not modulate the potential strength of sexual selection. This implies that male defensive behaviours do not predict the true intensity of sexual selection. While the most extreme levels of sexual selection on males are in species with male defensive behaviours, which indicates that males do sometimes succeed in restricting females' re-mating ability (e.g. elephant seals, Mirounga leonina), estimates of the opportunity for sexual selection vary greatly across species, regardless of whether or not defensive behaviours occur. Indeed, widespread polyandry shows that females are usually not restricted by male defensive behaviours. In addition, our results indicate that post-mating episodes of selection, such as cryptic female choice and sperm competition, might be important factors modulating the opportunity for sexual selection. We discuss: (i) why male defensive behaviours fail to lower the opportunity for sexual selection among females or fail to elevate it for males; (ii) how post-mating events might influence sexual selection; and (iii) the role of females as active participants in sexual selection. We also highlight that inadequate data reporting in the literature prevented us from extracting effect sizes from many studies that had presumably collected the relevant data.
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Affiliation(s)
- Renato C Macedo-Rego
- Programa de Pós-graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, no. 321, São Paulo, SP 05508-090, Brazil
- Division of Ecology & Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Michael D Jennions
- Division of Ecology & Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Centre, 10 Marais Street, Stellenbosch, 7600, South Africa
| | - Eduardo S A Santos
- Programa de Pós-graduação em Ecologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, no. 321, São Paulo, SP 05508-090, Brazil
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2
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Santhosh S, Ebert D, Janicke T. Sperm competition favours intermediate sperm size in a hermaphrodite1. J Evol Biol 2024; 37:829-838. [PMID: 38738700 DOI: 10.1093/jeb/voae058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/22/2024] [Accepted: 05/10/2024] [Indexed: 05/14/2024]
Abstract
Sperm competition is a potent mechanism of postcopulatory sexual selection that has been found to shape reproductive morphologies and behaviours in promiscuous animals. Especially sperm size has been argued to evolve in response to sperm competition through its effect on sperm longevity, sperm motility, the ability to displace competing sperm, and ultimately fertilization success. Additionally, sperm size has been observed to co-evolve with female reproductive morphology. Theoretical work predicts that sperm competition may select for longer sperm but may also favour shorter sperm if sperm size trades-off with number. In this study, we studied the relationship between sperm size and postmating success in the free-living flatworm, Macrostomum lignano. Specifically, we used inbred isolines of M. lignano that varied in sperm size to investigate how sperm size translated into the ability of worms to transfer and deposit sperm in a mating partner. Our results revealed a hump-shaped relationship with individuals producing sperm of intermediate size having the highest sperm competitiveness. This finding broadens our understanding of the evolution of sperm morphology by providing empirical support for stabilizing selection on sperm size under sperm competition.
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Affiliation(s)
- Santhosh Santhosh
- Department of Environmental Sciences, Zoology, University of Basel, CH-4 4051 Basel, Switzerland
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, CH-4 4051 Basel, Switzerland
| | - Tim Janicke
- Centre d'Ecologie Fonctionelle et Evolutive, Univ. Montpellier, CNRS, EPHE, IRD, 34293 Montpellier Cedex 05, France
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3
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Brand JN. Support for a radiation of free-living flatworms in the African Great Lakes region and the description of five new Macrostomum species. Front Zool 2023; 20:31. [PMID: 37670326 PMCID: PMC10478486 DOI: 10.1186/s12983-023-00509-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/14/2023] [Indexed: 09/07/2023] Open
Abstract
BACKGROUND The African Great Lakes have long been recognized as an excellent location to study speciation. Most famously, cichlid fishes have radiated in Lake Tanganyika and subsequently spread into Lake Malawi and Lake Victoria, where they again radiated. Other taxa have diversified in these lakes, such as catfish, ostracods, gastropods, and Monegenean gill parasites of cichlids. However, these radiations have received less attention, and the process leading to their speciation in this unique region remains to be further explored. Here I present evidence that suggests a radiation of Macrostomum flatworms has occurred in the African Great Lakes region, offering a good opportunity for such investigations. RESULTS Recent field work has revealed a monophyletic clade of 16 Macrostomum flatworms that have, to date, only been collected from Lake Tanganyika. Additionally, a species collected from Lake Malawi was found nested within this clade. Molecular phylogenetic analysis, largely based on transcriptome data, suggests that this clade underwent rapid speciation, possibly due to a large habitat diversity in the lake. I also observed significant differences in the sperm morphology of these flatworms compared to those of species found outside Lake Tanganyika and Lake Malawi. These included the elongation of an anterior structure, a reduction in the size of the lateral sperm bristles, and changes in relative proportions. I propose functional hypotheses for these changes in sperm design, and formally describe Macrostomum gracilistylum sp. nov from Lake Malawi and its sister species Macrostomum crassum sp. nov., Macrostomum pellitum sp. nov., Macrostomum longispermatum sp. nov., and Macrostomum schäreri sp. nov., from Lake Tanganyika. CONCLUSIONS The available evidence is consistent with the hypothesis that Macrostomum flatworms have radiated in Lake Tanganyika and subsequently spread to Lake Malawi. However, whether this represents a bona fide adaptive radiation still needs to be determined. Therefore, the African Great Lakes are promising targets for further research into flatworm diversity and speciation.
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Affiliation(s)
- Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, Basel, 4051, Switzerland.
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Science, Am Fassberg 11, 37077, Göttingen, Germany.
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4
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McDonald GC. The impact of small groups on pre- and postcopulatory sexual selection in polyandrous populations. Ecol Evol 2023; 13:e10057. [PMID: 37153025 PMCID: PMC10154804 DOI: 10.1002/ece3.10057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 04/08/2023] [Accepted: 04/19/2023] [Indexed: 05/09/2023] Open
Abstract
Sexual selection is a key evolutionary force but varies widely between populations. Two key factors that influence sexual selection are the extent to which females copulate with multiple males (polyandry) and variation in the social environment. Increasing research demonstrates populations are structured by complex socio-sexual networks, and the structure of these networks can influence sexual selection by shaping the relationship between male precopulatory mating success and the intensity of postcopulatory competition. However, comparatively less attention has been dedicated to the influence of group structure on sexual selection and how differences in the size of groups may impact on the relative force of pre- and postcopulatory sexual selection in polyandrous populations. The presence of groups (i.e., group structure) and the size of groups varies widely in nature and forms an implicit part of much experimental sexual selection research under laboratory conditions. Here I use simulations of mating competition within populations that vary in the size of groups they contain, to show that variation in group size, and in particular small groups, can influence sexual selection. Specifically, I show that null expectations for the operation of pre- and postcopulatory sexual selection is governed by the size of groups within populations because smaller group sizes constrain the structure of sexual networks leading to reinforcing episodes of pre- and postcopulatory sexual selection. Given broad variation in group structure in nature and the tendency for experimental sexual selection research to study replicate small groups, these effects have implications for our understanding of the operation of sexual selection in polyandrous populations.
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Affiliation(s)
- Grant C. McDonald
- Department of EcologyUniversity of Veterinary Medicine BudapestBudapestHungary
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5
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Aguilar P, Dag B, Carazo P, Sultanova Z. Sex-specific paternal age effects on offspring quality in Drosophila melanogaster. J Evol Biol 2023; 36:720-729. [PMID: 36946550 DOI: 10.1111/jeb.14167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 12/15/2022] [Accepted: 12/19/2022] [Indexed: 03/23/2023]
Abstract
Advanced paternal age has been repeatedly shown to modulate offspring quality via male- and/or female-driven processes, and there are theoretical reasons to expect that some of these effects can be sex-specific. For example, sex allocation theory predicts that, when mated with low-condition males, mothers should invest more in their daughters compared to their sons. This is because male fitness is generally more condition-dependent and more variable than female fitness, which makes it less risky to invest in female offspring. Here, we explore whether paternal age can affect the quality and quantity of offspring in a sex-specific way using Drosophila melanogaster as a model organism. In order to understand the contribution of male-driven processes on paternal age effects, we also measured the seminal vesicle size of young and older males and explored its relationship with reproductive success and offspring quality. Older males had lower competitive reproductive success, as expected, but there was no difference between the offspring sex ratio of young and older males. However, we found that paternal age caused an increase in offspring quality (i.e., offspring weight), and that this increase was more marked in daughters than sons. We discuss different male- and female-driven processes that may explain such sex-specific paternal age effects.
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Affiliation(s)
- Prem Aguilar
- CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Porto, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, Porto, Portugal
| | - Berfin Dag
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Bogazici University, Istanbul, Turkey
| | - Pau Carazo
- Cavanilles Institute of Biodiversity and Evolutionary Biology, Valencia, Spain
| | - Zahida Sultanova
- School of Biological Sciences, University of East Anglia, Norwich, UK
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6
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Sexual selection in females and the evolution of polyandry. PLoS Biol 2023; 21:e3001916. [PMID: 36626380 PMCID: PMC9831318 DOI: 10.1371/journal.pbio.3001916] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 11/14/2022] [Indexed: 01/11/2023] Open
Abstract
Over the last decades, the field of sexual selection underwent a paradigm shift from sexual-stereotype thinking of "eager" males and "coy" females towards a more nuanced perspective acknowledging that not only males but also females can benefit from multiple mating and compete for mating partners. Yet, sexual selection in females is still considered a peculiarity, and the evolution of polyandry is often viewed to result from a higher mating interest of males. Here, we present meta-analytic evidence from 77 species across a broad range of animal taxa to demonstrate that female reproductive success is overall positively correlated with mating success, suggesting that females typically benefit from multiple mating. Importantly, we found that these fitness gains likely promote the evolution of polyandry. Our findings offer support for the idea that sexual selection is widespread in females and to play a key role for the evolution of animal mating systems. Thereby, our results extend our understanding of the evolutionary consequences of sexual reproduction and contribute to a more balanced view of how sexual selection operates in males and females.
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7
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Chechi TS, Narasimhan A, Biswas B, Prasad NG. Male mating success evolves in response to increased levels of male-male competition. Evolution 2022; 76:1638-1651. [PMID: 35598115 DOI: 10.1111/evo.14501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 02/25/2022] [Accepted: 03/04/2022] [Indexed: 01/22/2023]
Abstract
Male-biased operational sex ratios can increase male-male competition and can potentially select for both increased pre- and postcopulatory male success. In the present study, using populations of Drosophila melanogaster evolved under male-biased (M) or female-biased (F) sex ratios, we asked whether (a) male mating success can evolve, (b) males are better at mating females that they have coevolved with, (c) males mating success is affected by female mating status, and (d) male mating success is correlated with their courtship effort. We directly competed M and F males for mating with (a) virgin ancestral (common) females, (b) virgin females from the M and F populations, and (c) singly mated females from the M and F populations. We also assessed the courtship frequency of the males when paired with mated M or F females. Our results show that M males, evolving under an increased level of male-male competition, have higher mating success than F males irrespective of the female evolutionary history. However, the difference in mating success is more pronounced if the females had mated before. M males also have a higher courtship frequency than F males, but we did not find any correlation between mating success and courtship frequency.
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Affiliation(s)
- Tejinder Singh Chechi
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, 140306, India
| | - Aaditya Narasimhan
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, 140306, India
| | - Broti Biswas
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, 140306, India
| | - Nagaraj Guru Prasad
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, 140306, India
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8
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Singh P, Schärer L. Evolution of sex allocation plasticity in a hermaphroditic flatworm genus. J Evol Biol 2022; 35:817-830. [PMID: 35583959 PMCID: PMC9321609 DOI: 10.1111/jeb.14020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 04/14/2022] [Accepted: 04/25/2022] [Indexed: 11/28/2022]
Abstract
Sex allocation theory in simultaneous hermaphrodites predicts that optimal sex allocation is influenced by local sperm competition, which occurs when related sperm compete to fertilize a given set of eggs. Different factors, including the mating strategy and the ability to self‐fertilize, are predicted to affect local sperm competition and hence the optimal SA. Moreover, since the local sperm competition experienced by an individual can vary temporally and spatially, this can favour the evolution of sex allocation plasticity. Here, using seven species of the free‐living flatworm genus Macrostomum, we document interspecific variation in sex allocation, but neither their mating strategy nor their ability to self‐fertilize significantly predicted sex allocation among these species. Since we also found interspecific variation in sex allocation plasticity, we further estimated standardized effect sizes for plasticity in response to (i) the presence of mating partners (i.e. in isolation vs. with partners) and (ii) the strength of local sperm competition (i.e. in small vs. large groups). We found that self‐fertilization predicted sex allocation plasticity with respect to the presence of mating partners, with plasticity being lower for self‐fertilizing species. Finally, we showed that interspecific variation in sex allocation is higher than intraspecific variation due to sex allocation plasticity. Our study suggests that both sex allocation and sex allocation plasticity are evolutionarily labile, with self‐fertilization predicting the latter in Macrostomum.
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Affiliation(s)
- Pragya Singh
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
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9
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Kasimatis KR, Moerdyk-Schauwecker MJ, Lancaster R, Smith A, Willis JH, Phillips PC. Post-insemination selection dominates pre-insemination selection in driving rapid evolution of male competitive ability. PLoS Genet 2022; 18:e1010063. [PMID: 35157717 PMCID: PMC8880957 DOI: 10.1371/journal.pgen.1010063] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 02/25/2022] [Accepted: 01/28/2022] [Indexed: 11/30/2022] Open
Abstract
Sexual reproduction is a complex process that contributes to differences between the sexes and divergence between species. From a male’s perspective, sexual selection can optimize reproductive success by acting on the variance in mating success (pre-insemination selection) as well as the variance in fertilization success (post-insemination selection). The balance between pre- and post-insemination selection has not yet been investigated using a strong hypothesis-testing framework that directly quantifies the effects of post-insemination selection on the evolution of reproductive success. Here we use experimental evolution of a uniquely engineered genetic system that allows sperm production to be turned off and on in obligate male-female populations of Caenorhabditis elegans. We show that enhanced post-insemination competition increases the efficacy of selection and surpasses pre-insemination sexual selection in driving a polygenic response in male reproductive success. We find that after 10 selective events occurring over 30 generations post-insemination selection increased male reproductive success by an average of 5- to 7-fold. Contrary to expectation, enhanced pre-insemination competition hindered selection and slowed the rate of evolution. Furthermore, we found that post-insemination selection resulted in a strong polygenic response at the whole-genome level. Our results demonstrate that post-insemination sexual selection plays a critical role in the rapid optimization of male reproductive fitness. Therefore, explicit consideration should be given to post-insemination dynamics when considering the population effects of sexual selection. Some of the most dramatic and diverse phenotypes observed in nature––such as head-butting in wild sheep and the elaborate tails of peacocks––are sexually dimorphic. These remarkable phenotypes are a result of sexual selection optimizing reproductive success in females and males independently. For males, total reproductive success is comprised of winning a mating event and then translating that mating event into a fertilization event. Therefore, to understand not only how male reproductive success is comprised, but also how it evolves, we must examine the interaction between pre- and post-insemination sexual selection. We combine environmentally-inducible control of sperm production within a highly reproducible factorial experimental evolution design to directly quantify the contribution of post-insemination selection to male reproductive evolution. We demonstrate that enhanced sperm competition increases the efficacy of selection and enhances the rate of male evolution. Alternatively, we show that enhanced pre-insemination competition slows the evolutionary rate. Using whole-genome approaches, we identify over 60 genes that contribute to male fertilization success. Brought together, our new approaches and results demonstrate that the unseen world of molecular interactions occurring during post-insemination are as fundamentally important as pre-mating factors.
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Affiliation(s)
- Katja R. Kasimatis
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
- * E-mail: (KRK); (PCP)
| | | | - Ruben Lancaster
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
| | - Alexander Smith
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
| | - John H. Willis
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
| | - Patrick C. Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
- * E-mail: (KRK); (PCP)
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10
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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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11
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Fritzsche K, Henshaw JM, Johnson BD, Jones AG. The 150th anniversary of The Descent of Man: Darwin and the impact of sex-role reversal on sexual selection research. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
The year 2021 marks the 150th anniversary of the publication of Charles Darwin’s extraordinary book The Descent of Man and Selection in Relation to Sex. Here, we review the history and impact of a single profound insight from The Descent of Man: that, in some few species, females rather than males compete for access to mates. In other words, these species are ‘sex-role reversed’ with respect to mating competition and sexual selection compared to the majority of species in which sexual selection acts most strongly on males. Over the subsequent 150 years, sex-role-reversed species have motivated multiple key conceptual breakthroughs in sexual selection. The surprising mating dynamics of such species challenged scientists’ preconceptions, forcing them to examine implicit assumptions and stereotypes. This wider worldview has led to a richer and more nuanced understanding of animal mating systems and, in particular, to a proper appreciation for the fundamental role that females play in shaping these systems. Sex-role-reversed species have considerable untapped potential and will continue to contribute to sexual selection research in the decades to come.
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Affiliation(s)
- Karoline Fritzsche
- Institute of Biology I, University of Freiburg, Hauptstraße 1, D-79104 Freiburg, Germany
| | - Jonathan M Henshaw
- Institute of Biology I, University of Freiburg, Hauptstraße 1, D-79104 Freiburg, Germany
| | | | - Adam G Jones
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA
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12
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Greenway EV, Hamel JA, Miller CW. Exploring the effects of extreme polyandry on estimates of sexual selection and reproductive success. Behav Ecol 2021. [DOI: 10.1093/beheco/arab081] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Abstract
Multiple mating by females can dramatically alter selection on males by creating indirect interactions between rivals via sperm competition. Exactly how this behavior alters the relationship between male mating and fertilization success depends on multiple factors: re-mating frequency, sperm usage patterns, and mating assortment (the extent to which the most promiscuous individuals mate with each other). Here, we explore the role these elements play in determining sexual selection in a highly polygyandrous species, the squash bug Anasa tristis. Using replicated semi-natural enclosures, in which individuals were able to freely interact for a 2-week period, we tracked matings between individuals and subsequent female offspring production. Multiple mating was extremely common, resulting in very high levels of sperm competition intensity. However, network analysis revealed that the most promiscuous males mated with less polyandrous females, and therefore experienced lower levels of sperm competition. As a result, estimated male reproductive success increased with mating success, but this relationship varied according to the mode of sperm utilization with which it was calculated. Furthermore, females with more mating partners produced more offspring, suggesting they also benefit from mating multiply. Our findings highlight that polyandry has numerous and complex effects on sexual selection which may only be exposed when examined under naturalistic conditions.
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Affiliation(s)
- E V(Ginny) Greenway
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA
| | - Jennifer A Hamel
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA
- Department of Biology, Elon University, Elon, NC, USA
| | - Christine W Miller
- Entomology and Nematology Department, University of Florida, Gainesville, FL, USA
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13
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Measuring Pre- and Post-Copulatory Sexual Selection and Their Interaction in Socially Monogamous Species with Extra-Pair Paternity. Cells 2021; 10:cells10030620. [PMID: 33799610 PMCID: PMC7999480 DOI: 10.3390/cells10030620] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 01/08/2023] Open
Abstract
When females copulate with multiple males, pre- and post-copulatory sexual selection may interact synergistically or in opposition. Studying this interaction in wild populations is complex and potentially biased, because copulation and fertilization success are often inferred from offspring parentage rather than being directly measured. Here, I simulated 15 species of socially monogamous birds with varying levels of extra-pair paternity, where I could independently cause a male secondary sexual trait to improve copulation success, and a sperm trait to improve fertilization success. By varying the degree of correlation between the male and sperm traits, I show that several common statistical approaches, including univariate selection gradients and paired t-tests comparing extra-pair males to the within-pair males they cuckolded, can give highly biased results for sperm traits. These tests should therefore be avoided for sperm traits in socially monogamous species with extra-pair paternity, unless the sperm trait is known to be uncorrelated with male trait(s) impacting copulation success. In contrast, multivariate selection analysis and a regression of the proportion of extra-pair brood(s) sired on the sperm trait of the extra-pair male (including only broods where the male sired ≥1 extra-pair offspring) were unbiased, and appear likely to be unbiased under a broad range of conditions for this mating system. In addition, I investigated whether the occurrence of pre-copulatory selection impacted the strength of post-copulatory selection, and vice versa. I found no evidence of an interaction under the conditions simulated, where the male trait impacted only copulation success and the sperm trait impacted only fertilization success. Instead, direct selection on each trait was independent of whether the other trait was under selection. Although pre- and post-copulatory selection strength was independent, selection on the two traits was positively correlated across species because selection on both traits increased with the frequency of extra-pair copulations in these socially monogamous species.
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14
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Kasimatis KR, Sánchez-Ramírez S, Stevenson ZC. Sexual Dimorphism through the Lens of Genome Manipulation, Forward Genetics, and Spatiotemporal Sequencing. Genome Biol Evol 2021; 13:evaa243. [PMID: 33587127 PMCID: PMC7883666 DOI: 10.1093/gbe/evaa243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2020] [Indexed: 11/14/2022] Open
Abstract
Sexual reproduction often leads to selection that favors the evolution of sex-limited traits or sex-specific variation for shared traits. These sexual dimorphisms manifest due to sex-specific genetic architectures and sex-biased gene expression across development, yet the molecular mechanisms underlying these patterns are largely unknown. The first step is to understand how sexual dimorphisms arise across the genotype-phenotype-fitness map. The emergence of "4D genome technologies" allows for efficient, high-throughput, and cost-effective manipulation and observations of this process. Studies of sexual dimorphism will benefit from combining these technological advances (e.g., precision genome editing, inducible transgenic systems, and single-cell RNA sequencing) with clever experiments inspired by classic designs (e.g., bulked segregant analysis, experimental evolution, and pedigree tracing). This perspective poses a synthetic view of how manipulative approaches coupled with cutting-edge observational methods and evolutionary theory are poised to uncover the molecular genetic basis of sexual dimorphism with unprecedented resolution. We outline hypothesis-driven experimental paradigms for identifying genetic mechanisms of sexual dimorphism among tissues, across development, and over evolutionary time.
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Affiliation(s)
- Katja R Kasimatis
- Department of Ecology and Evolutionary Biology, University of Toronto, Ontario, USA
| | | | - Zachary C Stevenson
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, USA
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Marie‐Orleach L, Vellnow N, Schärer L. The repeatable opportunity for selection differs between pre- and postcopulatory fitness components. Evol Lett 2021; 5:101-114. [PMID: 33552539 PMCID: PMC7857279 DOI: 10.1002/evl3.210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/21/2020] [Accepted: 11/25/2020] [Indexed: 11/29/2022] Open
Abstract
In species with multiple mating, intense sexual selection may occur both before and after copulation. However, comparing the strength of pre- and postcopulatory selection is challenging, because (i) postcopulatory processes are generally difficult to observe and (ii) the often-used opportunity for selection (I) metric contains both deterministic and stochastic components. Here, we quantified pre- and postcopulatory male fitness components of the simultaneously hermaphroditic flatworm, Macrostomum lignano. We did this by tracking fluorescent sperm-using transgenics-through the transparent body of sperm recipients, enabling to observe postcopulatory processes in vivo. Moreover, we sequentially exposed focal worms to three independent mating groups, and in each assessed their mating success, sperm-transfer efficiency, sperm fertilizing efficiency, and partner fecundity. Based on these multiple measures, we could, for each fitness component, combine the variance (I) with the repeatability (R) in individual success to assess the amount of repeatable variance in individual success-a measure we call the repeatable opportunity for selection (IR ). We found higher repeatable opportunity for selection in sperm-transfer efficiency and sperm fertilizing efficiency compared to mating success, which clearly suggests that postcopulatory selection is stronger than precopulatory selection. Our study demonstrates that the opportunity for selection contains a repeatable deterministic component, which can be assessed and disentangled from the often large stochastic component, to provide a better estimate of the strength of selection.
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Affiliation(s)
- Lucas Marie‐Orleach
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBasel4051Switzerland
- School of Biology, Centre for Biological DiversityUniversity of St AndrewsSt AndrewsKY16 9THUnited Kingdom
- Natural History MuseumUniversity of OsloOslo0318Norway
- CNRS, ECOBIO (Écosystèmes, Biodiversité, Évolution) – UMR 6553Université de Rennes 1Rennes35000France
| | - Nikolas Vellnow
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBasel4051Switzerland
- Evolutionary BiologyBielefeld UniversityBielefeldDE‐33615Germany
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBasel4051Switzerland
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16
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Evans JP, Lymbery RA. Sexual selection after gamete release in broadcast spawning invertebrates. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200069. [PMID: 33070722 DOI: 10.1098/rstb.2020.0069] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Broadcast spawning invertebrates offer highly tractable models for evaluating sperm competition, gamete-level mate choice and sexual conflict. By displaying the ancestral mating strategy of external fertilization, where sexual selection is constrained to act after gamete release, broadcast spawners also offer potential evolutionary insights into the cascade of events that led to sexual reproduction in more 'derived' groups (including humans). Moreover, the dynamic reproductive conditions faced by these animals mean that the strength and direction of sexual selection on both males and females can vary considerably. These attributes make broadcast spawning invertebrate systems uniquely suited to testing, extending, and sometimes challenging classic and contemporary ideas in sperm competition, many of which were first captured in Parker's seminal papers on the topic. Here, we provide a synthesis outlining progress in these fields, and highlight the burgeoning potential for broadcast spawners to provide both evolutionary and mechanistic understanding into gamete-level sexual selection more broadly across the animal kingdom. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia
| | - Rowan A Lymbery
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia
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17
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Henshaw JM, Morrissey MB, Jones AG. Quantifying the causal pathways contributing to natural selection. Evolution 2020; 74:2560-2574. [DOI: 10.1111/evo.14091] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 07/24/2020] [Accepted: 08/07/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Jonathan M. Henshaw
- Institute of Biology I University of Freiburg Freiburg im Breisgau 79104 Germany
- Department of Biological Sciences University of Idaho Moscow Idaho 83844
| | | | - Adam G. Jones
- Department of Biological Sciences University of Idaho Moscow Idaho 83844
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18
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Singh P, Ballmer DN, Laubscher M, Schärer L. Successful mating and hybridisation in two closely related flatworm species despite significant differences in reproductive morphology and behaviour. Sci Rep 2020; 10:12830. [PMID: 32732887 PMCID: PMC7393371 DOI: 10.1038/s41598-020-69767-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/20/2020] [Indexed: 12/16/2022] Open
Abstract
Reproductive traits are some of the fastest diverging characters and can serve as reproductive barriers. The free-living flatworm Macrostomum lignano, and its congener M. janickei are closely related, but differ substantially in their male intromittent organ (stylet) morphology. Here, we examine whether these morphological differences are accompanied by differences in behavioural traits, and whether these could represent barriers to successful mating and hybridization between the two species. Our data shows that the two species differ in many aspects of their mating behaviour. Despite these differences, the species mate readily with each other in heterospecific pairings. Although both species have similar fecundity in conspecific pairings, the heterospecific pairings revealed clear postmating barriers, as few heterospecific pairings produced F1 hybrids. These hybrids had a stylet morphology that was intermediate between that of the parental species, and they were fertile. Finally, using a mate choice experiment, we show that the nearly two-fold higher mating rate of M. lignano caused it to mate more with conspecifics, leading to assortative mating, while M. janickei ended up mating more with heterospecifics. Thus, while the two species can hybridize, the mating rate differences could possibly lead to higher fitness costs for M. janickei compared to M. lignano.
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Affiliation(s)
- Pragya Singh
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland.
| | - Daniel N Ballmer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland.,Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Max Laubscher
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
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19
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Brand JN, Wiberg RAW, Pjeta R, Bertemes P, Beisel C, Ladurner P, Schärer L. RNA-Seq of three free-living flatworm species suggests rapid evolution of reproduction-related genes. BMC Genomics 2020; 21:462. [PMID: 32631219 PMCID: PMC7336406 DOI: 10.1186/s12864-020-06862-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 06/22/2020] [Indexed: 01/03/2023] Open
Abstract
Background The genus Macrostomum consists of small free-living flatworms and contains Macrostomum lignano, which has been used in investigations of ageing, stem cell biology, bioadhesion, karyology, and sexual selection in hermaphrodites. Two types of mating behaviour occur within this genus. Some species, including M. lignano, mate via reciprocal copulation, where, in a single mating, both partners insert their male copulatory organ into the female storage organ and simultaneously donate and receive sperm. Other species mate via hypodermic insemination, where worms use a needle-like copulatory organ to inject sperm into the tissue of the partner. These contrasting mating behaviours are associated with striking differences in sperm and copulatory organ morphology. Here we expand the genomic resources within the genus to representatives of both behaviour types and investigate whether genes vary in their rate of evolution depending on their putative function. Results We present de novo assembled transcriptomes of three Macrostomum species, namely M. hystrix, a close relative of M. lignano that mates via hypodermic insemination, M. spirale, a more distantly related species that mates via reciprocal copulation, and finally M. pusillum, which represents a clade that is only distantly related to the other three species and also mates via hypodermic insemination. We infer 23,764 sets of homologous genes and annotate them using experimental evidence from M. lignano. Across the genus, we identify 521 gene families with conserved patterns of differential expression between juvenile vs. adult worms and 185 gene families with a putative expression in the testes that are restricted to the two reciprocally mating species. Further, we show that homologs of putative reproduction-related genes have a higher protein divergence across the four species than genes lacking such annotations and that they are more difficult to identify across the four species, indicating that these genes evolve more rapidly, while genes involved in neoblast function are more conserved. Conclusions This study improves the genus Macrostomum as a model system, by providing resources for the targeted investigation of gene function in a broad range of species. And we, for the first time, show that reproduction-related genes evolve at an accelerated rate in flatworms.
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Affiliation(s)
- Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland.
| | - R Axel W Wiberg
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| | - Robert Pjeta
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Philip Bertemes
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Christian Beisel
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Peter Ladurner
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
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20
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Cramer ERA, Kaiser SA, Webster MS, Ryder TB. Common Field Data Limitations Can Substantially Bias Sexual Selection Metrics. Am Nat 2020; 196:180-196. [PMID: 32673091 DOI: 10.1086/709547] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Sexual selection studies widely estimate several metrics, but values may be inaccurate because standard field methods for studying wild populations produce limited data (e.g., incomplete sampling, inability to observe copulations directly). We compared four selection metrics (Bateman gradient, opportunity for sexual selection, opportunity for selection, and smax') estimated with simulated complete and simulated limited data for 15 socially monogamous songbird species with extrapair paternity (4%-54% extrapair offspring). Inferring copulation success from offspring parentage creates nonindependence between these variables and systematically underestimates copulation success. We found that this introduces substantial bias for the Bateman gradient, opportunity for sexual selection, and smax'. Notably, 47.5% of detected Bateman gradients were significantly positive for females, suggesting selection on females to copulate with multiple males, although the true Bateman gradient was zero. Bias generally increased with the extent of other sources of data limitations tested (nest predation, male infertility, and unsampled floater males). Incomplete offspring sampling introduced bias for all of the metrics except the Bateman gradient, while incomplete sampling of extrapair sires did not introduce additional bias when sires were a random subset of breeding males. Overall, our findings demonstrate how biases due to field data limitations can strongly impact the study of sexual selection.
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21
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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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22
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Weber M, Patlar B, Ramm SA. Effects of two seminal fluid transcripts on post-mating behaviour in the simultaneously hermaphroditic flatworm Macrostomum lignano. J Evol Biol 2020; 33:714-726. [PMID: 32064699 DOI: 10.1111/jeb.13606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/29/2020] [Accepted: 02/06/2020] [Indexed: 12/12/2022]
Abstract
The seminal fluid proteins (SFPs) transferred to mating partners along with sperm often play crucial roles in mediating post-mating sexual selection. One way in which sperm donors can maximize their own reproductive success is by modifying the partner's (sperm recipient's) post-copulatory behaviour to prevent or delay re-mating, thereby decreasing the likelihood or intensity of sperm competition. Here, we adopted a quantitative genetic approach combining gene expression and behavioural data to identify candidates that could mediate such a response in the simultaneously hermaphroditic flatworm Macrostomum lignano. We identified two putative SFPs-Mlig-pro46 and Mlig-pro63-linked to both mating frequency and 'suck' frequency, a distinctive behaviour, in which, upon ejaculate receipt, the worm places its pharynx over its female genital opening and apparently attempts to remove the received ejaculate. We, therefore, performed a manipulative experiment using RNA interference-induced knockdown to ask how the loss of Mlig-pro46 and Mlig-pro63 expression, singly and in combination, affects mating frequency, partner suck propensity and sperm competitive ability. None of the knockdown treatments impacted strongly on the mating frequency or sperm competitive ability, but knockdown of Mlig-pro63 resulted in a significantly decreased suck propensity of mating partners. This suggests that Mlig-pro63 may normally act as a cue in the ejaculate to trigger recipient suck behaviour and-given that other proteins in the ejaculate have the opposite effect-could be one component of an ongoing arms race between donors and recipients over the control of ejaculate fate. However, the adaptive significance of Mlig-pro46 and Mlig-pro63 from a donor perspective remains enigmatic.
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Affiliation(s)
- Michael Weber
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
| | - Bahar Patlar
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
| | - Steven A Ramm
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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23
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Wudarski J, Egger B, Ramm SA, Schärer L, Ladurner P, Zadesenets KS, Rubtsov NB, Mouton S, Berezikov E. The free-living flatworm Macrostomum lignano. EvoDevo 2020; 11:5. [PMID: 32158530 PMCID: PMC7053086 DOI: 10.1186/s13227-020-00150-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Accepted: 02/12/2020] [Indexed: 01/20/2023] Open
Abstract
Macrostomum lignano is a free-living flatworm that is emerging as an attractive experimental animal for research on a broad range of biological questions. One feature setting it apart from other flatworms is the successful establishment of transgenesis methods, facilitated by a steady supply of eggs in the form of single-cell zygotes that can be readily manipulated. This, in combination with the transparency of the animal and its small size, creates practical advantages for imaging and fluorescence-activated cell sorting in studies related to stem cell biology and regeneration. M. lignano can regenerate most of its body parts, including the germline, thanks to the neoblasts, which represent the flatworm stem cell system. Interestingly, neoblasts seem to have a high capacity of cellular maintenance, as M. lignano can survive up to 210 Gy of γ-irradiation, and partially offset the negative consequence of ageing. As a non-self-fertilizing simultaneous hermaphrodite that reproduces in a sexual manner, M. lignano is also used to study sexual selection and other evolutionary aspects of sexual reproduction. Work over the past several years has led to the development of molecular resources and tools, including high-quality genome and transcriptome assemblies, transcriptional profiling of the germline and somatic neoblasts, gene knockdown, and in situ hybridization. The increasingly detailed characterization of this animal has also resulted in novel research questions, such as bio-adhesion based on its adhesion-release glands and genome evolution due to its recent whole-genome duplication.![]()
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Affiliation(s)
- Jakub Wudarski
- 1European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands
| | - Bernhard Egger
- 2Institute of Zoology and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Steven A Ramm
- 3Department of Evolutionary Biology, Bielefeld University, Morgenbreede 45, 33615 Bielefeld, Germany
| | - Lukas Schärer
- 4Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Peter Ladurner
- 2Institute of Zoology and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Kira S Zadesenets
- 5The Federal Research Center Institute of Cytology and Genetics SB RAS, Prospekt Lavrentyeva 10, Novosibirsk, 630090 Russia
| | - Nikolay B Rubtsov
- 5The Federal Research Center Institute of Cytology and Genetics SB RAS, Prospekt Lavrentyeva 10, Novosibirsk, 630090 Russia
| | - Stijn Mouton
- 1European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands
| | - Eugene Berezikov
- 1European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands.,5The Federal Research Center Institute of Cytology and Genetics SB RAS, Prospekt Lavrentyeva 10, Novosibirsk, 630090 Russia
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Patlar B, Weber M, Temizyürek T, Ramm SA. Seminal Fluid-Mediated Manipulation of Post-mating Behavior in a Simultaneous Hermaphrodite. Curr Biol 2020; 30:143-149.e4. [DOI: 10.1016/j.cub.2019.11.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 09/25/2019] [Accepted: 11/05/2019] [Indexed: 10/25/2022]
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25
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Schärer L, Brand JN, Singh P, Zadesenets KS, Stelzer C, Viktorin G. A phylogenetically informed search for an alternative
Macrostomum
model species, with notes on taxonomy, mating behavior, karyology, and genome size. J ZOOL SYST EVOL RES 2019. [DOI: 10.1111/jzs.12344] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Lukas Schärer
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Jeremias N. Brand
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Pragya Singh
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Kira S. Zadesenets
- The Federal Research Center Institute of Cytology and Genetics SB RAS Novosibirsk Russia
| | | | - Gudrun Viktorin
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
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26
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Weber M, Giannakara A, Ramm SA. Seminal fluid-mediated fitness effects in the simultaneously hermaphroditic flatworm Macrostomum lignano. Ecol Evol 2019; 9:13889-13901. [PMID: 31938489 PMCID: PMC6953679 DOI: 10.1002/ece3.5825] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 11/08/2022] Open
Abstract
As a class, seminal fluid proteins are expected to exert strong effects on mating partners due to the selection pressures of sperm competition and sexual conflict. But because of the complexity of this secretion, linking specific proteins to downstream effects on own fitness-via manipulating the reproductive behavior, physiology, and ultimately the sperm utilization of mating partners-is not straightforward. Here, we adopted a systematic gene knockdown approach to screen for seminal fluid-mediated fitness effects in the simultaneously hermaphroditic flatworm Macrostomum lignano. We focused on 18 transcripts in M. lignano seminal fluid, testing how their RNA interference-induced knockdown impacted on three aspects of donor (male) reproductive success: (a) fertility (offspring production of the partner); (b) defensive sperm competitive ability, P 1; and (c) offensive sperm competitive ability, P 2. In general, the knockdown of most individual transcripts appeared to have only a minor impact on male reproductive success, though we found evidence that the knockdown of up to five different transcripts impacted on fertility; the knockdown of two other transcripts resulted in reduced P 2; and knockdown of a further transcript actually increased P 2. We thus identify a number of candidate seminal fluid transcripts that appear to modulate offspring production and sperm competitiveness in M. lignano. That only a minority of transcripts exhibit such a pattern likely reflects both the difficulty of accurately estimating sperm competitiveness and the functional redundancy of seminal fluid.
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Affiliation(s)
- Michael Weber
- Department of Evolutionary BiologyBielefeld UniversityBielefeldGermany
| | - Athina Giannakara
- Department of Evolutionary BiologyBielefeld UniversityBielefeldGermany
| | - Steven A. Ramm
- Department of Evolutionary BiologyBielefeld UniversityBielefeldGermany
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27
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Patlar B, Ramm SA. Genotype‐by‐environment interactions for seminal fluid expression and sperm competitive ability. J Evol Biol 2019; 33:225-236. [DOI: 10.1111/jeb.13568] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/25/2019] [Accepted: 11/06/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Bahar Patlar
- Evolutionary Biology Bielefeld University Bielefeld Germany
| | - Steven A. Ramm
- Evolutionary Biology Bielefeld University Bielefeld Germany
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28
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Tonnabel J, David P, Pannell JR. Do metrics of sexual selection conform to Bateman's principles in a wind-pollinated plant? Proc Biol Sci 2019; 286:20190532. [PMID: 31213181 PMCID: PMC6599987 DOI: 10.1098/rspb.2019.0532] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Bateman's principles posit that male fitness varies more, and relies more on mate acquisition, than female fitness. While Bateman's principles should apply to any organism producing gametes of variable sizes, their application to plants is potentially complicated by the high levels of polyandry suspected for plants, and by variation in the spatial distribution of prospective mates. Here we quantify the intensity of sexual selection by classical Bateman metrics using two common gardens of the wind-pollinated dioecious plant Mercurialis annua. Consistent with Bateman's principles, males displayed significantly positive Bateman gradients (a regression of fitness on mate number), whereas the reproductive success of females was independent of their ability to access mates. A large part of male fitness was explained by their mate number, which in turn was associated with males' abilities to disperse pollen. Our results suggest that sexual selection can act in plant species in much the same way as in many animals, increasing the number of mates through traits that promote pollen dispersal.
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Affiliation(s)
- Jeanne Tonnabel
- 1 Department of Ecology and Evolution, University of Lausanne , CH-1015 Lausanne , Switzerland
| | - Patrice David
- 2 Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS, UM, Université Paul Valéry Montpellier, EPHE , 1919 route de Mende, 34293 Montpellier Cedex 5 , France
| | - John R Pannell
- 1 Department of Ecology and Evolution, University of Lausanne , CH-1015 Lausanne , Switzerland
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29
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Mouton S, Wudarski J, Grudniewska M, Berezikov E. The regenerative flatworm Macrostomum lignano, a model organism with high experimental potential. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2019; 62:551-558. [PMID: 29938766 DOI: 10.1387/ijdb.180077eb] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Understanding the process of regeneration has been one of the longstanding scientific aims, from a fundamental biological perspective, as well as within the applied context of regenerative medicine. Because regeneration competence varies greatly between organisms, it is essential to investigate different experimental animals. The free-living marine flatworm Macrostomum lignano is a rising model organism for this type of research, and its power stems from a unique set of biological properties combined with amenability to experimental manipulation. The biological properties of interest include production of single-cell fertilized eggs, a transparent body, small size, short generation time, ease of culture, the presence of a pluripotent stem cell population, and a large regeneration competence. These features sparked the development of molecular tools and resources for this animal, including high-quality genome and transcriptome assemblies, gene knockdown, in situ hybridization, and transgenesis. Importantly, M. lignano is currently the only flatworm species for which transgenesis methods are established. This review summarizes biological features of M. lignano and recent technological advances towards experimentation with this animal. In addition, we discuss the experimental potential of this model organism for different research questions related to regeneration and stem cell biology.
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Affiliation(s)
- Stijn Mouton
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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30
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Janicke T, Ritchie MG, Morrow EH, Marie-Orleach L. Sexual selection predicts species richness across the animal kingdom. Proc Biol Sci 2019; 285:rspb.2018.0173. [PMID: 29720412 DOI: 10.1098/rspb.2018.0173] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/10/2018] [Indexed: 12/13/2022] Open
Abstract
Our improving knowledge of the animal tree of life consistently demonstrates that some taxa diversify more rapidly than others, but what contributes to this variation remains poorly understood. An influential hypothesis proposes that selection arising from competition for mating partners plays a key role in promoting speciation. However, empirical evidence showing a link between proxies of this sexual selection and species richness is equivocal. Here, we collected standardized metrics of sexual selection for a broad range of animal taxa, and found that taxonomic families characterized by stronger sexual selection on males show relatively higher species richness. Thus, our data support the hypothesis that sexual selection elevates species richness. This could occur either by promoting speciation and/or by protecting species against extinction.
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Affiliation(s)
- Tim Janicke
- Evolution, Behaviour and Environment Group, School of Life Sciences, University of Sussex, Brighton, UK.,Centre d'Écologie Fonctionnelle et Évolutive, UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, École Pratique des Hautes Études, 34090 Montpellier, France
| | - Michael G Ritchie
- Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews, UK
| | - Edward H Morrow
- Evolution, Behaviour and Environment Group, School of Life Sciences, University of Sussex, Brighton, UK
| | - Lucas Marie-Orleach
- Centre for Biological Diversity, School of Biology, University of St Andrews, St Andrews, UK
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31
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Cai YL, Mai CL, Yu X, Liao WB. Effect of population density on relationship between pre- and postcopulatory sexual traits. ANIM BIOL 2019. [DOI: 10.1163/15707563-20181057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Sexual selection theory states that the premating (ornaments and armaments) sexual traits should trade off with the postmating (testes and ejaculates) sexual traits, assuming that growing and maintaining these traits is expensive and that total reproductive investments are limited. Male-male competition and sperm competition are predicted to affect how males allocate their finite resources to these traits. Here, we studied relative expenditure on pre- and postmating sexual traits among 82 species for three mammalian orders with varying population density using comparative phylogenetic analysis. The results showed that population density affected sexual size dimorphism (SSD) in both Artiodactyla and Carnivora, but not in Primates. However, relative testis mass and sperm size were not affected by population density. Moreover, we did not find associations between the SSD and testis mass or sperm size in three taxonomic groups. The interspecific relationships between pre- and postcopulatory sexual traits did not change with increased population density. Our findings suggest that population density did not affect variation in the relationship between pre- and postcopulatory sexual traits for these three mammalian orders.
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Affiliation(s)
- Yun Lin Cai
- 1Department of Urology, the Second Clinical Medical College of North Sichuan Medical College, Nanchong, 637000, China
| | - Chun Lan Mai
- 2Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, China
| | - Xin Yu
- 2Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, China
| | - Wen Bo Liao
- 2Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, China
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32
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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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33
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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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34
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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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35
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Weber M, Wunderer J, Lengerer B, Pjeta R, Rodrigues M, Schärer L, Ladurner P, Ramm SA. A targeted in situ hybridization screen identifies putative seminal fluid proteins in a simultaneously hermaphroditic flatworm. BMC Evol Biol 2018; 18:81. [PMID: 29848299 PMCID: PMC5977470 DOI: 10.1186/s12862-018-1187-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/30/2018] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Along with sperm, in many taxa ejaculates also contain large numbers of seminal fluid proteins (SFPs). SFPs and sperm are transferred to the mating partner, where they are thought to play key roles in mediating post-mating sexual selection. They modulate the partner's behavior and physiology in ways that influence the reproductive success of both partners, thus potentially leading to sexual conflict. Despite the presumed general functional and evolutionary significance of SFPs, their identification and characterization has to date focused on just a few animal groups, predominantly insects and mammals. Moreover, until now seminal fluid profiling has mainly focused on species with separate sexes. Here we report a comprehensive screen for putative SFPs in the simultaneously hermaphroditic flatworm Macrostomum lignano. RESULTS Based on existing transcriptomic data, we selected 150 transcripts known to be (a) predominantly expressed in the tail region of the worms, where the seminal fluid-producing prostate gland cells are located, and (b) differentially expressed in social environments differing in sperm competition level, strongly implying that they represent a phenotypically plastic aspect of male reproductive allocation in this species. For these SFP candidates, we then performed whole-mount in situ hybridization (ISH) experiments to characterize tissue-specific expression. In total, we identified 98 transcripts that exhibited prostate-specific expression, 76 of which we found to be expressed exclusively in the prostate gland cells; additional sites of expression for the remaining 22 included the testis or other gland cells. Bioinformatics analyses of the prostate-limited candidates revealed that at least 64 are predicted to be secretory proteins, making these especially strong candidates to be SFPs that are transferred during copulation. CONCLUSIONS Our study represents a first comprehensive analysis using a combination of transcriptomic and ISH screen data to identify SFPs based on transcript expression in seminal fluid-producing tissues. We thereby extend the range of taxa for which seminal fluid has been characterized to a flatworm species with a sequenced genome and for which several methods such as antibody staining, transgenesis and RNA interference have been established. Our data provide a basis for testing the functional and evolutionary significance of SFPs.
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Affiliation(s)
- Michael Weber
- Evolutionary Biology, Bielefeld University, Konsequenz 45, 33615 Bielefeld, Germany
| | - Julia Wunderer
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Birgit Lengerer
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Robert Pjeta
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Marcelo Rodrigues
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
- Current address: School of Natural and Environmental Sciences, Ridley Building, Newcastle University, Newcastle upon Tyne, England NE1 7RU UK
| | - Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Peter Ladurner
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Steven A. Ramm
- Evolutionary Biology, Bielefeld University, Konsequenz 45, 33615 Bielefeld, Germany
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36
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McCullough EL, Buzatto BA, Simmons LW. Population density mediates the interaction between pre‐ and postmating sexual selection. Evolution 2018; 72:893-905. [DOI: 10.1111/evo.13455] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 01/04/2018] [Accepted: 02/02/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Erin L. McCullough
- Centre for Evolutionary Biology, School of Biological Sciences (M092) The University of Western Australia Crawley Western Australia 6009 Australia
| | - Bruno A. Buzatto
- Centre for Evolutionary Biology, School of Biological Sciences (M092) The University of Western Australia Crawley Western Australia 6009 Australia
| | - Leigh W. Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092) The University of Western Australia Crawley Western Australia 6009 Australia
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37
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Cattelan S, Di Nisio A, Pilastro A. Stabilizing selection on sperm number revealed by artificial selection and experimental evolution. Evolution 2018; 72:698-706. [PMID: 29337356 DOI: 10.1111/evo.13425] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 12/25/2017] [Indexed: 01/01/2023]
Abstract
Sperm competition is taxonomically widespread in animals and is usually associated with large sperm production, being the number of sperm in the competing pool the prime predictor of fertilization success. Despite the strong postcopulatory selection acting directionally on sperm production, its genetic variance is often very high. This can be explained by trade-offs between sperm production and traits associated with mate acquisition or survival, that may contribute to generate an overall stabilizing selection. To investigate this hypothesis, we first artificially selected male guppies (Poecilia reticulata) for high and low sperm production for three generations, while simultaneously removing sexual selection. Then, we interrupted artificial selection and restored sexual selection. Sperm production responded to divergent selection in one generation, and when we restored sexual selection, both high and low lines converged back to the mean sperm production of the original population within two generations, indicating that sperm number is subject to strong stabilizing total sexual selection (i.e., selection acting simultaneously on all traits associated with reproductive success). We discuss the possible mechanisms responsible for the maintenance of high genetic variability in sperm production despite strong selection acting on it.
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Affiliation(s)
| | - Andrea Di Nisio
- Department of Biology, University of Padova, Padova, Italy.,Current Address: Department of Medicine, University of Padova, Padova, Italy
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38
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Janicke T, Morrow EH. Operational sex ratio predicts the opportunity and direction of sexual selection across animals. Ecol Lett 2018; 21:384-391. [PMID: 29341415 DOI: 10.1111/ele.12907] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/11/2017] [Accepted: 12/11/2017] [Indexed: 12/17/2022]
Abstract
The operational sex ratio (OSR) has long been assumed to be a key ecological factor determining the opportunity and direction of sexual selection. However, recent theoretical work has challenged this view, arguing that a biased OSR does not necessarily result in greater monopolisation of mates and therefore stronger sexual selection in the mate-limited sex. Hence, the role of the OSR for shaping animal mating systems remains a conundrum in sexual selection research. Here we took a meta-analytic approach to test whether OSR explains interspecific variation in sexual selection metrics across a broad range of animal taxa. Our results demonstrate that the OSR predicts the opportunity for sexual selection in males and the direction of sexual selection in terms of sex differences in both the opportunity for sexual selection and the Bateman gradient (i.e. the selection differential of mating success), as predicted by classic theory.
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Affiliation(s)
- Tim Janicke
- Ecology, Behaviour and Environment Group, University of Sussex, Brighton, UK.,Centre d'Écologie Fonctionnelle et Évolutive, UMR 5175, CNRS, Université de Montpellier, École Pratique des Hautes Études, Montpellier, France
| | - Edward H Morrow
- Ecology, Behaviour and Environment Group, University of Sussex, Brighton, UK
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39
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Efficient transgenesis and annotated genome sequence of the regenerative flatworm model Macrostomum lignano. Nat Commun 2017; 8:2120. [PMID: 29242515 PMCID: PMC5730564 DOI: 10.1038/s41467-017-02214-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 11/12/2017] [Indexed: 01/15/2023] Open
Abstract
Regeneration-capable flatworms are informative research models to study the mechanisms of stem cell regulation, regeneration, and tissue patterning. However, the lack of transgenesis methods considerably hampers their wider use. Here we report development of a transgenesis method for Macrostomum lignano, a basal flatworm with excellent regeneration capacity. We demonstrate that microinjection of DNA constructs into fertilized one-cell stage eggs, followed by a low dose of irradiation, frequently results in random integration of the transgene in the genome and its stable transmission through the germline. To facilitate selection of promoter regions for transgenic reporters, we assembled and annotated the M. lignano genome, including genome-wide mapping of transcription start regions, and show its utility by generating multiple stable transgenic lines expressing fluorescent proteins under several tissue-specific promoters. The reported transgenesis method and annotated genome sequence will permit sophisticated genetic studies on stem cells and regeneration using M. lignano as a model organism. Regeneration capable flatworms have emerged as powerful models for studying stem cell biology and patterning, however their study has been hindered by the lack of transgenesis methods. Here, the authors describe a transgenesis method for Macrostomum lignano, as well as a new annotated genome sequence.
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40
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Vellnow N, Marie-Orleach L, Zadesenets KS, Schärer L. Bigger testes increase paternity in a simultaneous hermaphrodite, independently of the sperm competition level. J Evol Biol 2017; 31:180-196. [DOI: 10.1111/jeb.13212] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 10/31/2017] [Accepted: 11/14/2017] [Indexed: 12/12/2022]
Affiliation(s)
- N. Vellnow
- Zoological Institute, Evolutionary Biology; University of Basel; Basel Switzerland
| | | | | | - L. Schärer
- Zoological Institute, Evolutionary Biology; University of Basel; Basel Switzerland
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41
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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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42
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McDiarmid CS, Friesen CR, Ballen C, Olsson M. Sexual coloration and sperm performance in the Australian painted dragon lizard,
Ctenophorus pictus. J Evol Biol 2017; 30:1303-1312. [DOI: 10.1111/jeb.13092] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/12/2017] [Indexed: 12/16/2022]
Affiliation(s)
- C. S. McDiarmid
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - C. R. Friesen
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - C. Ballen
- College of Biological Sciences University of Minnesota Minneapolis MN USA
| | - M. Olsson
- Department of Biological and Environmental Sciences Göteborg University Göteborg Sweden
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43
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Lüpold S, Jin L, Liao WB. Population density and structure drive differential investment in pre- and postmating sexual traits in frogs. Evolution 2017; 71:1686-1699. [PMID: 28394412 DOI: 10.1111/evo.13246] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 03/25/2017] [Indexed: 01/01/2023]
Abstract
Sexual selection theory predicts a trade-off between premating (ornaments and armaments) and postmating (testes and ejaculates) sexual traits, assuming that growing and maintaining these traits is costly and that total reproductive investments are limited. The number of males in competition, the reproductive gains from investing in premating sexual traits, and the level of sperm competition are all predicted to influence how males allocate their finite resources to these traits. Yet, empirical examination of these predictions is currently scarce. Here, we studied relative expenditure on pre- and postmating sexual traits among frog species varying in their population density, operational sex ratio, and the number of competing males for each clutch of eggs. We found that the intensifying struggle to monopolize fertilizations as more and more males clasp the same female to fertilize her eggs shifts male reproductive investment toward sperm production and away from male weaponry. This shift, which is mediated by population density and the associated level of male-male competition, likely also explains the trade-off between pre- and postmating sexual traits in our much broader sample of anuran species. Our results highlight the power of such a multilevel approach in resolving the evolution of traits and allocation trade-offs.
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Affiliation(s)
- Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Long Jin
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, P. R. China
| | - Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, P. R. China
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44
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Vellnow N, Vizoso DB, Viktorin G, Schärer L. No evidence for strong cytonuclear conflict over sex allocation in a simultaneously hermaphroditic flatworm. BMC Evol Biol 2017; 17:103. [PMID: 28427326 PMCID: PMC5397761 DOI: 10.1186/s12862-017-0952-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 04/10/2017] [Indexed: 01/31/2023] Open
Abstract
Background Cytoplasmic sex allocation distorters, which arise from cytonuclear conflict over the optimal investment into male versus female reproductive function, are some of the best-researched examples for genomic conflict. Among hermaphrodites, many such distorters have been found in plants, while, to our knowledge, none have been clearly documented in animals. Methods Here we provide a quantitative test for cytonuclear conflict over sex allocation in the simultaneously hermaphroditic flatworm Macrostomum lignano. We used a quantitative genetic breeding design, employing pair-wise crosses of 2 × 15 independent inbred lines, to partition the phenotypic variance in several traits (including sex allocation) into its nuclear and cytoplasmic components. Results Although the nuclear genetic background had a significant effect on all traits analyzed, we found significant cytoplasmic genetic variation only for ovary size, there explaining just 4.1% of the variance. A subsequent statistical power analysis showed that the experimental design had considerable power to detect cytonuclear interactions. Conclusion We conclude that there were no strong effects of cytonuclear conflict in the studied populations, possibly because the usually compact mitochondrial genomes in animals have a lower evolvability than the large mitochondrial genomes in plants or because the sampled populations currently do not harbor variation at putative distorter and/or the restorer loci. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-0952-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nikolas Vellnow
- University of Basel, Zoological Institute, Evolutionary Biology, Basel, Switzerland.
| | - Dita B Vizoso
- University of Basel, Zoological Institute, Evolutionary Biology, Basel, Switzerland.,University of Innsbruck, Institute of Zoology, Innsbruck, Austria
| | - Gudrun Viktorin
- University of Basel, Zoological Institute, Evolutionary Biology, Basel, Switzerland
| | - Lukas Schärer
- University of Basel, Zoological Institute, Evolutionary Biology, Basel, Switzerland.,University of Innsbruck, Institute of Zoology, Innsbruck, Austria
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45
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Marie-Orleach L, Vogt-Burri N, Mouginot P, Schlatter A, Vizoso DB, Bailey NW, Schärer L. Indirect genetic effects and sexual conflicts: Partner genotype influences multiple morphological and behavioral reproductive traits in a flatworm. Evolution 2017; 71:1232-1245. [PMID: 28252800 DOI: 10.1111/evo.13218] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/14/2017] [Accepted: 02/26/2017] [Indexed: 01/07/2023]
Abstract
The expression of an individual's phenotypic traits can be influenced by genes expressed in its social partners. Theoretical models predict that such indirect genetic effects (IGEs) on reproductive traits should play an important role in determining the evolutionary outcome of sexual conflict. However, empirical tests of (i) whether reproductive IGEs exist, (ii) how they vary among genotypes, and (iii) whether they are uniform for different types of reproductive traits are largely lacking. We addressed this in a series of experiments in the simultaneously hermaphroditic flatworm Macrostomum lignano. We found strong evidence for IGEs on both morphological and behavioral reproductive traits. Partner genotype had a significant impact on the testis size of focal individuals-varying up to 2.4-fold-suggesting that IGEs could mediate sexual conflicts that target the male sex function. We also found that time to first copulation was affected by a genotype × genotype interaction between mating partners, and that partner genotype affected the propensity to copulate and perform the postcopulatory suck behavior, which may mediate conflicts over the fate of received ejaculate components. These findings provide clear empirical evidence for IGEs on multiple behavioral and morphological reproductive traits, which suggests that the evolutionary dynamics of these traits could be altered by genes contained in the social environment.
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Affiliation(s)
- Lucas Marie-Orleach
- Evolutionary Biology, Zoological Institute, University of Basel, Switzerland.,Centre for Biological Diversity, School of Biology, University of St. Andrews, United Kingdom
| | - Nadja Vogt-Burri
- Evolutionary Biology, Zoological Institute, University of Basel, Switzerland
| | - Pierick Mouginot
- Evolutionary Biology, Zoological Institute, University of Basel, Switzerland.,General and Systematic Zoology, Museum and Zoological Institute, Ernst Moritz Arndt University of Greifswald, Greifswald, Germany
| | - Aline Schlatter
- Evolutionary Biology, Zoological Institute, University of Basel, Switzerland
| | - Dita B Vizoso
- Evolutionary Biology, Zoological Institute, University of Basel, Switzerland
| | - Nathan W Bailey
- Centre for Biological Diversity, School of Biology, University of St. Andrews, United Kingdom
| | - Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Switzerland
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46
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Giannakara A, Ramm SA. Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically inseminating flatworm Macrostomum pusillum. ACTA ACUST UNITED AC 2017; 220:1568-1577. [PMID: 28183866 DOI: 10.1242/jeb.149682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 02/03/2017] [Indexed: 01/15/2023]
Abstract
The free-living flatworm genus Macrostomum is an emerging model system for studying the links between sex allocation, sexual selection and mating system evolution, as well as the underlying developmental and physiological mechanisms responsible for wide intra- and inter-specific variability in reproductive phenotypes. Despite compelling comparative morphological evidence of sexual diversity, detailed experimental work on reproductive behaviour and physiology in Macrostomum has so far been largely limited to just two species, M. lignano and M. hystrix, an obligate and a preferential outcrosser, respectively. In this study, we establish that a third species, M. pusillum, exhibits a combination of reproductive traits strikingly different from both of its congeners. Unlike M. lignano, we demonstrate that M. pusillum does not adjust sex allocation or the speed of spermatogenesis to the prevailing social group size. Macrostomumpusillum's relatively simple sperm morphology likely explains the short spermatogenesis duration we report, and is linked to a hypodermically inseminating mode of fertilization, which we show also means that these worms are capable of self-fertilization. Surprisingly, and unlike M. hystrix, selfing in isolated worms commences after only a short (if any) delay compared with the onset of reproduction in grouped individuals, with little evidence of differential inbreeding depression in 'isolated' progeny. These combined results suggest that, in nature, M. pusillum may be regularly selfing, in contrast to the congeners studied to date. Our findings highlight the rapid and correlated evolution of reproductive traits, and reinforce the utility of the genus Macrostomum for understanding the evolutionary and developmental mechanisms responsible for this diversity.
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Affiliation(s)
- Athina Giannakara
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
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47
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Grudniewska M, Mouton S, Simanov D, Beltman F, Grelling M, de Mulder K, Arindrarto W, Weissert PM, van der Elst S, Berezikov E. Transcriptional signatures of somatic neoblasts and germline cells in Macrostomum lignano. eLife 2016; 5. [PMID: 27997336 PMCID: PMC5173321 DOI: 10.7554/elife.20607] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Accepted: 12/01/2016] [Indexed: 12/11/2022] Open
Abstract
The regeneration-capable flatworm Macrostomum lignano is a powerful model organism to study the biology of stem cells in vivo. As a flatworm amenable to transgenesis, it complements the historically used planarian flatworm models, such as Schmidtea mediterranea. However, information on the transcriptome and markers of stem cells in M. lignano is limited. We generated a de novo transcriptome assembly and performed the first comprehensive characterization of gene expression in the proliferating cells of M. lignano, represented by somatic stem cells, called neoblasts, and germline cells. Knockdown of a selected set of neoblast genes, including Mlig-ddx39, Mlig-rrm1, Mlig-rpa3, Mlig-cdk1, and Mlig-h2a, confirmed their crucial role for the functionality of somatic neoblasts during homeostasis and regeneration. The generated M. lignano transcriptome assembly and gene expression signatures of somatic neoblasts and germline cells will be a valuable resource for future molecular studies in M. lignano. DOI:http://dx.doi.org/10.7554/eLife.20607.001
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Affiliation(s)
- Magda Grudniewska
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Stijn Mouton
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Hubrecht Institute-KNAW, Utrecht, The Netherlands.,University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Daniil Simanov
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Hubrecht Institute-KNAW, Utrecht, The Netherlands.,University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Frank Beltman
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Margriet Grelling
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Katrien de Mulder
- Hubrecht Institute-KNAW, Utrecht, The Netherlands.,University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Wibowo Arindrarto
- Hubrecht Institute-KNAW, Utrecht, The Netherlands.,University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Philipp M Weissert
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Stefan van der Elst
- Hubrecht Institute-KNAW, Utrecht, The Netherlands.,University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Eugene Berezikov
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Hubrecht Institute-KNAW, Utrecht, The Netherlands.,University Medical Centre Utrecht, Utrecht, The Netherlands
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48
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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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49
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Evans JP, Garcia-Gonzalez F. The total opportunity for sexual selection and the integration of pre- and post-mating episodes of sexual selection in a complex world. J Evol Biol 2016; 29:2338-2361. [PMID: 27520979 DOI: 10.1111/jeb.12960] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 08/05/2016] [Accepted: 08/05/2016] [Indexed: 12/30/2022]
Abstract
It is well known that sexual selection can target reproductive traits during successive pre- and post-mating episodes of selection. A key focus of recent studies has been to understand and quantify how these episodes of sexual selection interact to determine overall variance in reproductive success. In this article, we review empirical developments in this field but also highlight the considerable variability in patterns of pre- and post-mating sexual selection, attributable to variation in patterns of resource acquisition and allocation, ecological and social factors, genotype-by-environment interaction and possible methodological factors that might obscure such patterns. Our aim is to highlight how (co)variances in pre- and post-mating sexually selected traits can be sensitive to changes in a range of ecological and environmental variables. We argue that failure to capture this variation when quantifying the opportunity for sexual selection may lead to erroneous conclusions about the strength, direction or form of sexual selection operating on pre- and post-mating traits. Overall, we advocate for approaches that combine measures of pre- and post-mating selection across contrasting environmental or ecological gradients to better understand the dynamics of sexual selection in polyandrous species. We also discuss some directions for future research in this area.
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Affiliation(s)
- J P Evans
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia
| | - F Garcia-Gonzalez
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia.,Doñana Biological Station, Spanish Research Council CSIC, Sevilla, Spain
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50
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Ramm SA. Exploring the sexual diversity of flatworms: Ecology, evolution, and the molecular biology of reproduction. Mol Reprod Dev 2016; 84:120-131. [PMID: 27292123 DOI: 10.1002/mrd.22669] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 06/01/2016] [Indexed: 12/12/2022]
Abstract
Flatworms exhibit huge diversity in their reproductive biology, making this group an excellent model system for exploring how differences among species in reproductive ecology are reflected in the physiological and molecular details of how reproduction is achieved. In this review, I consider five key "lifestyle choices" (i.e., alternative evolutionary/developmental outcomes) that collectively encompass much of flatworm sexual diversity, beginning with the decisions: (i) whether to be free-living or parasitic; (ii) whether to reproduce asexually or sexually; and (iii) whether to be gonochoristic (separate-sexed) or hermaphroditic. I then examine two further decisions involving hermaphroditism: (iv) outcrossing versus selfing and (v) the balance of investment into the male versus the female sex function (sex allocation). Collectively, these lifestyle choices set the basic rules for how reproduction occurs, but as I emphasize in the second part of the review, the reproductive biology of flatworms is also greatly impacted by the near-pervasive and powerful pressure of sexual selection, together with the related phenomena of sperm competition and sexual conflict. Exactly how this plays out, however, is strongly affected by the particular combination of reproductive strategies adopted by each species. Mol. Reprod. Dev. 84: 120-131, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Steven A Ramm
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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