1
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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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2
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Cīrulis A, Nordén AK, Churcher AM, Ramm SA, Zadesenets KS, Abbott JK. Sex-limited experimental evolution drives transcriptomic divergence in a hermaphrodite. Genome Biol Evol 2024; 16:evad235. [PMID: 38155579 PMCID: PMC10786194 DOI: 10.1093/gbe/evad235] [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: 02/22/2023] [Revised: 12/12/2023] [Accepted: 12/23/2023] [Indexed: 12/30/2023] Open
Abstract
The evolution of gonochorism from hermaphroditism is linked with the formation of sex chromosomes, as well as the evolution of sex-biased and sex-specific gene expression to allow both sexes to reach their fitness optimum. There is evidence that sexual selection drives the evolution of male-biased gene expression in particular. However, previous research in this area in animals comes from either theoretical models or comparative studies of already old sex chromosomes. We therefore investigated changes in gene expression under 3 different selection regimes for the simultaneous hermaphrodite Macrostomum lignano subjected to sex-limited experimental evolution (i.e. selection for fitness via eggs, sperm, or a control regime allowing both). After 21 and 22 generations of selection for male-specific or female-specific fitness, we characterized changes in whole-organism gene expression. We found that female-selected lines had changed the most in their gene expression. Although annotation for this species is limited, gene ontology term and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggest that metabolic changes (e.g. biosynthesis of amino acids and carbon metabolism) are an important adaptive component. As predicted, we found that the expression of genes previously identified as testis-biased candidates tended to be downregulated in the female-selected lines. We did not find any significant expression differences for previously identified candidates of other sex-specific organs, but this may simply reflect that few transcripts have been characterized in this way. In conclusion, our experiment suggests that changes in testis-biased gene expression are important in the early evolution of sex chromosomes and gonochorism.
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Affiliation(s)
- Aivars Cīrulis
- Department of Biology, Lund University, 223 62 Lund, Sweden
- Laboratory of Microbiology and Pathology, Institute of Food Safety, Animal Health and Environment “BIOR,”Riga LV-1076, Latvia
- Faculty of Biology, University of Latvia, Riga LV-1004, Latvia
| | - Anna K Nordén
- Department of Biology, Lund University, 223 62 Lund, Sweden
| | - Allison M Churcher
- Department of Molecular Biology, National Bioinformatics Infrastructure Sweden, Umeå University, 901 87 Umeå, Sweden
| | - Steven A Ramm
- Department of Evolutionary Biology, Bielefeld University, 33615 Bielefeld, Germany
- UMR 6553 ECOBIO, Université de Rennes, 35042 Rennes, France
| | - Kira S Zadesenets
- Department of Molecular Genetics, Cell Biology and Bionformatics, The Federal Research Center Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russian Federation
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3
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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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4
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Brannelly LA, Webb RJ, Jiang Z, Berger L, Skerratt LF, Grogan LF. Declining amphibians might be evolving increased reproductive effort in the face of devastating disease. Evolution 2021; 75:2555-2567. [PMID: 34383313 DOI: 10.1111/evo.14327] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 07/08/2021] [Accepted: 07/20/2021] [Indexed: 12/12/2022]
Abstract
The devastating infectious disease chytridiomycosis has caused declines of amphibians across the globe, yet some populations are persisting and even recovering. One understudied effect of wildlife disease is changes in reproductive effort. Here, we aimed to understand if the disease has plastic effects on reproduction and if reproductive effort could evolve with disease endemism. We compared the effects of experimental pathogen exposure (trait plasticity) and population-level disease history (evolution in trait baseline) on reproductive effort using gametogenesis as a proxy in the declining and endangered frog Litoria verreauxii alpina. We found that unexposed males from disease-endemic populations had higher reproductive effort, which is consistent with an evolutionary response to chytridiomycosis. We also found evidence of trait plasticity, where males and females were affected differently by infection: pathogen exposed males had higher reproductive effort (larger testes), whereas females had reduced reproductive effort (smaller and fewer developed eggs) regardless of the population of origin. Infectious diseases can cause plastic changes in the reproductive effort at an individual level, and population-level disease exposure can result in changes to baseline reproductive effort; therefore, individual- and population-level effects of disease should be considered when designing management and conservation programs for threatened and declining species.
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Affiliation(s)
- Laura A Brannelly
- One Health Research Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Rebecca J Webb
- One Health Research Group, School of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | - Zhixuan Jiang
- One Health Research Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Lee Berger
- One Health Research Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Lee F Skerratt
- One Health Research Group, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Laura F Grogan
- Environmental Futures Research Institute, Griffith University, Southport, Queensland, Australia.,Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
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5
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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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6
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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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7
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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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8
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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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9
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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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10
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Monteiro LR, Mellado B, Nogueira MR, de Morais-Jr MM. Individual asymmetry as a predictor of fitness in the bat Carollia perspicillata. J Evol Biol 2019; 32:1207-1229. [PMID: 31420901 DOI: 10.1111/jeb.13522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 07/08/2019] [Accepted: 08/09/2019] [Indexed: 11/26/2022]
Abstract
The measurement of fitness in wild populations is a challenging task, and a number of proxies have been proposed with different degrees of success. Developmental instability/stability (DI) is an organismal property associated with variance in bilateral asymmetry (fluctuating asymmetry-FA) and a correlated effect on fitness. This study provides evidence to corroborate the hypothesis that asymmetry partly reflects DI and is correlated with a reduction in fitness measured by survival and reproduction in bats. We studied two colonies of the bat Carollia perspicillata in southeastern Brazil over 5 years, marking and recapturing individuals. Gaussian mixture models for signed Forearm Asymmetry (ForA) distribution indicated that ~20% of asymmetry variation was due to DI heterogeneity among individuals. ForA, body condition (Scaled Mass Index-SMI) and Forearm Length (ForL) were used as predictors of survival probability in Cormack-Jolly-Seber models. Asymmetry was negatively associated with survival, whereas SMI and ForL were positively associated. The male C. perspicillata defend sites within the roost that are favoured by female harems, but there are mating opportunities for bachelor males, leading to both territorial disputes and sperm competition. As predicted by sexual selection, ForA was negatively associated with relative Testicle Length, a measure of reproductive potential. In females, ForA was negatively associated with the probability of two pregnancies (as opposed to one) in a given breeding season. The effect magnitudes and directions of associations suggest that asymmetry, even though not perfectly reflecting DI variation, is a useful predictor for fitness components in C. perspicillata.
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Affiliation(s)
- Leandro R Monteiro
- Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ, Brazil
| | - Breno Mellado
- Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ, Brazil
| | - Marcelo R Nogueira
- Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ, Brazil
| | - Marcio M de Morais-Jr
- Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ, Brazil
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11
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Macartney EL, Crean AJ, Nakagawa S, Bonduriansky R. Effects of nutrient limitation on sperm and seminal fluid: a systematic review and meta-analysis. Biol Rev Camb Philos Soc 2019; 94:1722-1739. [PMID: 31215758 DOI: 10.1111/brv.12524] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 01/05/2023]
Abstract
Theory predicts that costly sexual traits should be reduced when individuals are in poor condition (i.e. traits should exhibit condition-dependent expression). It is therefore widely expected that male ejaculate traits, such as sperm and seminal fluid, will exhibit reduced quantity and quality when dietary nutrients are limited. However, reported patterns of ejaculate condition dependence are highly variable, and there has been no comprehensive synthesis of underlying sources of such variation in condition-dependent responses. In particular, it remains unclear whether all ejaculate traits are equally sensitive to nutrient intake, and whether such traits are particularly sensitive to certain dietary nutrients, respond more strongly to nutrients during specific life stages, or respond more strongly in some taxonomic groups. We systematically reviewed these potential sources of variation through a meta-analysis across 50 species of arthropods and vertebrates (from 71 papers and 348 effect sizes). We found that overall, ejaculate traits are moderately reduced when dietary nutrients are limited, but we also detected substantial variation in responses. Seminal fluid quantity was strongly and consistently condition dependent, while sperm quantity was moderately condition dependent. By contrast, aspects of sperm quality (particularly sperm viability and morphology) were less consistently reduced under nutrient limitation. Ejaculate traits tended to respond in a condition-dependent manner to a wide range of dietary manipulations, especially to caloric and protein restriction. Finally, while all major taxa for which sufficient data exist (i.e. arthropods, mammals, fish) showed condition dependence of ejaculate traits, we detected some taxonomic differences in the life stage that is most sensitive to nutrient limitation, and in the degree of condition dependence of specific ejaculate traits. Together, these biologically relevant factors accounted for nearly 20% of the total variance in ejaculate responses to nutrient limitation. Interestingly, body size showed considerably stronger condition-dependent responses compared to ejaculate traits, suggesting that ejaculate trait expression may be strongly canalised to protect important reproductive functions, or that the cost of producing an ejaculate is relatively low. Taken together, our findings show that condition-dependence of ejaculate traits is taxonomically widespread, but there are also many interesting, biologically relevant sources of variation that require further investigation. In particular, further research is needed to understand the differences in selective pressures that result in differential patterns of ejaculate condition dependence across taxa and ejaculate traits.
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Affiliation(s)
- Erin L Macartney
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, UNSW Australia, Sydney, New South Wales, Australia
| | - Angela J Crean
- Sydney School of Veterinary Science, The University of Sydney, Sydney, New South Wales, Australia
| | - Shinichi Nakagawa
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, UNSW Australia, Sydney, New South Wales, Australia
| | - Russell Bonduriansky
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, UNSW Australia, Sydney, New South Wales, Australia
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12
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Macartney EL, Nicovich PR, Bonduriansky R, Crean AJ. Developmental diet irreversibly shapes male post-copulatory traits in the neriid fly Telostylinus angusticollis. J Evol Biol 2018; 31:1894-1902. [PMID: 30267554 DOI: 10.1111/jeb.13384] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/20/2018] [Accepted: 09/23/2018] [Indexed: 01/17/2023]
Abstract
Nutrient availability has been shown to influence investment in many fitness-related traits, including male reproductive success. Many studies have demonstrated that a reduction in nutrient availability alters male post-copulatory trait expression, with some studies demonstrating an effect of developmental nutrients and others, an effect of adult nutrients. However, few studies have manipulated both developmental and adult nutrients in the same experiment. Therefore, it is not clear what life-stage has the greatest effect on post-copulatory trait expression, and if the effects of developmental and adult nutrients can interact. Here, we investigate effects of developmental and adult nutrition on male testes and accessory gland size, sperm movement within the female reproductive tract and sperm length in the neriid fly, Telostylinus angusticollis. We found that males fed a nutrient-poor developmental diet produced sperm with a reduced tail beat frequency and had smaller testes and accessory glands compared to males fed a nutrient-rich developmental diet. In contrast, we found no effects of adult nutrition on any traits measured, although sperm length was correlated with body size and male age but unaffected by nutrition at any stage. Therefore, investment in adult post-copulatory traits is determined early on by developmental nutrients in male neriid flies, and this effect is not altered by adult nutrient availability.
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Affiliation(s)
- Erin L Macartney
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, UNSW Australia, Sydney, NSW, Australia
| | - Philip R Nicovich
- ARC Centre of Excellence in Advanced Molecular Imaging and EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, NSW, Australia.,Allen Institute for Brain Science, Seattle, Washington, USA
| | - Russell Bonduriansky
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, UNSW Australia, Sydney, NSW, Australia
| | - Angela J Crean
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, UNSW Australia, Sydney, NSW, Australia.,Sydney School of Veterinary Science, The University of Sydney, Sydney, NSW, Australia
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13
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