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Somjee U, Marting P, Anzaldo S, Simmons LW, Painting CJ. Extreme range in adult body size reveals hidden trade-offs among sexually selected traits. Evolution 2024:qpae084. [PMID: 38900629 DOI: 10.1093/evolut/qpae084] [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: 11/25/2023] [Revised: 05/13/2024] [Accepted: 05/24/2024] [Indexed: 06/22/2024]
Abstract
Sexually selected weapons used to monopolize mating opportunities are predicted to trade-off with traits used in competition for fertilization. Yet, the limited size range typically found among adults of a species often precludes clear comparisons between population-level and individual-level relative trait investment. The jousting weevil, Brentus anchorago (Coleoptera: Brentidae), varies more than 26-fold in body mass, which is among the most extreme adult body size ranges of any solitary terrestrial species. We reveal a trade-off at a population level: hypermetric scaling in male weapons (slope = 1.59) and a closely mirrored reversal in allocation to postcopulatory traits (slope = 0.54). Yet, at the individual level, we find the opposite pattern; males that invest relatively more in weapons for their size class also invest more in postcopulatory traits. Across 36 dung beetle and 41 brentine weevil species, we find the allometric slope explains more trait variation at larger body size ranges; in brentines, population-level scaling patterns become more detectable in species with a larger range in adult body size. Our findings reveal that population-level allometries and individual-level trade-offs can both be important in shaping relative trait allocation; we highlight that the adult body size range is rarely examined but may be integral to gaining a deeper understanding of trade-offs in reproductive allocation.
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Affiliation(s)
- Ummat Somjee
- Department of Integrative Biology, University of Texas, Austin, TX, United States
- Smithsonian Tropical Research Institute, Balboa, Panama
| | - Peter Marting
- Department of Biological Sciences, Auburn University, Auburn, AL, United States
| | - Salvatore Anzaldo
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Leigh W Simmons
- School of Biological Sciences, University of Western Australia, Perth, WA, Australia
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2
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Chung MHJ, Fox RJ, Jennions MD. Male allocation to ejaculation and mating effort imposes different life history trade-offs. PLoS Biol 2024; 22:e3002519. [PMID: 38787858 PMCID: PMC11156437 DOI: 10.1371/journal.pbio.3002519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 06/06/2024] [Accepted: 05/13/2024] [Indexed: 05/26/2024] Open
Abstract
When males compete, sexual selection favors reproductive traits that increase their mating or fertilization success (pre- and postcopulatory sexual selection). It is assumed that males face a trade-off between these 2 types of sexual traits because they both draw from the same pool of resources. Consequently, allocation into mate acquisition or ejaculation should create similar trade-offs with other key life history traits. Tests of these assumptions are exceedingly rare. Males only ejaculate after they mate, and the costs of ejaculation are therefore highly confounded with those of mating effort. Consequently, little is known about how each component of reproductive allocation affects a male's future performance. Here, we ran an experiment using a novel technique to distinguish the life history costs of mating effort and ejaculation for mosquitofish (Gambusia holbrooki). We compared manipulated males (mate without ejaculation), control males (mate and ejaculate), and naïve males (neither mate nor ejaculate) continuously housed with a female and 2 rival males. We assessed their growth, somatic maintenance, mating and fighting behavior, and sperm traits after 8 and 16 weeks. Past mating effort significantly lowered a male's future mating effort and growth, but not his sperm production, while past sperm release significantly lowered a male's future ejaculate quantity, but not his mating effort. Immune response was the only trait impacted by both past mating effort and past ejaculation. These findings challenge the assumption that male reproductive allocation draws from a common pool of resources to generate similar life history costs later in life. Instead, we provide clear evidence that allocation into traits under pre- and postcopulatory sexual selection have different trait-specific effects on subsequent male reproductive performance.
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Affiliation(s)
- Meng-Han Joseph Chung
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australia
| | - Rebecca J. Fox
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australia
| | - Michael D. Jennions
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University, Stellenbosch, South Africa
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3
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Miller CW, Kimball RT, Forthman M. The evolution of multi-component weapons in the superfamily of leaf-footed bugs. Evolution 2024; 78:635-651. [PMID: 38253050 DOI: 10.1093/evolut/qpae011] [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: 04/24/2023] [Revised: 11/28/2023] [Accepted: 01/19/2024] [Indexed: 01/24/2024]
Abstract
Sexually selected weapons, such as the antlers of deer, claws of crabs, and tusks of beaked whales, are strikingly diverse across taxa and even within groups of closely related species. Phylogenetic comparative studies have typically taken a simplified approach to investigate the evolution of weapon diversity, examining the gains and losses of entire weapons, major shifts in size or type, or changes in location. Less understood is how individual weapon components evolve and assemble into a complete weapon. We addressed this question by examining weapon evolution in the diverse, multi-component hind-leg and body weapons of leaf-footed bugs, superfamily Coreoidea (Hemiptera: Heteroptera). Male leaf-footed bugs use their morphological weapons to fight for access to mating territories. We used a large multilocus dataset comprised of ultraconserved element loci for 248 species and inferred evolutionary transitions among component states using ancestral state estimation. Our results suggest that weapons added components over time with some evidence of a cyclical evolutionary pattern-gains of components followed by losses and then gains again. Furthermore, our best estimate indicated that certain trait combinations evolved repeatedly across the phylogeny, suggesting that they function together in battle or that they are genetically correlated. This work reveals the remarkable and dynamic evolution of weapon form in the leaf-footed bugs and provides insights into weapon assembly and disassembly over evolutionary time.
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Affiliation(s)
- Christine W Miller
- Entomology & Nematology Department, University of Florida, Gainesville, FL, United States
| | - Rebecca T Kimball
- Department of Biology, University of Florida, Gainesville, FL, United States
| | - Michael Forthman
- Entomology & Nematology Department, University of Florida, Gainesville, FL, United States
- California State Collection of Arthropods, Plant Pest Diagnostics Branch, California Department of Food & Agriculture, Sacramento, CA, United States
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4
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Valencia-Aguilar A, Ringler E, Lüpold S, Guayasamin JM, Prado CPA. Evolutionary trade-offs between testes size and parenting in Neotropical glassfrogs. Proc Biol Sci 2024; 291:20240054. [PMID: 38351799 PMCID: PMC10865008 DOI: 10.1098/rspb.2024.0054] [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: 01/08/2024] [Accepted: 01/18/2024] [Indexed: 02/16/2024] Open
Abstract
In males, large testes size signifies high sperm production and is commonly linked to heightened sperm competition levels. It may also evolve as a response to an elevated risk of sperm depletion due to multiple mating or large clutch sizes. Conversely, weapons, mate or clutch guarding may allow individuals to monopolize mating events and preclude sperm competition, thereby reducing the selection of large testes. Herein, we examined how paternal care, sexual size dimorphism (SSD), weaponry and female fecundity are linked to testes size in glassfrogs. We found that paternal care was associated with a reduction in relative testes size, suggesting an evolutionary trade-off between testes size and parenting. Although females were slightly larger than males and species with paternal care tended to have larger clutches, there was no significant relationship between SSD, clutch size and relative testes size. These findings suggest that the evolution of testes size in glassfrogs is influenced by sperm competition risk, rather than sperm depletion risk. We infer that clutch guarding precludes the risk of fertilization by other males and consequently diminishes selective pressure for larger testes. Our study highlights the prominent role of paternal care in the evolution of testes size in species with external fertilization.
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Affiliation(s)
- Anyelet Valencia-Aguilar
- Pós-Graduação em Ecologia, Evolução e Biodiversidade, Instituto de Biociências, São Paulo State University (Unesp), Rio Claro, São Paulo 13506-900, Brazil
- Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, 3032 Bern, Switzerland
| | - Eva Ringler
- Division of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, 3032 Bern, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
| | - Juan M. Guayasamin
- Instituto Biósfera USFQ, Laboratorio de Biología Evolutiva, Universidad San Francisco de Quito USFQ Cumbayá, Quito, Ecuador
| | - Cynthia P. A. Prado
- Pós-Graduação em Ecologia, Evolução e Biodiversidade, Instituto de Biociências, São Paulo State University (Unesp), Rio Claro, São Paulo 13506-900, Brazil
- Departamento de Morfologia e Fisiologia Animal, FCAV, São Paulo State University (Unesp), Jaboticabal, São Paulo 14884-900, Brazil
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5
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Liao W, Jiang Y, Jin L, Lüpold S. How hibernation in frogs drives brain and reproductive evolution in opposite directions. eLife 2023; 12:RP88236. [PMID: 38085091 PMCID: PMC10715729 DOI: 10.7554/elife.88236] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023] Open
Abstract
Environmental seasonality can promote the evolution of larger brains through cognitive and behavioral flexibility but can also hamper it when temporary food shortage is buffered by stored energy. Multiple hypotheses linking brain evolution with resource acquisition and allocation have been proposed for warm-blooded organisms, but it remains unclear how these extend to cold-blooded taxa whose metabolism is tightly linked to ambient temperature. Here, we integrated these hypotheses across frogs and toads in the context of varying brumation (hibernation) durations and their environmental correlates. We showed that protracted brumation covaried negatively with brain size but positively with reproductive investment, likely in response to brumation-dependent changes in the socio-ecological context and associated selection on different tissues. Our results provide novel insights into resource allocation strategies and possible constraints in trait diversification, which may have important implications for the adaptability of species under sustained environmental change.
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Affiliation(s)
- Wenbo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal UniversitySichuanChina
- Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City, China West Normal UniversityNanchongChina
- Institute of Eco-Adaptation in Amphibians and Reptiles, China West Normal UniversityNanchongChina
| | - Ying Jiang
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal UniversitySichuanChina
- Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City, China West Normal UniversityNanchongChina
- Institute of Eco-Adaptation in Amphibians and Reptiles, China West Normal UniversityNanchongChina
| | - Long Jin
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal UniversitySichuanChina
- Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City, China West Normal UniversityNanchongChina
- Institute of Eco-Adaptation in Amphibians and Reptiles, China West Normal UniversityNanchongChina
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of ZurichZurichSwitzerland
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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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7
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Tuschhoff E, Wiens JJ. Evolution of sexually selected traits across animals. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1042747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Sexual selection is thought to be a major driver of phenotypic diversity and diversification in animals, but large-scale evolutionary patterns in sexually selected (SS) traits remain largely unknown. Here, we survey and analyze the evolution of these traits across animal phylogeny. We find that female mate choice appears to be the most widespread mechanism of sexual selection, but male-male competition appears to be almost as frequent in chordates and male mate choice is also common in arthropods. Among sensory types, tactile traits appear to be most widespread whereas auditory traits are relatively uncommon. Rather than being ubiquitous or randomly distributed across animals, most of these different types of SS traits are confined to clades in arthropods and chordates, which form “hotspots” for the evolution of these diverse trait types. Thus, different sensory types show accelerated rates of evolution in these clades. Moreover, different types of SS traits are strongly correlated with each other in their evolution across animals. Finally, despite the intensive interest in the role of sexual selection in speciation, we find only limited support for the idea that SS traits drive large-scale patterns of diversification and species richness across all animals.
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8
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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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9
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Effects of Larval Diet on the Male Reproductive Traits in the West Indian Sweet Potato Weevils Euscepes postfasciatus (Coleoptera: Curculionidae). INSECTS 2022; 13:insects13040389. [PMID: 35447831 PMCID: PMC9031274 DOI: 10.3390/insects13040389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/31/2022] [Accepted: 04/13/2022] [Indexed: 01/27/2023]
Abstract
Simple Summary In insects, it is known that the diet during the larval stage affects traits in the adult stage. However, it is still unclear how it affects reproductive traits such as ejaculation. The ejaculate contains many proteins and therefore requires much nutrition, so the larval diet strongly influences it. Males of the West Indian sweet potato weevil Euscepes postfasciatus use accessory gland substances to inhibit remating by females. Crossing experiments were conducted using lines reared on artificial diets or sweet potato tubers during the larval stage, and the refractory period was examined. The results showed that the larval stage diet had a significant effect on the refractory period of females. We also found one protein of approximately 15 kDa in size expressed only in the treatments reared on sweet potatoes. To our knowledge, this is the first study to show that larval diet qualitatively influences male ejaculate and female refractory period. Abstract Larval diet significantly affects adult traits, although less is known about how they affect reproductive traits. Males of West Indian sweet potato weevil Euscepes postfasciatus deliver a remating inhibitor along with sperm to their mates during mating, leading to a refractory period (the period before females mate again). Crossing experiments were conducted using lines reared on artificial diets, including sweet potato powder (AD) or sweet potato tubers (SP) during the larval stage, and the refractory period was examined. We also examined whether the larval diet qualitatively or quantitatively altered male ejaculate. The results showed that the refractory period was significantly longer in the SP treatment than in the AD treatment for males and females. There was no significant difference in ejaculate volume. However, the number of sperm in the testes-seminal vesicles complex was significantly higher in the SP treatment. Additionally, SDS-PAGE revealed that the ejaculate was qualitatively different depending on the larval diet, and one protein of approximately 15 kDa in size was expressed only in the SP treatments. Revealing how larval diet affects reproductive traits in adult males will help shed light on the diverse evolution of insect mating systems and reproductive behavior.
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10
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Dougherty LR, Skirrow MJA, Jennions MD, Simmons LW. Male alternative reproductive tactics and sperm competition: a meta-analysis. Biol Rev Camb Philos Soc 2022; 97:1365-1388. [PMID: 35229450 PMCID: PMC9541908 DOI: 10.1111/brv.12846] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 01/16/2023]
Abstract
In many animal species, males may exhibit one of several discrete, alternative ways of obtaining fertilisations, known as alternative reproductive tactics (ARTs). Males exhibiting ARTs typically differ in the extent to which they invest in traits that improve their mating success, or the extent to which they face sperm competition. This has led to the widespread prediction that males exhibiting ARTs associated with a high sperm competition risk, or lower investment into traits that improve their competitiveness before mating, should invest more heavily into traits that improve their competitiveness after mating, such as large ejaculates and high-quality sperm. However, despite many studies investigating this question since the 1990s, evidence for differences in sperm and ejaculate investment between male ARTs is mixed, and there has been no quantitative summary of this field. Following a systematic review of the literature, we performed a meta-analysis examining how testes size, sperm number and sperm traits differ between males exhibiting ARTs that face either a high or low sperm competition risk, or high or low investment in traits that increase mating success. We obtained data from 92 studies and 67 species from across the animal kingdom. Our analyses showed that male fish exhibiting ARTs facing a high sperm competition risk had significantly larger testes (after controlling for body size) than those exhibiting tactics facing a low sperm competition risk. However, this effect appears to be due to the inappropriate use of the gonadosomatic index as a body-size corrected measure of testes investment, which overestimates the difference in testes investment between male tactics in most cases. We found no significant difference in sperm number between males exhibiting different ARTs, regardless of whether sperm were measured from the male sperm stores or following ejaculation. We also found no significant difference in sperm traits between males exhibiting different ARTs, with the exception of sperm adenosine triphosphate (ATP) content in fish. Finally, the difference in post-mating investment between male ARTs was not influenced by the extent to which tactics were flexible, or by the frequency of sneakers in the population. Overall, our results suggest that, despite clear theoretical predictions, there is little evidence that male ARTs differ substantially in investment into sperm and ejaculates across species. The incongruence between theoretical and empirical results could be explained if (i) theoretical models fail to account for differences in overall resource levels between males exhibiting different ARTs or fundamental trade-offs between investment into different ejaculate and sperm traits, and (ii) studies often use sperm or ejaculate traits that do not reflect overall post-mating investment accurately or affect fertilisation success.
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Affiliation(s)
- Liam R Dougherty
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Crown Street, Liverpool, L69 7RB, U.K
| | - Michael J A Skirrow
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Michael D Jennions
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
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11
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Harrison LM, Noble DWA, Jennions MD. A meta-analysis of sex differences in animal personality: no evidence for the greater male variability hypothesis. Biol Rev Camb Philos Soc 2021; 97:679-707. [PMID: 34908228 DOI: 10.1111/brv.12818] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 11/13/2021] [Accepted: 11/17/2021] [Indexed: 12/18/2022]
Abstract
The notion that men are more variable than women has become embedded into scientific thinking. For mental traits like personality, greater male variability has been partly attributed to biology, underpinned by claims that there is generally greater variation among males than females in non-human animals due to stronger sexual selection on males. However, evidence for greater male variability is limited to morphological traits, and there is little information regarding sex differences in personality-like behaviours for non-human animals. Here, we meta-analysed sex differences in means and variances for over 2100 effects (204 studies) from 220 species (covering five broad taxonomic groups) across five personality traits: boldness, aggression, activity, sociality and exploration. We also tested if sexual size dimorphism, a proxy for sex-specific sexual selection, explains variation in the magnitude of sex differences in personality. We found no significant differences in personality between the sexes. In addition, sexual size dimorphism did not explain variation in the magnitude of the observed sex differences in the mean or variance in personality for any taxonomic group. In sum, we find no evidence for widespread sex differences in variability in non-human animal personality.
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Affiliation(s)
- Lauren M Harrison
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Daniel W A Noble
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Michael D Jennions
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
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12
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Tan H, Bertram MG, Martin JM, Ecker TE, Hannington SL, Saaristo M, O'Bryan MK, Wong BBM. The endocrine disruptor 17β-trenbolone alters the relationship between pre- and post-copulatory sexual traits in male mosquitofish (Gambusia holbrooki). THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 790:148028. [PMID: 34087738 DOI: 10.1016/j.scitotenv.2021.148028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/21/2021] [Accepted: 05/22/2021] [Indexed: 06/12/2023]
Abstract
It is now well-established that reproduction in wildlife can be disrupted by anthropogenic environmental changes, such as chemical pollution. However, very little is known about how these pollutants might affect the interplay between pre- and post-copulatory mechanisms of sexual selection. Here, we investigated the impacts of 21-day exposure of male eastern mosquitofish (Gambusia holbrooki) to a field-realistic level (average measured concentration: 11 ng/L) of the endocrine-disrupting chemical 17β-trenbolone (17β-TB) on pre- and post-copulatory reproductive traits. We examined male reproductive behaviour by testing the time spent near a female behind a partition, as well as the number of copulation attempts made, and the time spent chasing a female in a free-swimming context. Sperm traits were also assayed for all males. We found that exposure of male fish to 17β-TB altered the relationship between key pre- and post-copulatory reproductive traits. Furthermore, 17β-TB-exposed males had, on average, a higher percentage of motile sperm, and performed fewer copulation attempts than unexposed males. However, there was no overall effect of 17β-TB exposure on either the time males spent associating with or chasing females. Taken together, our findings demonstrate the potential for chemical pollutants to affect both pre- and post-copulatory sexual traits, and the interplay between these mechanisms of sexual selection in contaminated wildlife.
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Affiliation(s)
- Hung Tan
- School of Biological Sciences, Monash University, Victoria, Australia
| | - Michael G Bertram
- School of Biological Sciences, Monash University, Victoria, Australia; Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden.
| | - Jake M Martin
- School of Biological Sciences, Monash University, Victoria, Australia
| | - Tiarne E Ecker
- School of Biological Sciences, Monash University, Victoria, Australia
| | | | - Minna Saaristo
- School of Biological Sciences, Monash University, Victoria, Australia; Department of Biosciences, Åbo Akademi University, Turku, Finland; EPA Victoria, Water Sciences, Victoria, Australia
| | - Moira K O'Bryan
- School of Biological Sciences, Monash University, Victoria, Australia
| | - Bob B M Wong
- School of Biological Sciences, Monash University, Victoria, Australia
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13
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Tyler F, Haverkos S, Imm A, Polak M. Analysis of correlated responses in key ejaculatory traits to artificial selection on a diversifying secondary sexual trait. JOURNAL OF INSECT PHYSIOLOGY 2021; 133:104291. [PMID: 34364848 DOI: 10.1016/j.jinsphys.2021.104291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 07/27/2021] [Accepted: 08/03/2021] [Indexed: 06/13/2023]
Abstract
Positive genetic covariance between male sexual display traits and fertilizing capacity can arise through different mechanisms and has important implications for sexual trait evolution. Evidence for such genetic covariance is rare, and when it has been found, specific physiological traits underlying variation in fertilization success linked to trait expression have not been identified. A previous study of correlated responses to bidirectional artificial selection on the male sex comb, a secondary sexual trait, in Drosophila bipectinata Duda documented a positive genetic correlation between sexual trait size and competitive fertilization success, and found that transcript levels of multiple seminal fluid proteins (SFPs) were significantly increased in the large sex comb (high) genetic lines. These results suggest that changes in SFP activity may be a causal factor underlying the increased fertilizing capacity of high line males. Here, we tested for correlated responses to this selection in a suite of additional reproductive traits, measured in the context of variation in male age and exposure to rivals. Whereas several traits including sperm length, number and viability, and accessory gland size, increased with age, only sperm viability was influenced by selection treatment, but in complex fashion. Sperm viability of high line males surpassed that of their smaller-combed counterparts when they had been housed with rivals and were 5-6 days old or older. Interestingly, this interaction effect was evident for sperm sampled from the female seminal receptacle, but not from the male seminal vesicles (where sperm have yet to be combined with accessory gland products), consistent with the differential SFP activity between the lines previously found. Our results suggest that differences in sperm quality (as viability) may be a contributing factor to the positive genetic correlation between sexual trait size and competitive fertilization capacity in D. bipectinata.
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Affiliation(s)
- Frances Tyler
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, USA
| | - Sarah Haverkos
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, USA
| | - Alexandria Imm
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, USA
| | - Michal Polak
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, USA.
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14
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Cavender KR, Ricker TA, Lyon MO, Shelby EA, Miller CW, Moore PJ. The trade-off between investment in weapons and fertility is mediated through spermatogenesis in the leaf-footed cactus bug Narnia femorata. Ecol Evol 2021; 11:8776-8782. [PMID: 34257927 PMCID: PMC8258196 DOI: 10.1002/ece3.7686] [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: 12/23/2020] [Revised: 03/06/2021] [Accepted: 03/16/2021] [Indexed: 11/08/2022] Open
Abstract
Males have the ability to compete for fertilizations through both precopulatory and postcopulatory intrasexual competition. Precopulatory competition has selected for large weapons and other adaptations to maximize access to females and mating opportunities, while postcopulatory competition has resulted in ejaculate adaptations to maximize fertilization success. Negative associations between these strategies support the hypothesis that there is a trade-off between success at pre- and postcopulatory mating success. Recently, this trade-off has been demonstrated with experimental manipulation. Males of the leaf-footed cactus bug Narnia femorata use hind limbs as the primary weapon in male-male competition. However, males can drop a hind limb to avoid entrapment. When this autotomy occurs during development, they invest instead in large testes. While evolutionary outcomes of the trade-offs between pre- and postcopulatory strategies have been identified, less work has been done to identify proximate mechanisms by which the trade-off might occur, perhaps because the systems in which the trade-offs have been investigated are not ones that have the molecular tools required for exploring mechanism. Here, we applied knowledge from a related model species for which we have developmental knowledge and molecular tools, the milkweed bug Oncopeltus fasciatus, to investigate the proximate mechanism by which autotomized N. femorata males developed larger testes. Autotomized males had evidence of a higher rate of transit amplification divisions in the spermatogonia, which would result more spermatocytes and thus in greater sperm numbers. Identification of mechanisms underlying a trade-off can help our understanding of the direction and constraints on evolutionary trajectories and thus the evolutionary potential under multiple forms of selection.
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Affiliation(s)
| | - Tessa A. Ricker
- Entomology and Nematology DepartmentUniversity of FloridaGainesvilleFLUSA
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15
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Brusa JL, Rotella JJ, Banner KM, Hutchins PR. Challenges and opportunities for comparative studies of survival rates: An example with male pinnipeds. Ecol Evol 2021; 11:7980-7999. [PMID: 34188866 PMCID: PMC8216918 DOI: 10.1002/ece3.7627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 03/11/2021] [Accepted: 04/13/2021] [Indexed: 11/30/2022] Open
Abstract
Survival rates are a central component of life-history strategies of large vertebrate species. However, comparative studies seldom investigate interspecific variation in survival rates with respect to other life-history traits, especially for males. The lack of such studies could be due to the challenges associated with obtaining reliable datasets, incorporating information on the 0-1 probability scale, or dealing with several types of measurement error in life-history traits, which can be a computationally intensive process that is often absent in comparative studies. We present a quantitative approach using a Bayesian phylogenetically controlled regression with the flexibility to incorporate uncertainty in estimated survival rates and quantitative life-history traits while considering genetic similarity among species and uncertainty in relatedness. As with any comparative analysis, our approach makes several assumptions regarding the generalizability and comparability of empirical data from separate studies. Our model is versatile in that it can be applied to any species group of interest and include any life-history traits as covariates. We used an unbiased simulation framework to provide "proof of concept" for our model and applied a slightly richer model to a real data example for pinnipeds. Pinnipeds are an excellent taxonomic group for comparative analysis, but survival rate data are scarce. Our work elucidates the challenges associated with addressing important questions related to broader ecological life-history patterns and how survival-reproduction trade-offs might shape evolutionary histories of extant taxa. Specifically, we underscore the importance of having high-quality estimates of age-specific survival rates and information on other life-history traits that reasonably characterize a species for accurately comparing across species.
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Affiliation(s)
- Jamie L. Brusa
- Department of EcologyMontana State UniversityBozemanMTUSA
- School of Environmental and Forest SciencesUniversity of WashingtonSeattleWAUSA
| | - Jay J. Rotella
- Department of EcologyMontana State UniversityBozemanMTUSA
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16
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Chung MHJ, Jennions MD, Fox RJ. Quantifying the costs of pre- and postcopulatory traits for males: Evidence that costs of ejaculation are minor relative to mating effort. Evol Lett 2021; 5:315-327. [PMID: 34367658 PMCID: PMC8327938 DOI: 10.1002/evl3.228] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 12/12/2022] Open
Abstract
Although it is widely stated that both mating behavior and sperm traits are energetically costly for males, we currently lack empirical estimates of the relative costs to males of pre‐ versus postcopulatory investments. Such estimates require the experimental separation of the act of mating from that of ejaculation, which is a nontrivial logistical challenge. Here, we overcome this challenge using a novel morphological manipulation (gonopodium tip ablation) in the eastern mosquitofish (Gambusia holbrooki) to tease apart investment in mating effort from that in sperm replenishment following ejaculation. We quantified the relative cumulative costs of investing in mating effort and ejaculation by comparing somatic traits and reproductive performance among three types of males: ablated males that could attempt to mate but not ejaculate; unablated males that could both mate and ejaculate; and control males that had no access to females. We show that, after eight weeks, mating investment significantly reduces both body growth and immunocompetence and results in a significant decline in mating effort. In contrast, cumulative investment into sperm replenishment following ejaculation has few detectable effects that are only apparent in smaller males. These minor costs occur despite the fact that G. holbrooki has very high levels of sperm competition and multiple mating by both sexes, which is usually associated with elevated levels of sperm production. Crucially, our study is the first, to our knowledge, to experimentally compare the relative costs of pre‐ and postcopulatory investment on components of male fitness in a vertebrate.
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Affiliation(s)
- Meng-Han Joseph Chung
- Division of Ecology and Evolution Research School of Biology Australian National University Canberra ACT 2601 Australia
| | - Michael D Jennions
- Division of Ecology and Evolution Research School of Biology Australian National University Canberra ACT 2601 Australia
| | - Rebecca J Fox
- Division of Ecology and Evolution Research School of Biology Australian National University Canberra ACT 2601 Australia
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17
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Reuland C, Simmons LW, Lüpold S, Fitzpatrick JL. Weapons Evolve Faster Than Sperm in Bovids and Cervids. Cells 2021; 10:cells10051062. [PMID: 33947050 PMCID: PMC8145498 DOI: 10.3390/cells10051062] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/25/2021] [Accepted: 04/27/2021] [Indexed: 12/13/2022] Open
Abstract
In polyandrous species, males face reproductive competition both before and after mating. Sexual selection thus shapes the evolution of both pre- and postcopulatory traits, creating competing demands on resource allocation to different reproductive episodes. Traits subject to strong selection exhibit accelerated rates of phenotypic divergence, and examining evolutionary rates may inform us about the relative importance and potential fitness consequences of investing in traits under either pre- or postcopulatory sexual selection. Here, we used a comparative approach to assess evolutionary rates of key competitive traits in two artiodactyl families, bovids (family Bovidae) and cervids (family Cervidae), where male–male competition can occur before and after mating. We quantified and compared evolutionary rates of male weaponry (horns and antlers), body size/mass, testes mass, and sperm morphometrics. We found that weapons evolve faster than sperm dimensions. In contrast, testes and body mass evolve at similar rates. These results suggest strong, but differential, selection on both pre- and postcopulatory traits in bovids and cervids. Furthermore, we documented distinct evolutionary rates among different sperm components, with sperm head and midpiece evolving faster than the flagellum. Finally, we demonstrate that, despite considerable differences in weapon development between bovids and cervids, the overall evolutionary patterns between these families were broadly consistent.
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Affiliation(s)
- Charel Reuland
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden;
| | - Leigh W. Simmons
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, Crawley, WA 6009, Australia;
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland;
| | - John L. Fitzpatrick
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden;
- Correspondence:
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18
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De Nardo AN, Roy J, Sbilordo SH, Lüpold S. Condition-dependent interaction between mating success and competitive fertilization success in Drosophila melanogaster. Evolution 2021; 75:2014-2026. [PMID: 33834478 DOI: 10.1111/evo.14228] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 02/06/2021] [Accepted: 03/13/2021] [Indexed: 12/12/2022]
Abstract
Dietary restriction during development can affect adult body size and condition. In many species, larger (high-condition) males gain higher mating success through male-male competition and female choice, and female condition can affect the extent of both female mate choice and male investment in courtship or ejaculates. However, few studies have examined the joint effects and interplay of male and female condition during both the pre- and the postcopulatory phases of sexual selection. We therefore manipulated the larval diet of male and female Drosophila melanogaster to study how body size variation in both sexes biases competitive outcomes at different reproductive stages, from mating to paternity. We did not find a difference in mate preference or mating latency between females of different conditions, nor any interaction between male and female conditions. However, large males were more successful in gaining matings, but only when in direct competition, whereas mating latencies were shorter for low-condition males in noncompetitive settings. Small males also transferred more sperm to nonvirgin females, displaced a larger proportion of resident sperm, and achieved higher paternity shares per mating than large males. In agreement with existing theory, we suggest that small males might partially compensate for their low mating success by strategically investing in larger sperm numbers and potentially other, unmeasured ejaculate traits, when they do have a mating opportunity.
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Affiliation(s)
- Alessio N De Nardo
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
| | - Jeannine Roy
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
| | - Sonja H Sbilordo
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
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19
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Reuland C, Culbert BM, Fernlund Isaksson E, Kahrl AF, Devigili A, Fitzpatrick JL. Male-male behavioral interactions drive social-dominance-mediated differences in ejaculate traits. Behav Ecol 2021; 32:168-177. [PMID: 33708008 PMCID: PMC7937186 DOI: 10.1093/beheco/araa118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 09/15/2020] [Accepted: 10/08/2020] [Indexed: 12/29/2022] Open
Abstract
Higher social status is expected to result in fitness benefits as it secures access to potential mates. In promiscuous species, male reproductive success is also determined by an individual’s ability to compete for fertilization after mating by producing high-quality ejaculates. However, the complex relationship between a male’s investment in social status and ejaculates remains unclear. Here, we examine how male social status influences ejaculate quality under a range of social contexts in the pygmy halfbeak Dermogenys collettei, a small, group-living, internally fertilizing freshwater fish. We show that male social status influences ejaculate traits, both in the presence and absence of females. Dominant males produced faster swimming and more viable sperm, two key determinants of ejaculate quality, but only under conditions with frequent male–male behavioral interactions. When male–male interactions were experimentally reduced through the addition of a refuge, differences in ejaculate traits of dominant and subordinate males disappeared. Furthermore, dominant males were in a better condition, growing faster, and possessing larger livers, highlighting a possible condition dependence of competitive traits. Contrary to expectations, female presence or absence did not affect sperm swimming speed or testes mass. Together, these results suggest a positive relationship between social status and ejaculate quality in halfbeaks and highlight that the strength of behavioral interactions between males is a key driver of social-status-dependent differences in ejaculate traits.
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Affiliation(s)
- Charel Reuland
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, Stockholm, Sweden
| | - Brett M Culbert
- Department of Integrative Biology, University of Guelph, Guelph, Canada
| | | | - Ariel F Kahrl
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, Stockholm, Sweden
| | - Alessandro Devigili
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, Stockholm, Sweden
| | - John L Fitzpatrick
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, Stockholm, Sweden
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20
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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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21
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Martinez G, Garcia C. Sexual selection and sperm diversity in primates. Mol Cell Endocrinol 2020; 518:110974. [PMID: 32926966 DOI: 10.1016/j.mce.2020.110974] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/31/2020] [Accepted: 07/31/2020] [Indexed: 12/30/2022]
Abstract
Many aspects of primate sperm physiology and reproductive behavior have been influenced by sexual selection, especially in taxa exposed to sperm competition where females mate with multiple partners. Primate sperm diversity reflects therefore the evolutionary divergences of the different primate species and the impact of a combination of variables exerting selection pressures on sperm form, function, and competition. Thereby, mating systems, life cycle or ecological variables are some of the important factors driving sperm diversity and explaining variation in terms of sperm morphology, parameters or male sexual characters. Here, we address primate sperm diversity through a compilation of all data available in the literature concerning primate sperm parameters and relationships between them. We also review the factors that can influence primate sperm diversity (e.g. mating systems, trade-off between investments in precopulatory and postcopulatory sexual traits, male and female sexual behaviors, seasonality, social constraints, testosterone levels), and discuss also their relevance to our understanding of human reproduction.
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Affiliation(s)
- Guillaume Martinez
- Hôpital Couple-Enfant, Centre Hospitalier Universitaire de Grenoble, UM de Génétique Chromosomique, F-38000, Grenoble, France; Genetic Epigenetic and Therapies of Infertility, Institute for Advanced Biosciences INSERM U1209, CNRS UMR5309, F-38000, Grenoble, France.
| | - Cécile Garcia
- UMR 7206 Eco-anthropologie, CNRS - MNHN - Université de Paris, Musée de l'Homme, 75016, Paris, France.
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22
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Parker GA. Conceptual developments in sperm competition: a very brief synopsis. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200061. [PMID: 33070727 DOI: 10.1098/rstb.2020.0061] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The past half century has seen the development of the field of post-ejaculatory sexual selection, the sequel to sexual selection for mate-acquisition (pre-ejaculatory) described by Darwin. In richness and diversity of adaptations, post-ejaculatory selection rivals that of pre-ejaculatory sexual selection. Anisogamy-and hence two sexes-likely arose by primeval gamete competition, and sperm competition remains a major force maintaining high sperm numbers. The post-ejaculatory equivalent of male-male competition for matings, sperm competition was an intense ancestral form of sexual selection, typically weakening as mobility and internal fertilization developed in many taxa, when some expenditure became diverted into pre-ejaculatory competition. Sperm competition theory has been relatively successful in explaining variation in relative testes size and sperm numbers per ejaculate and is becoming more successful in explaining variation in sperm phenotype. Sperm competition has generated many other male adaptations such as seminal fluid proteins that variously modify female reproduction towards male interests, and copulatory plugs, prolonged copulations and post-ejaculatory guarding behaviour that reduce female remating probability, many of which result in sexual conflict. This short survey of conceptual developments is intended as a broad overview, mainly as a primer for new researchers. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Geoff A Parker
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Biosciences Building, Crown Street, Liverpool L69 7ZB, UK
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23
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Spagopoulou F, Vega-Trejo R, Head ML, Jennions MD. Shifts in Reproductive Investment in Response to Competitors Lower Male Reproductive Success. Am Nat 2020; 196:355-368. [PMID: 32813996 DOI: 10.1086/709821] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractIn many species, males exhibit phenotypic plasticity in sexually selected traits when exposed to social cues about the intensity of sexual competition. To date, however, few studies have tested how this plasticity affects male reproductive success. We initially tested whether male mosquitofish, Gambusia holbrooki (Poeciliidae), change their investment in traits under pre- and postcopulatory sexual selection depending on the social environment. For a full spermatogenesis cycle, focal males were exposed to visual and chemical cues of rivals that were either present (competitive treatment) or absent (control). Males from the competitive treatment had significantly slower-swimming sperm but did not differ in sperm count from control males. When two males competed for a female, competitive treatment males also made significantly fewer copulation attempts and courtship displays than control males. Further, paternity analysis of 708 offspring from 148 potential sires, testing whether these changes in reproductive traits affected male reproductive success, showed that males previously exposed to cues about the presence of rivals sired significantly fewer offspring when competing with a control male. We discuss several possible explanations for these unusual findings.
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24
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Sperm Morphology and Male Age in Black-Throated Blue Warblers, an Ecological Model System. Animals (Basel) 2020; 10:ani10071175. [PMID: 32664407 PMCID: PMC7401543 DOI: 10.3390/ani10071175] [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: 06/16/2020] [Revised: 07/03/2020] [Accepted: 07/06/2020] [Indexed: 12/15/2022] Open
Abstract
Extra-pair paternity may drive selection on spermatozoa and ejaculate characteristics through sperm competition and cryptic female choice. Here, we examine sperm morphology in the black-throated blue warbler (Setophaga caerulescens), an ecological model species where extra-pair paternity is frequent and is linked with male age. We test whether sperm morphology relates to several aspects of male phenotype known or suspected to affect extra-pair paternity success. Sperm morphology did not correlate with the size of the white wing spot, a social status signal, nor with the volume of the cloacal protuberance. However, older males tended to have longer sperm cells. Although the sample size was limited, this pattern is intriguing, as longer cells may be advantageous in post-copulatory sexual selection and older males have larger testes and higher extra-pair paternity success in this species. Changes in sperm morphology with age are not observed in other birds, though they have been observed in insects and fishes. More research on sperm morphology is needed to clarify its role in extra-pair fertilizations in this well-studied species.
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25
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Mai 麦春兰 CL, Liao 廖文波 WB, Lüpold S, Kotrschal A. Relative Brain Size Is Predicted by the Intensity of Intrasexual Competition in Frogs. Am Nat 2020; 196:169-179. [PMID: 32673088 DOI: 10.1086/709465] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Competition over mates is a powerful force shaping trait evolution. For instance, better cognitive abilities may be beneficial in male-male competition and thus be selected for by intrasexual selection. Alternatively, investment in physical attributes favoring male performance in competition for mates may lower the resources available for brain development, and more intense male mate competition would coincide with smaller brains. To date, only indirect evidence for such relationships exists, and most studies are heavily biased toward primates and other homoeothermic vertebrates. We tested the association between male brain size (relative to body size) and male-male competition across N=30 species of Chinese anurans. Three indicators of the intensity of male mate competition-operational sex ratio (OSR), spawning-site density, and male forelimb muscle mass-were positively associated with relative brain size, whereas the absolute spawning group size was not. The relationship with the OSR and male forelimb muscle mass was stronger for the male than for the female brains. Taken together, our findings suggest that the increased cognitive abilities of larger brains are beneficial in male-male competition. This study adds taxonomic breadth to the mounting evidence for a prominent role of sexual selection in vertebrate brain evolution.
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26
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Glaudas X, Rice SE, Clark RW, Alexander GJ. The intensity of sexual selection, body size and reproductive success in a mating system with male–male combat: is bigger better? OIKOS 2020. [DOI: 10.1111/oik.07223] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xavier Glaudas
- School of Animal, Plant and Environmental Sciences, Univ. of the Witwatersrand Johannesburg PO Wits 2050 South Africa
| | - Stephen E. Rice
- Dept of Biology, San Diego State Univ. San Diego CA USA
- Dept of Natural Sciences, Fairmont State Univ. Fairmont WV USA
| | | | - Graham J. Alexander
- School of Animal, Plant and Environmental Sciences, Univ. of the Witwatersrand Johannesburg PO Wits 2050 South Africa
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27
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Gasparini C, Devigili A, Pilastro A. Sexual selection and ageing: interplay between pre- and post-copulatory traits senescence in the guppy. Proc Biol Sci 2020; 286:20182873. [PMID: 30963845 DOI: 10.1098/rspb.2018.2873] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Traits associated with mating and fertilization success are expected to senesce with age, but limited information is available on their relative rates of senescence. In polyandrous species, male reproductive fitness depends on both mating and fertilization success. Because successful mating is a prerequisite for post-copulatory sexual selection, ejaculate traits are expected to senesce faster than pre-copulatory traits, as pre-copulatory sexual selection is often deemed to be stronger than post-copulatory sexual selection. This pattern has generally been found in the few empirical studies conducted so far. We tested this prediction in the guppy ( Poecilia reticulata), a livebearing fish characterized by intense sperm competition, by comparing the expression of male sexual traits at two ages (four and nine months). Contrary to prediction, we found that post-copulatory traits senesced at a significantly slower rate than pre-copulatory traits. We also looked at whether early investment in those sexual traits affects longevity, and the interaction between sperm age (duration of sperm storage inside the male) and male age. Our results suggest that the relative senescence rate of pre- and post-copulatory sexual traits may vary among species with different mating systems and ecology.
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Affiliation(s)
- Clelia Gasparini
- 1 Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia , Crawley, Western Australia 6009 , Australia.,2 Department of Biology, University of Padova , 35131 Padova , Italy
| | - Alessandro Devigili
- 2 Department of Biology, University of Padova , 35131 Padova , Italy.,3 Department of Zoology, Stockholm University , Stockholm 106 91 , Sweden
| | - Andrea Pilastro
- 2 Department of Biology, University of Padova , 35131 Padova , Italy
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Durrant KL, Reader T, Symonds MRE. Pre- and post-copulatory traits working in concert: sexual dichromatism in passerines is associated with sperm morphology. Biol Lett 2020; 16:20190568. [PMID: 31937213 DOI: 10.1098/rsbl.2019.0568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Passerine birds produce costly traits under intense sexual selection, including elaborate sexually dichromatic plumage and sperm morphologies, to compete for fertilizations. Plumage and sperm traits vary markedly among species, but it is unknown if this reflects a trade-off between pre- and post-copulatory investment under strong sexual selection producing negative trait covariance, or variation in the strength of sexual selection among species producing positive covariance. Using phylogenetic regression, we analysed datasets describing plumage and sperm morphological traits for 278 passerine species. We found a significant positive relationship between sperm midpiece length and male plumage elaboration and sexual dichromatism. We did not find a relationship between plumage elaboration and testes mass. Our results do not support a trade-off between plumage and sperm traits, but may be indicative of variance among species in the strength of sexual selection to produce both brightly coloured plumage and costly sperm traits.
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Affiliation(s)
- Kate L Durrant
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Tom Reader
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Matthew R E Symonds
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria 3125, Australia
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29
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Kimock CM, Dubuc C, Brent LJN, Higham JP. Male morphological traits are heritable but do not predict reproductive success in a sexually-dimorphic primate. Sci Rep 2019; 9:19794. [PMID: 31874959 PMCID: PMC6930303 DOI: 10.1038/s41598-019-52633-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/18/2019] [Indexed: 11/25/2022] Open
Abstract
Sexual selection favours traits that increase reproductive success via increased competitive ability, attractiveness, or both. Male rhesus macaque (Macaca mulatta) morphological traits are likely to reflect the effects of multiple sexual selection pressures. Here, we use a quantitative genetic approach to investigate the production and maintenance of variation in male rhesus macaque morphometric traits which may be subject to sexual selection. We collected measurements of body size, canine length, and fat, from 125 male and 21 female free-ranging rhesus macaques on Cayo Santiago. We also collected testis volumes from males. We used a genetic pedigree to calculate trait heritability, to investigate potential trait trade-offs, and to estimate selection gradients. We found that variation in most male morphometric traits was heritable, but found no evidence of trait trade-offs nor that traits predicted reproductive success. Our results suggest that male rhesus macaque morphometric traits are either not under selection, or are under mechanisms of sexual selection that we could not test (e.g. balancing selection). In species subject to complex interacting mechanisms of selection, measures of body size, weaponry, and testis volume may not increase reproductive success via easily-testable mechanisms such as linear directional selection.
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Affiliation(s)
- Clare M Kimock
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY, USA.
| | - Constance Dubuc
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY, USA
| | - Lauren J N Brent
- Center for Research in Animal Behaviour, University of Exeter, Exeter, UK
| | - James P Higham
- Center for the Study of Human Origins, Department of Anthropology, New York University, New York, NY, USA
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30
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Liao WB, Zhong MJ, Lüpold S. Sperm quality and quantity evolve through different selective processes in the Phasianidae. Sci Rep 2019; 9:19278. [PMID: 31848414 PMCID: PMC6917726 DOI: 10.1038/s41598-019-55822-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 12/03/2019] [Indexed: 11/09/2022] Open
Abstract
Sperm competition is often considered the primary selective force underlying the rapid and diversifying evolution of ejaculate traits. Yet, several recent studies have drawn attention to other forms of selection with the potential of exceeding the effects of sperm competition. Since ejaculates are complex, multivariate traits, it seems plausible that different ejaculate components vary in their responses to different selective pressures. Such information, however, is generally lacking as individual ejaculate traits tend to be studied in isolation. Here, we studied the macroevolutionary patterns of ejaculate volume, sperm number, sperm length and the proportion of viable normal sperm in response to varying levels of sperm competition, body size and the duration of female sperm storage in pheasants and allies (Phasianidae). Ejaculate volume, sperm number and sperm viability were all relatively higher in polygamous than in monogamous mating systems. However, whereas ejaculate volume additionally covaried with body size, sperm number instead increased with the female sperm-storage duration, in conjunction with a decrease in sperm length. Overall, our results revealed important details on how different forms of selection can jointly shape ejaculates as complex, composite traits.
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Affiliation(s)
- Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, Sichuan, China. .,Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City, China West Normal University, Nanchong, Sichuan, 637009, China. .,Institute of Eco-adaptation in Amphibians and Reptiles, China West Normal University, Nanchong, 637009, Sichuan, China.
| | - Mao Jun Zhong
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, Sichuan, China.,Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City, China West Normal University, Nanchong, Sichuan, 637009, China.,Institute of Eco-adaptation in Amphibians and Reptiles, China West Normal University, Nanchong, 637009, Sichuan, China
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, 8057, Zurich, Switzerland
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31
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Testicular characterization and spermatogenesis of the hematophagous bat Diphylla ecaudata. PLoS One 2019; 14:e0226558. [PMID: 31835274 PMCID: PMC6910855 DOI: 10.1371/journal.pone.0226558] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 11/28/2019] [Indexed: 11/19/2022] Open
Abstract
Diphylla ecaudata is a hematophagous bat endemic of South America, with food preference for bird blood. Given the lack of information about the reproductive activity of this species, this study aimed to describe the testicular morphology and histomorphometry of D. ecaudata in order to understand its reproductive biology, specially spermatogenesis. The animals were collected in Lajes city, Rio Grande do Norte, Brazil. Following euthanasia, the testes were histologically processed for morphological, morphometric, ultrastructural and immunohistochemical analyses. Their average body weight was 24.64g, with a gonadosomatic index of 0.49%, tubulesomatic index of 0.47%, and a total of 32.20m of seminiferous tubules per gram of testis. The pre-meiotic, meiotic, and post-meiotic phases accounted for 56.20%, 9.30%, and 34.50% of the seminiferous epithelium cycle, respectively. The ultrastructure of spermiogenesis was similar to that described in other mammals and the perforatorium was not observed in the sperm. Androgen receptors were detected in Sertoli cell nuclei and Leydig cell cytoplasm, while aromatase enzyme was detected only in Sertoli cell nuclei. FGF2 and BCL-2 activities were detected in the cytoplasm of zygotene and pachytene primary spermatocytes, as well as round and elongated spermatids. D. ecaudata showed testicular pattern similar to other mammals and characteristics common to other bat species. This species stood out for its high efficiency of Sertoli cells, which presented high capacity to support germ cells, besides the highest sperm production rates among those already recorded. This study is the first step towards the knowledge of D. ecaudata reproduction and the first description of its spermatogenesis.
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32
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Chung MHJ, Jennions MD, Fox RJ. Novel ablation technique shows no sperm priming response by male eastern mosquitofish to cues of female availability. Behav Ecol Sociobiol 2019. [DOI: 10.1007/s00265-019-2779-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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33
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Baker J, Humphries S, Ferguson-Gow H, Meade A, Venditti C. Rapid decreases in relative testes mass among monogamous birds but not in other vertebrates. Ecol Lett 2019; 23:283-292. [PMID: 31755210 PMCID: PMC6973093 DOI: 10.1111/ele.13431] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/26/2019] [Accepted: 10/16/2019] [Indexed: 01/14/2023]
Abstract
Larger testes produce more sperm and therefore improve reproductive success in the face of sperm competition. Adaptation to social mating systems with relatively high and low sperm competition are therefore likely to have driven changes in relative testes size in opposing directions. Here, we combine the largest vertebrate testes mass dataset ever collected with phylogenetic approaches for measuring rates of morphological evolution to provide the first quantitative evidence for how relative testes mass has changed over time. We detect explosive radiations of testes mass diversity distributed throughout the vertebrate tree of life: bursts of rapid change have been frequent during vertebrate evolutionary history. In socially monogamous birds, there have been repeated rapid reductions in relative testes mass. We see no such pattern in other monogamous vertebrates; the prevalence of monogamy in birds may have increased opportunities for investment in alternative behaviours and physiologies allowing reduced investment in expensive testes.
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Affiliation(s)
- Joanna Baker
- School of Biological Sciences, University of Reading, Reading, RG6 6BX, UK
| | - Stuart Humphries
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, UK
| | - Henry Ferguson-Gow
- Department of Genetics, Evolution and Environment, Centre for Biodiversity and Environment Research, University College London, Gower Street, London, WC1E 6BT, UK
| | - Andrew Meade
- School of Biological Sciences, University of Reading, Reading, RG6 6BX, UK
| | - Chris Venditti
- School of Biological Sciences, University of Reading, Reading, RG6 6BX, UK
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34
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Zajitschek S, Zajitschek F, Josway S, Al Shabeeb R, Weiner H, Manier MK. Costs and benefits of giant sperm and sperm storage organs in
Drosophila melanogaster. J Evol Biol 2019; 32:1300-1309. [DOI: 10.1111/jeb.13529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/06/2019] [Accepted: 08/22/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Susanne Zajitschek
- Department of Biological Sciences George Washington University Washington DC USA
- School of Biological, Earth and Environmental Sciences University of New South Wales Sydney NSW Australia
| | - Felix Zajitschek
- Department of Biological Sciences George Washington University Washington DC USA
- School of Biological, Earth and Environmental Sciences University of New South Wales Sydney NSW Australia
| | - Sarah Josway
- Department of Biological Sciences George Washington University Washington DC USA
| | - Reem Al Shabeeb
- Department of Biological Sciences George Washington University Washington DC USA
| | - Halli Weiner
- Department of Biological Sciences George Washington University Washington DC USA
| | - Mollie K. Manier
- Department of Biological Sciences George Washington University Washington DC USA
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35
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Losdat S, Rojas Mora A, Bellut C, Chargé R, Falchi V, Glauser G, Vallat A, Helfenstein F. Social dominance, but not parasite load, affects sperm quality and sperm redox status in house sparrows. ACTA ACUST UNITED AC 2019; 222:jeb.200675. [PMID: 31439651 DOI: 10.1242/jeb.200675] [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: 01/30/2019] [Accepted: 08/11/2019] [Indexed: 12/19/2022]
Abstract
Sperm performance is an important component of male reproductive success. However, sperm production is costly and males need to optimize their investment in sperm quality versus the somatic traits involved in mating success, e.g. their social status. As oxidative stress affects both sperm performance and somatic functions, it has been hypothesized to mediate such a trade-off. According to the oxidation-based soma/germline trade-off hypothesis, dominant males should favour the antioxidant protection of their somatic tissues, and subordinate males should favour the antioxidant protection of their sperm. We tested this hypothesis by experimentally infecting wild-caught house sparrows Passer domesticus with Coccidia Isopora sp., an internal parasite known to deplete antioxidant resources. We predicted that (i) increased parasite load affects sperm oxidative status and sperm performance and that (ii) males with experimentally high parasite load adjust the antioxidant protection of their soma versus their sperm according to their social status. Despite a 5400% increase in parasite load, sperm performance and somatic and spermatic oxidative status remained unaffected, irrespective of male social status. Nevertheless, males increased their sperm performance over time, a pattern mirrored by an increase in the antioxidant protection of their sperm. Moreover, males at the lower end of the hierarchy always produced sperm of lower velocity, suggesting that they were constrained and privileged their soma over their germline. To conclude, high parasite loads do not necessarily affect sperm performance and oxidative status. In contrast, social hierarchy and the relative investment in soma versus sperm antioxidant protection are determinants of sperm performance.
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Affiliation(s)
- Sylvain Losdat
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Alfonso Rojas Mora
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Caroline Bellut
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Rémi Chargé
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Valentina Falchi
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Gaétan Glauser
- Neuchâtel Platform of Analytical Chemistry, Faculty of Sciences, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Armelle Vallat
- Neuchâtel Platform of Analytical Chemistry, Faculty of Sciences, University of Neuchâtel, 2000 Neuchâtel, Switzerland
| | - Fabrice Helfenstein
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland
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36
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Miller CW, Joseph PN, Kilner RM, Emberts Z. A weapons-testes trade-off in males is amplified in female traits. Proc Biol Sci 2019; 286:20190906. [PMID: 31362640 PMCID: PMC6710601 DOI: 10.1098/rspb.2019.0906] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/11/2019] [Indexed: 12/29/2022] Open
Abstract
Sexually selected weapons are assumed to trade off with traits related to ejaculates, such as testes. However, remarkably little is known about what governs resource allocation and why trade-offs are found in some cases and not others. Often-used models depict competitive allocation occurring within the functional grouping of traits (e.g. reproduction); however, other factors including tissue expense and developmental timing may influence allocation. Experimental comparisons of investment across the sexes have the potential to illuminate allocation rules, because the sexes do not always use traits for the same functions. Here, we capitalize upon a species where females have weapons-testes homologues. We report that a documented trade-off in investment between hind-limb weapons and testes in leaf-footed cactus bugs, Narnia femorata, is even more pronounced in female hind limbs and ovaries. Female hind limbs in this species do not share the clear reproductive function of male hind limbs; therefore, this trade-off spans trait functional groups. Such patterns of investment suggest that future studies of reproductive trade-offs should consider factors such as tissue expense and developmental timing.
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Affiliation(s)
- Christine W. Miller
- Entomology and Nematology Department, University of Florida, 1881 Natural Area Drive, Gainesville, FL 32611, USA
| | - Paul N. Joseph
- Entomology and Nematology Department, University of Florida, 1881 Natural Area Drive, Gainesville, FL 32611, USA
| | - Rebecca M. Kilner
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Zachary Emberts
- Department of Biology, University of Florida, 876 Newell Drive, Gainesville, FL 32611, USA
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37
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Friesen CR, de Graaf SP, Olsson M. The relationship of body condition, superoxide dismutase, and superoxide with sperm performance. Behav Ecol 2019. [DOI: 10.1093/beheco/arz086] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Abstract
Sperm competition theory predicts a negative correlation between somatic investment and traits that aid in pre- and postcopulatory sexual selection. Sperm performance is critical for postcopulatory success but sperm are susceptible to damage by free radicals such as superoxide radicals generated during mitochondrial respiration (mtSOx). Males can ameliorate damage to spermatozoa by investing in the production of antioxidants, like superoxide dismutase (SOD), which may act as a mechanistic link to pre- and postcopulatory trade-offs. Some male Australian, color-polymorphic painted dragon lizards (Ctenophorus pictus) possess a yellow throat patch (bib) that females prefer over nonbibbed males and are also more likely to win male–male contests indicating that males with bibs may be better at monopolizing females. We tested whether the sperm performance in nonbibbed males was superior to that of bibbed males. We show that overall sperm performance was not different between the bib-morphs, however, higher mtSOx levels were negatively correlated with sperm performance in bibbed males, but not of nonbibbed males. Blood cell mtSOx levels are negatively correlated with SOD activity in the plasma in all males early in the breeding season but SOD was lower in bibbed males. Nonbibbed males maintain a positive correlation between body condition and SOD activity over time while bibbed males do not. Together, these data suggest physiological associations between body condition, SOD activity, and sperm performance are linked to the expression of a yellow gular patch, which may be related to intrinsic differences in the metabolism of bibbed versus nonbibbed males.
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Affiliation(s)
- Christopher R Friesen
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Ross St. Camperdown, NSW Australia, Australia
| | - Simon P de Graaf
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Ross St. Camperdown, NSW Australia, Australia
| | - Mats Olsson
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia
- Department of Biological & Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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38
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Betty EL, Stockin KA, Smith ANH, Bollard B, Orams MB, Murphy S. Sexual maturation in male long-finned pilot whales (Globicephala melas edwardii): defining indicators of sexual maturity. J Mammal 2019. [DOI: 10.1093/jmammal/gyz086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Male reproductive biology is described for the Southern Hemisphere long-finned pilot whale (Globicephala melas edwardii), a subspecies that regularly mass strands along the New Zealand coastline. Ten mass stranding events sampled over a 7-year period enabled assessments of key life history parameters. Sexual maturation in immature, maturing, and mature males was assessed using morphological data and histological examination of testicular tissue. Variation was observed in the age (11–15 years) and length (450–490 cm) at which individuals attained sexual maturity. Using Bayesian cumulative logit regression models, we estimated the average age and length at the attainment of sexual maturity to be 13.5 years and 472 cm, respectively. Combined testes weight, combined testes length, an index of testicular development (combined testes weight/combined testes length), and mean seminiferous tubule diameter were all good indicators of sexual maturity status. Combined testes length was the best nonhistological indicator, and all testicular measures were found to be better indicators of sexual maturation for G. m. edwardii than age or total body length. Sexual maturity was attained before physical maturity (> 40 years and 570 cm), and at a younger age and smaller body length than previously reported for Globicephala melas melas in the North Atlantic. Given the ease of collection, minimal processing, and applicability to suboptimal material collected from stranding events, future studies should assess the value of testicular size as an indicator of sexual maturity in pilot whales and other cetacean species. Estimates of the average age and length at sexual maturity for G. m. edwardii provided in this study may be used to inform population models required for conservation management of the subspecies, which is subject to high levels of stranding-related mortality.
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Affiliation(s)
- Emma L Betty
- School of Natural and Computational Sciences, College of Sciences, Massey University, Auckland, New Zealand
- School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - Karen A Stockin
- School of Natural and Computational Sciences, College of Sciences, Massey University, Auckland, New Zealand
| | - Adam N H Smith
- School of Natural and Computational Sciences, College of Sciences, Massey University, Auckland, New Zealand
| | - Barbara Bollard
- School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - Mark B Orams
- School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
- Sustainability Research Centre, University of the Sunshine Coast, Queensland, Australia
| | - Sinéad Murphy
- Marine and Freshwater Research Centre, Department of Natural Sciences, School of Science and Computing, Galway-Mayo Institute of Technology, Galway, Ireland
- Institute of Zoology, Zoological Society of London, London, United Kingdom
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39
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Lüpold S, Simmons LW, Grueter CC. Sexual ornaments but not weapons trade off against testes size in primates. Proc Biol Sci 2019; 286:20182542. [PMID: 30966988 PMCID: PMC6501695 DOI: 10.1098/rspb.2018.2542] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 03/18/2019] [Indexed: 12/27/2022] Open
Abstract
Males must partition their limited reproductive investments between traits that promote access to females (sexual ornaments and weapons) and traits that enhance fertilization success, such as testes and ejaculates. Recent studies show that if the most weaponized males can monopolize access to females through contest competition, thereby reducing the risk of sperm competition, they tend to invest less in sperm production. However, how males invest in sexual ornaments relative to sperm production remains less clear. If male ornaments serve as badges of status, with high-ranking males attaining near-exclusive access to females, similar to monopolizing females through combat, their expression should also covary negatively with investment in post-mating traits. In a comparative study across primates, which exhibit considerable diversification in sexual ornamentation, male weaponry and testes size, we found relative testes size to decrease with sexual ornaments but increase with canine size. These contrasting evolutionary trajectories might be driven by differential selection, functional constraints or temporal patterns of metabolic investment between the different types of sexual traits. Importantly, however, our results indicate that the theory of relative investments between weapons and testes in the context of monopolizing females can extend to male ornaments.
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Affiliation(s)
- Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
| | - Leigh W. Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Cyril C. Grueter
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, Western Australia 6009, Australia
- School of Human Sciences (M309), The University of Western Australia, Crawley, Western Australia 6009, Australia
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40
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Meniri M, Gohon F, Gning O, Glauser G, Vallat A, Fasel NJ, Helfenstein F. Experimental manipulation of reproductive tactics in Seba's short-tailed bats: consequences on sperm quality and oxidative status. Curr Zool 2019; 65:609-616. [PMID: 31857807 PMCID: PMC6911846 DOI: 10.1093/cz/zoz011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/14/2019] [Indexed: 12/25/2022] Open
Abstract
To reproduce, males have to fertilize the female’s eggs, sometimes in competition with ejaculates of other males. In species where males display alternative reproductive tactics, whereby territorial males secure mating and non-territorial males have to sneak copulations, the latter might be expected to invest relatively more resources towards sperm quality compared with the territorial males. Sperm cells are especially vulnerable to oxidative stress, which reduces male fertility. Therefore, antioxidant resources are expected to modulate sperm quality, and might be allocated differently between reproductive tactics. To test the link between reproductive tactics, redox profile and sperm quality, we experimentally induced changes in the reproductive tactics of 39 captive males Seba’s short-tailed bats Carollia perspicillata. We monitored the blood and ejaculate oxidative balance, and the sperm quality before, 7 days and 21 days after the manipulation of reproductive tactic. Although ejaculates’ oxidative damage was negatively related to sperm velocity, males exhibited similar blood and ejaculates redox profiles and similar sperm quality, regardless of their reproductive tactic. Possibly, these results arise as a consequence of some constraints having been lifted during the experiment. Our results also suggest that, in Seba’s short-tailed bats, the expression of alternative reproductive tactics is not subjected to strong oxidative constraints. Furthermore, our results could reflect an absence of trade-off between pre- and post-copulatory traits in harem males, as they could be selected to invest both in female attraction and sperm quality, as a consequence of their inability to fully monopolize females.
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Affiliation(s)
- Magali Meniri
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, Switzerland
| | - Florence Gohon
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, Switzerland
| | - Ophélie Gning
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, Switzerland
| | - Gaétan Glauser
- Neuchatel Platform of Analytical Chemistry, University of Neuchâtel, Switzerland
| | - Armelle Vallat
- Neuchatel Platform of Analytical Chemistry, University of Neuchâtel, Switzerland
| | | | - Fabrice Helfenstein
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchâtel, Switzerland
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41
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Fox RJ, Fromhage L, Jennions MD. Sexual selection, phenotypic plasticity and female reproductive output. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180184. [PMID: 30966965 PMCID: PMC6365872 DOI: 10.1098/rstb.2018.0184] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2018] [Indexed: 01/17/2023] Open
Abstract
In a rapidly changing environment, does sexual selection on males elevate a population's reproductive output? If so, does phenotypic plasticity enhance or diminish any such effect? We outline two routes by which sexual selection can influence the reproductive output of a population: a genetic correlation between male sexual competitiveness and female lifetime reproductive success; and direct effects of males on females' breeding success. We then discuss how phenotypic plasticity of sexually selected male traits and/or female responses (e.g. plasticity in mate choice), as the environment changes, might influence how sexual selection affects a population's reproductive output. Two key points emerge. First, condition-dependent expression of male sexual traits makes it likely that sexual selection increases female fitness if reproductively successful males disproportionately transfer genes that are under natural selection in both sexes, such as genes for foraging efficiency. Condition-dependence is a form of phenotypic plasticity if some of the variation in net resource acquisition and assimilation is attributable to the environment rather than solely genetic in origin. Second, the optimal allocation of resources into different condition-dependent traits depends on their marginal fitness gains. As male condition improves, this can therefore increase or, though rarely highlighted, actually decrease the expression of sexually selected traits. It is therefore crucial to understand how condition determines male allocation of resources to different sexually selected traits that vary in their immediate effects on female reproductive output (e.g. ornaments versus coercive behaviour). In addition, changes in the distribution of condition among males as the environment shifts could reduce phenotypic variance in certain male traits, thereby reducing the strength of sexual selection imposed by females. Studies of adaptive evolution under rapid environmental change should consider the possibility that phenotypic plasticity of sexually selected male traits, even if it elevates male fitness, could have a negative effect on female reproductive output, thereby increasing the risk of population extinction. This article is part of the theme issue 'The role of plasticity in phenotypic adaptation to rapid environmental change'.
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Affiliation(s)
- Rebecca J. Fox
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Lutz Fromhage
- Department of Biological and Environmental Science, University of Jyvaskyla, PO Box 35, Jyvaskyla 40014, Finland
| | - Michael D. Jennions
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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42
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Vega‐Trejo R, Fox RJ, Iglesias‐Carrasco M, Head ML, Jennions MD. The effects of male age, sperm age and mating history on ejaculate senescence. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13305] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Regina Vega‐Trejo
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
- Department of Zoology Stockholm University Stockholm Sweden
| | - Rebecca J. Fox
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
| | - Maider Iglesias‐Carrasco
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
| | - Megan L. Head
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
| | - Michael D. Jennions
- Division of Ecology and Evolution, Research School of Biology Australian National University Canberra Australian Capital Territory Australia
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43
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Ge J, Wei J, Tao Y, Kang L. Sexual cooperation relies on food controlled by females in agromyzid flies. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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44
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Fox RJ, Gearing EE, Jennions MD, Head ML. Variation in the condition-dependence of individual sexual traits in male eastern mosquitofish, Gambusia holbrooki. Behav Ecol 2019. [DOI: 10.1093/beheco/arz002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Rebecca J Fox
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Michael D Jennions
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Megan L Head
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, ACT, Australia
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45
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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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46
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Supriya K, Price TD, Rowe M. Resource variation generates positive correlations between pre- and postcopulatory sexual traits. Behav Ecol 2018. [DOI: 10.1093/beheco/ary170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- K Supriya
- Committee on Evolutionary Biology, University of Chicago, Chicago, USA
| | - Trevor D Price
- Department of Ecology and Evolution, University of Chicago, Chicago, USA
| | - Melissah Rowe
- Natural History Museum, University of Oslo, Blindern, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Blindern, Oslo, Norway
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47
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McCambridge JE, Painting CJ, Walker LA, Holwell GI. Weapon allometry and phenotypic correlation in the New Zealand sheetweb spiderCambridgea plagiata. Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly170] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | - Leilani A Walker
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Gregory I Holwell
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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48
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Van den Beuken TPG, Duinmeijer CC, Smallegange IM. Costs of weaponry: Unarmed males sire more offspring than armed males in a male-dimorphic mite. J Evol Biol 2018; 32:153-162. [PMID: 30422392 PMCID: PMC7379726 DOI: 10.1111/jeb.13402] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 10/23/2018] [Accepted: 11/07/2018] [Indexed: 12/16/2022]
Abstract
Morphological structures used as weapons in male–male competition are not only costly to develop but are also probably costly to maintain during adulthood. Therefore, having weapons could reduce the energy available for other fitness‐enhancing actions, such as post‐copulatory investment. We tested the hypothesis that armed males make lower post‐copulatory investments than unarmed males, and that this difference will be most pronounced under food‐limited conditions. We performed two experiments using the male‐dimorphic bulb mite Rhizoglyphus robini, in which males are either armed “fighters” or unarmed “scramblers.” Firstly, we tested whether fighters and scramblers differed in their reproductive output after being starved or fed for 1 or 2 weeks. Secondly, we measured the reproductive output of scramblers and fighters (starved or fed) after one, two or three consecutive matings. Scramblers sired more offspring than fighters after 1 week, but scramblers and fighters only sired a few offspring after 2 weeks. Scramblers also sired more offspring than fighters at the first mating, and males rarely sired offspring after consecutive matings. Contrary to our hypothesis, the fecundity of starved and fed males did not differ. The higher reproductive output of scramblers suggests that, regardless of nutritional state, scramblers make larger post‐copulatory investments than fighters. Alternatively, (cryptic) female choice generally favours scramblers. Why the morphs differed in their reproductive output is unclear. Neither morph performed well relatively late in life or after multiple matings. It remains to be investigated to what extent the apparent scrambler advantage contributes to the maintenance and evolution of male morph expression.
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Affiliation(s)
- Tom P G Van den Beuken
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Chris C Duinmeijer
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Isabel M Smallegange
- Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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49
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Tuni C, Han CS, Dingemanse NJ. Multiple biological mechanisms result in correlations between pre- and post-mating traits that differ among versus within individuals and genotypes. Proc Biol Sci 2018; 285:rspb.2018.0951. [PMID: 30135156 DOI: 10.1098/rspb.2018.0951] [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: 04/27/2018] [Accepted: 07/26/2018] [Indexed: 11/12/2022] Open
Abstract
Reproductive traits involved in mate acquisition (pre-mating traits) are predicted to covary with those involved in fertilization success (post-mating traits). Variation in male quality may give rise to positive, and resource allocation trade-offs to negative, covariances between pre- and post-mating traits. Empirical studies have yielded mixed results. Progress is hampered as researchers often fail to appreciate that mentioned biological mechanisms can act simultaneously but at different hierarchical levels of biological variation: genetic correlations may, for example, be negative due to genetic trade-offs but environmental correlations may instead be positive due to individual variation in resource acquisition. We measured pre-mating (aggression, body weight) and post-mating (ejaculate size) reproductive traits in a pedigreed population of southern field crickets (Gryllus bimaculatus). To create environmental variation, crickets were raised on either a low or a high nymphal density treatment. We estimated genetic and environmental sources of correlations between pre- and post-mating traits. We found positive genetic correlations between pre- and post-mating traits, implying the existence of genetic variation in male quality. Over repeated trials of the same individual (testing order), positive changes in one trait were matched with negative changes in other traits, suggesting energy allocating trade-offs within individuals among days. These findings demonstrate the need for research on pre- and post-mating traits to consider the hierarchical structure of trait correlations. Only by doing so was our study able to conclude that multiple mechanisms jointly shape phenotypic associations between pre- and post-mating traits in crickets.
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Affiliation(s)
- Cristina Tuni
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
| | - Chang S Han
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany .,The School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Niels J Dingemanse
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich, Planegg-Martinsried, Germany
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50
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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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