1
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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2
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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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3
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Giannopoulos AS, Giannakou L, Gourgoulianni N, Pitaraki E, Jagirdar R, Marnas P, Tzamalas PI, Rouka E, Livanou E, Hatzoglou C, Gourgoulianis K, Lüpold S, Blanckenhorn WU, Zarogiannis SG. The effect of cigarette smoke extract exposure on the size and sexual behaviour of Drosophila melanogaster. Environ Toxicol Pharmacol 2023; 104:104325. [PMID: 37995887 DOI: 10.1016/j.etap.2023.104325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 11/20/2023] [Indexed: 11/25/2023]
Abstract
Drosophila melanogaster is a widely used animal model in human diseases and to date it has not been applied to the study of the impact of tobacco use on human sexual function. Hence, this report examines the effects of different concentrations of cigarette smoke extract (CSE) exposure on the size and sexual behavior of D. melanogaster. Wild-type flies were held in vials containing CSE-infused culture media at concentrations of 10%, 25%, and 50% for three days, and their offspring were reared under the same conditions before measuring their body size and mating behavior. CSE exposure during development reduced the tibia length and body mass of emerging adult flies and prolonged the time required for successful courtship copulation success, while courtship behaviors (wing extension, tapping, abdomen bending, attempted copulation) remained largely unchanged. Our findings indicate that CSE exposure negatively affects the development of flies and their subsequent reproductive success. Future experiments should investigate the CSE effect on male female fertility.
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Affiliation(s)
- Athanasios-Stefanos Giannopoulos
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Lydia Giannakou
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Natalia Gourgoulianni
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Eleanna Pitaraki
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Rajesh Jagirdar
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Periklis Marnas
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Panagiotis I Tzamalas
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Erasmia Rouka
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Eleni Livanou
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Chrissi Hatzoglou
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Konstantinos Gourgoulianis
- Department of Respiratory Medicine, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Wolf U Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Sotirios G Zarogiannis
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, 41500 Larissa, Greece.
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4
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Mahdjoub H, Khelifa R, Roy J, Sbilordo SH, Zeender V, Perdigón Ferreira J, Gourgoulianni N, Lüpold S. Interplay between male quality and male-female compatibility across episodes of sexual selection. Sci Adv 2023; 9:eadf5559. [PMID: 37774022 PMCID: PMC10541500 DOI: 10.1126/sciadv.adf5559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 08/30/2023] [Indexed: 10/01/2023]
Abstract
The processes underlying mate choice profoundly influence the dynamics of sexual selection and the evolution of male sexual traits. Consistent preference for certain phenotypes may erode genetic variation in populations through directional selection, whereas divergent preferences (e.g., genetically compatible mates) provide one mechanism to maintain such variation. However, the relative contributions of these processes across episodes of selection remain unknown. Using Drosophila melanogaster, we followed the fate of male genotypes, previously scored for their overall reproductive value and their compatibility with different female genotypes, across pre- and postmating episodes of selection. When pairs of competitor males differed in their intrinsic quality and their compatibility with the female, both factors influenced outcomes from mating success to paternity but to a varying degree between stages. These results add further dimensions to our understanding of how the interactions between genotypes and forms of selection shape reproductive outcomes and ultimately reproductive trait evolution.
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Affiliation(s)
- Hayat Mahdjoub
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Biology Department, Concordia University, 7141 Sherbrooke St. W., Montreal QC H4B 1R6, Canada
| | - Rassim Khelifa
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Biology Department, Concordia University, 7141 Sherbrooke St. W., Montreal QC H4B 1R6, Canada
| | - Jeannine Roy
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Sonja H. Sbilordo
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Valérian Zeender
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Jhoniel Perdigón Ferreira
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Natalia Gourgoulianni
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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5
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Zeender V, Pfammatter S, Roschitzki B, Dorus S, Lüpold S. Genotype-by-environment interactions influence the composition of the Drosophila seminal proteome. Proc Biol Sci 2023; 290:20231313. [PMID: 37700651 PMCID: PMC10498039 DOI: 10.1098/rspb.2023.1313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/09/2023] [Indexed: 09/14/2023] Open
Abstract
Ejaculate proteins are key mediators of post-mating sexual selection and sexual conflict, as they can influence both male fertilization success and female reproductive physiology. However, the extent and sources of genetic variation and condition dependence of the ejaculate proteome are largely unknown. Such knowledge could reveal the targets and mechanisms of post-mating selection and inform about the relative costs and allocation of different ejaculate components, each with its own potential fitness consequences. Here, we used liquid chromatography coupled with tandem mass spectrometry to characterize the whole-ejaculate protein composition across 12 isogenic lines of Drosophila melanogaster that were reared on a high- or low-quality diet. We discovered new proteins in the transferred ejaculate and inferred their origin in the male reproductive system. We further found that the ejaculate composition was mainly determined by genotype identity and genotype-specific responses to larval diet, with no clear overall diet effect. Nutrient restriction increased proteolytic protein activity and shifted the balance between reproductive function and RNA metabolism. Our results open new avenues for exploring the intricate role of genotypes and their environment in shaping ejaculate composition, or for studying the functional dynamics and evolutionary potential of the ejaculate in its multivariate complexity.
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Affiliation(s)
- Valérian Zeender
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
| | - Sibylle Pfammatter
- Functional Genomics Center Zurich, University of Zurich/ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Bernd Roschitzki
- Functional Genomics Center Zurich, University of Zurich/ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Steve Dorus
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
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6
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Zeender V, Sbilordo SH, Roy J, Lüpold S. Paternal condition affects offspring reproduction and life history in a sex-specific manner in Drosophila melanogaster. Evolution 2023; 77:467-481. [PMID: 36626809 DOI: 10.1093/evolut/qpac051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 11/21/2022] [Accepted: 12/06/2022] [Indexed: 01/12/2023]
Abstract
Nongenetic parental effects can contribute to the adaptation of species to changing environments by circumventing some of the limitations of genetic inheritance. A clearer understanding of the influence of nongenetic inheritance and its potentially sex-specific responses in daughters and sons is needed to better predict the evolutionary trajectories of species. However, whereas nongenetic maternal effects have long been recognized and widely studied, comparatively little is known about corresponding paternal effects. Here, by following 30 isogenic lines of Drosophila melanogaster across two generations, each reared under two dietary regimes in each generation, we tested how protein restriction during larval development of the fathers affects the fitness and health of their daughters and sons. We then quantified genetic and non-genetic paternal, and direct environmental, effects across multiple axes of offspring fitness. Daughters and sons responded differently to their father's developmental history. While isolines differed in mean trait values, their specific responses to protein restriction generally varied little. The sex- and trait-specific responses to paternal effects emphasize the complexity of inter-generational parental effects, which raise important questions about their mode of transmission and adaptive value, including the potential for conflict between the sexes.
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Affiliation(s)
- Valérian Zeender
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Sonja H Sbilordo
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Jeannine Roy
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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7
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Perdigón Ferreira J, Rohner PT, Lüpold S. Strongly sexually dimorphic forelegs are not more condition-dependent than less dimorphic traits in Drosophila prolongata. Evol Ecol 2023; 37:493-508. [PMID: 37152714 PMCID: PMC10156779 DOI: 10.1007/s10682-022-10226-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023]
Abstract
AbstractDirectional sexual selection drives the evolution of traits that are most closely linked to reproductive success, giving rise to trait exaggeration and sexual dimorphism. Exaggerated structures are often costly and, therefore, thought to be expressed in a condition-dependent manner. Sexual selection theory thus predicts a direct link between directional sexual selection, sexual dimorphism, and sex-specific condition dependence. However, only a handful of studies investigate the relationship between sexual dimorphism and condition dependence. Using 21 genetic lines of Drosophila prolongata, we here compared the degree of sexual dimorphism and sex-specific condition dependence, measured as allometric slopes, in sexually selected and non-sexual traits. Our data revealed male-biased sexual dimorphism in all traits examined, most prominently in the sexually selected forelegs. However, there was no relationship between the degree of sex-specific condition dependence and sexual dimorphism across traits and genetic lines. Our results contradict theoretical predictions and highlight the importance of understanding the role of exaggerated traits in the context of both sexual and natural selection.
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Affiliation(s)
- Jhoniel Perdigón Ferreira
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Patrick T. Rohner
- Department of Biology, Indiana University, 915 East Third Street, 102 Myers Hall, Bloomington, IN 47405 USA
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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8
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Laugen AT, Hosken DJ, Reinhold K, Schwarzenbach GA, Hoeck PEA, Bussière LF, Blanckenhorn WU, Lüpold S. Sperm competition in yellow dung flies: No consistent effect of sperm size. J Evol Biol 2022; 35:1309-1318. [PMID: 35972882 DOI: 10.1111/jeb.14073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/09/2022] [Accepted: 07/12/2022] [Indexed: 01/07/2023]
Abstract
The male competition for fertilization that results from female multiple mating promotes the evolution of increased sperm numbers and can impact sperm morphology, with theory predicting that longer sperm can at times be advantageous during sperm competition. If so, males with longer sperm should sire more offspring than competitors with shorter sperm. Few studies have directly tested this prediction, and findings are inconsistent. Here we assessed whether longer sperm provide a competitive advantage in the yellow dung fly (Scathophaga stercoraria; Diptera: Scathophagidae). Initially, we let brothers with different temperature-mediated mean sperm lengths compete - thus minimizing confounding effects of genetic background - and found no clear advantage of longer sperm. We then used flies from lines subjected to bidirectional selection on phenoloxidase activity that had shown correlated evolutionary responses in sperm and female spermathecal duct lengths. This experiment also yielded no main effect of sperm size on siring success. Instead, there was a trend for a shorter-sperm advantage, but only when competing in females with longer spermathecal ducts. Our data corroborated many previously reported findings (last-male precedence, effects of copula duration and body size), suggesting our failure to find sperm size effects is not inherently due to our experimental protocols. We conclude that longer sperm are not competitively superior in yellow dung flies under most circumstances, and that, consistent with previous work, in this species competitive fertilization success is primarily determined by the relative numbers of sperm competing.
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Affiliation(s)
- Ane T Laugen
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Centre for Coastal Research, Department of Natural Sciences, University of Agder, Kristiansand, Norway
| | - David J Hosken
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Centre for Ecology and Conservation, University of Exeter in Cornwall, Penryn, UK
| | - Klaus Reinhold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Evolutionsbiologie, Universität Bielefeld, Bielefeld, Germany
| | - Gioia A Schwarzenbach
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
| | - Paquita E A Hoeck
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
| | - Luc F Bussière
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Biology and Environmental Sciences, University of Gothenburg and Gothenburg Global Biodiversity Centre, Gothenburg, Sweden
| | - Wolf U Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
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9
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Liao WB, Jiang Y, Li DY, Jin L, Zhong MJ, Qi Y, Lüpold S, Kotrschal A. Cognition contra camouflage: How the brain mediates predator-driven crypsis evolution. Sci Adv 2022; 8:eabq1878. [PMID: 35977010 PMCID: PMC9385145 DOI: 10.1126/sciadv.abq1878] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 07/01/2022] [Indexed: 06/01/2023]
Abstract
While crypsis is a prominent antipredator adaptation, the role of the brain in predator-driven evolution remains controversial. Resolving this controversy requires contextualizing the brain with established antipredator traits and predation pressure. We hypothesize that the reduced predation risk through crypsis relaxes predation-driven selection on the brain and provide comparative evidence across 102 Chinese frog species for our hypothesis. Specifically, our phylogenetic path analysis reveals an indirect relationship between predation risk and crypsis that is mediated by brain size. This result suggests that at a low predation risk, frogs can afford to be conspicuous and use their large brain for cognitive predator evasion. This strategy may become less efficient or energetically costlier under higher predation pressure, favoring smaller brains and instead increasing crypsis.
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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, Sichuan, China
- Key Laboratory of Artificial Propagation and Utilization in Anurans of Nanchong City, China West Normal University, Nanchong, Sichuan, China
| | - Ying Jiang
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Da Yong Li
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Long Jin
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Mao Jun Zhong
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, Sichuan, China
| | - Yin Qi
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Alexander Kotrschal
- Behavioral Ecology, Department of Animal Sciences, Wageningen University, Wageningen, Netherlands
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10
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Rouka E, Gourgoulianni N, Lüpold S, Hatzoglou C, Gourgoulianis KI, Zarogiannis SG. Prediction and enrichment analyses of the Homo sapiens-Drosophila melanogaster COPD-related orthologs. Am J Physiol Regul Integr Comp Physiol 2021; 322:R77-R82. [PMID: 34877887 DOI: 10.1152/ajpregu.00092.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The significant similarities in airway epithelial cells between mammals and the fruit fly Drosophila melanogaster have rendered the latter an important model organism for studies of chronic inflammatory lung diseases. Focusing on the chronic obstructive pulmonary disease (COPD), we here mapped human gene orthologs associated with this disease in D. melanogaster to identify functionally equivalent genes for immediate, further screening with the fruit fly model. The DIOPT-DIST tool was accessed for the prediction of the COPD-associated orthologs between humans and Drosophila. Enrichment analyses with respect to pathways of the retrieved functional homologs were performed using the ToppFun and FlyMine tools, identifying 73 unique human genes as well as 438 fruit fly genes. The ToppFun analysis verified that the human gene list is associated with COPD phenotypes. Further, the FlyMine investigation highlighted that the Drosophila genes are functionally connected mainly with the 'ABC-family proteins mediated transport' and the 'beta-catenin independent WNT signaling pathway'. These results suggest an evolutionarily conserved role towards responses to inhaled toxicants and CO2 in both species. We reason that the predicted orthologous genes should be further studied in the Drosophila models of cigarette smoke-induced COPD.
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Affiliation(s)
- Erasmia Rouka
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece
| | - Natalia Gourgoulianni
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Chrissi Hatzoglou
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece.,Department of Respiratory Medicine, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece
| | - Konstantinos I Gourgoulianis
- Department of Respiratory Medicine, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece
| | - Sotirios G Zarogiannis
- Department of Physiology, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece.,Department of Respiratory Medicine, Faculty of Medicine, School of Health Sciences, University of Thessaly, BIOPOLIS, Larissa, Greece
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11
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Abstract
Abstract
Species with intense male–male competition for access to females often show alternative reproductive tactics (ARTs) where males of lower competitive ability adopt a sneaky behavior to gain access to mates. These ARTs are usually associated with intrasexual dimorphisms, in that males with distinct morphologies show different tactics. In some cases, however, males adopt different tactics without being dimorphic. Male Drosophila prolongata exhibit continuous variation in body size and shape, with enlarged forelegs that they use in male-male contests and in courtship, including stimulation of the female’s abdomen. During this “leg vibration,” however, nearby males can intercept the courted female and mate without their own courtship. Here, we studied the causes and consequences of these different mating tactics in competitive mating trials between males varying in their size and shape. We found that male mating tactics were condition-dependent. Whereas large, high-condition males were more likely to show leg vibration in their courtship, smaller, lower-condition males were more likely to intercept. However, the number of offspring produced was independent of male condition and reproductive tactic. We discuss possible scenarios for the evolution and maintenance of the ARTs and some future directions for the study of ARTs in this species and in general.
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Affiliation(s)
- Jhoniel Perdigón Ferreira
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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12
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Macartney EL, Zeender V, Meena A, De Nardo AN, Bonduriansky R, Lüpold S. Sperm depletion in relation to developmental nutrition and genotype in Drosophila melanogaster. Evolution 2021; 75:2830-2841. [PMID: 34617270 PMCID: PMC9297908 DOI: 10.1111/evo.14373] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 09/15/2021] [Accepted: 09/27/2021] [Indexed: 11/29/2022]
Abstract
Nutrient limitation during development can restrict the ability of adults to invest in costly fitness traits, and genotypes can vary in their sensitivity to developmental nutrition. However, little is known about how genotype and nutrition affect male ability to maintain ejaculate allocation and achieve fertilization across successive matings. Using 17 isogenic lines of Drosophila melanogaster, we investigated how variation in developmental nutrition affects males' abilities to mate, transfer sperm, and sire offspring when presented with successive virgin females. We found that, with each successive mating, males required longer to initiate copulation, transferred fewer sperm, and sired fewer offspring. Males reared on a low-nutrient diet transferred fewer sperm than those reared on nutritionally superior diets, but the rate at which males depleted their sperm, as well as their reproductive performance, was largely independent of diet. Genotype and the genotype × diet interaction explained little of the variation in these male reproductive traits. Our results show that sperm depletion can occur rapidly and impose substantial fitness costs for D. melanogaster males across multiple genotypes and developmental environments.
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Affiliation(s)
- Erin L Macartney
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
| | - Valérian Zeender
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
| | - Abhishek Meena
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland.,Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, 140306, India
| | - Alessio N De Nardo
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
| | - Russell Bonduriansky
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, CH-8057, Switzerland
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13
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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14
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Demont M, Ward PI, Blanckenhorn WU, Lüpold S, Martin OY, Bussière LF. How biases in sperm storage relate to sperm use during oviposition in female yellow dung flies. Behav Ecol 2021. [DOI: 10.1093/beheco/arab026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Abstract
Precise mechanisms underlying sperm storage and utilization are largely unknown, and data directly linking stored sperm to paternity remain scarce. We used competitive microsatellite PCR to study the effects of female morphology, copula duration and oviposition on the proportion of stored sperm provided by the second of two copulating males (S2) in Scathophaga stercoraria (Diptera: Scathophagidae), the classic model for sperm competition studies. We genotyped all offspring from potentially mixed-paternity clutches to establish the relationship between a second male’s stored sperm (S2) and paternity success (P2). We found consistent skew in sperm storage across the three female spermathecae, with relatively more second-male sperm stored in the singlet spermatheca than in the doublet spermathecae. S2 generally decreased with increasing spermathecal size, consistent with either heightened first-male storage in larger spermathecae, or less efficient sperm displacement in them. Additionally, copula duration and several two-way interactions influenced S2, highlighting the complexity of postcopulatory processes and sperm storage. Importantly, S2 and P2 were strongly correlated. Manipulation of the timing of oviposition strongly influenced observed sperm-storage patterns, with higher S2 when females laid no eggs before being sacrificed than when they oviposited between copulations, an observation consistent with adaptive plasticity in insemination. Our results identified multiple factors influencing sperm storage, nevertheless suggesting that the proportion of stored sperm is strongly linked to paternity (i.e., a fair raffle). Even more detailed data in this vein are needed to evaluate the general importance of sperm competition relative to cryptic female choice in postcopulatory sexual selection.
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Affiliation(s)
- Marco Demont
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel Winterthurerstrasse 190, Zurich, Switzerland
- Department of Biology and Institute of Integrative Biology, ETH Zurich, Universitätsstrasse 16, 8092 Zurich, Switzerland
| | - Paul I Ward
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel Winterthurerstrasse 190, Zurich, Switzerland
| | - Wolf U Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel Winterthurerstrasse 190, Zurich, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel Winterthurerstrasse 190, Zurich, Switzerland
| | - Oliver Y Martin
- Department of Biology and Institute of Integrative Biology, ETH Zurich, Universitätsstrasse 16, 8092 Zurich, Switzerland
| | - Luc F Bussière
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel Winterthurerstrasse 190, Zurich, Switzerland
- Biological and Environmental Sciences, University of Stirling, Stirling, Scotland, UK
- Biology and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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15
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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Rouka E, Gourgoulianni N, Lüpold S, Hatzoglou C, Gourgoulianis K, Blanckenhorn WU, Zarogiannis SG. The Drosophila septate junctions beyond barrier function: Review of the literature, prediction of human orthologs of the SJ-related proteins and identification of protein domain families. Acta Physiol (Oxf) 2021; 231:e13527. [PMID: 32603029 DOI: 10.1111/apha.13527] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 12/20/2022]
Abstract
The involvement of Septate Junctions (SJs) in critical cellular functions that extend beyond their role as diffusion barriers in the epithelia and the nervous system has made the fruit fly an ideal model for the study of human diseases associated with impaired Tight Junction (TJ) function. In this study, we summarized current knowledge of the Drosophila melanogaster SJ-related proteins, focusing on their unconventional functions. Additionally, we sought to identify human orthologs of the corresponding genes as well as protein domain families. The systematic literature search was performed in PubMed and Scopus databases using relevant key terms. Orthologs were predicted using the DIOPT tool and aligned protein regions were determined from the Pfam database. 3-D models of the smooth SJ proteins were built on the Phyre2 and DMPFold protein structure prediction servers. A total of 30 proteins were identified as relatives to the SJ cellular structure. Key roles of these proteins, mainly in the regulation of morphogenetic events and cellular signalling, were highlighted. The investigation of protein domain families revealed that the SJ-related proteins contain conserved domains that are required not only for cell-cell interactions and cell polarity but also for cellular signalling and immunity. DIOPT analysis of orthologs identified novel human genes as putative functional homologs of the fruit fly SJ genes. A gap in our knowledge was identified regarding the domains that occur in the proteins encoded by eight SJ-associated genes. Future investigation of these domains is needed to provide functional information.
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Affiliation(s)
- Erasmia Rouka
- Department of Physiology Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
| | - Natalia Gourgoulianni
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Chrissi Hatzoglou
- Department of Physiology Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
- Department of Respiratory Medicine Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
| | - Konstantinos Gourgoulianis
- Department of Respiratory Medicine Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
| | - Wolf U. Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Sotirios G. Zarogiannis
- Department of Physiology Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
- Department of Respiratory Medicine Faculty of Medicine School of Health Sciences University of ThessalyBIOPOLIS Larissa Greece
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17
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Lüpold S, de Boer RA, Evans JP, Tomkins JL, Fitzpatrick JL. How sperm competition shapes the evolution of testes and sperm: a meta-analysis. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200064. [PMID: 33070733 DOI: 10.1098/rstb.2020.0064] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Females of many species mate with multiple males, thereby inciting competition among ejaculates from rival males for fertilization. In response to increasing sperm competition, males are predicted to enhance their investment in sperm production. This prediction is so widespread that testes size (correcting for body size) is commonly used as a proxy of sperm competition, even in the absence of any other information about a species' reproductive behaviour. By contrast, a debate about whether sperm competition selects for smaller or larger sperm has persisted for nearly three decades, with empirical studies demonstrating every possible response. Here, we synthesize nearly 40 years of sperm competition research in a meta-analytical framework to determine how the evolution of sperm number (i.e. testes size) and sperm size (i.e. sperm head, midpiece, flagellum and total length) is influenced by varying levels of sperm competition across species. Our findings support the long-held assumption that higher levels of sperm competition are associated with relatively larger testes. We also find clear evidence that sperm competition is associated with increases in all components of sperm length. We discuss these results in the context of different theoretical predictions and general patterns in the breeding biology and selective environment of sperm. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Raïssa A de Boer
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, Stockholm 10691, Sweden
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences (M092), University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Joseph L Tomkins
- Centre for Evolutionary Biology, School of Biological Sciences (M092), University of Western Australia, Crawley, Western Australia 6009, Australia
| | - John L Fitzpatrick
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, Stockholm 10691, Sweden
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18
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Lüpold S, Reil JB, Manier MK, Zeender V, Belote JM, Pitnick S. How female × male and male × male interactions influence competitive fertilization in Drosophila melanogaster. Evol Lett 2020; 4:416-429. [PMID: 33014418 PMCID: PMC7523561 DOI: 10.1002/evl3.193] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/02/2020] [Accepted: 08/13/2020] [Indexed: 01/01/2023] Open
Abstract
How males and females contribute to joint reproductive success has been a long‐standing question in sexual selection. Under postcopulatory sexual selection, paternity success is predicted to derive from complex interactions among females engaging in cryptic female choice and males engaging in sperm competition. Such interactions have been identified as potential sources of genetic variation in sexually selected traits but are also expected to inhibit trait diversification. To date, studies of interactions between females and competing males have focused almost exclusively on genotypes and not phenotypic variation in sexually selected traits. Here, we characterize within‐ and between‐sex interactions in Drosophila melanogaster using isogenic lines with heritable variation in both male and female traits known to influence competitive fertilization. We confirmed, and expanded on, previously reported genotypic interactions within and between the sexes, and showed that several reproductive events, including sperm transfer, female sperm ejection, and sperm storage, were explained by two‐ and three‐way interactions among sex‐specific phenotypes. We also documented complex interactions between the lengths of competing males’ sperm and the female seminal receptacle, which are known to have experienced rapid female‐male co‐diversification. Our results highlight the nonindependence of sperm competition and cryptic female choice and demonstrate that complex interactions between the sexes do not limit the ability of multivariate systems to respond to directional sexual selection.
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Affiliation(s)
- Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich CH-8057 Switzerland.,Department of Biology Syracuse University Syracuse New York 13244
| | - Jonathan Bradley Reil
- Department of Entomology Cornell University Ithaca New York 14853.,Department of Plant and Environmental Protection Sciences University of Hawaii at Mānoa Honolulu Hawaii 96822
| | - Mollie K Manier
- Department of Biology Syracuse University Syracuse New York 13244.,Department of Biological Sciences George Washington University Washington DC 20052
| | - Valérian Zeender
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich CH-8057 Switzerland
| | - John M Belote
- Department of Biology Syracuse University Syracuse New York 13244
| | - Scott Pitnick
- Department of Biology Syracuse University Syracuse New York 13244
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19
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Mahdjoub H, Blanckenhorn WU, Lüpold S, Roy J, Gourgoulianni N, Khelifa R. Fitness consequences of the combined effects of veterinary and agricultural pesticides on a non-target insect. Chemosphere 2020; 250:126271. [PMID: 32114345 DOI: 10.1016/j.chemosphere.2020.126271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 06/10/2023]
Abstract
Pesticides and veterinary products that are globally used in farming against pests and parasites are known to impact non-target beneficial organisms. While most studies have tested the lethal and sub-lethal effects of single chemicals, species are exposed to multiple contaminants that might interact and exacerbate the toxic responses of life-history fitness components. Here we experimentally tested an ecotoxicological scenario that is likely to be widespread in nature, with non-target dung communities being exposed both to cattle parasiticides during the larval stage and to agricultural insecticides during their adult life. We assessed the independent and combined consumptive effects of varying ivermectin and spinosad concentration on juvenile life-history and adult reproductive traits of the widespread yellow dung fly (Scathophaga stercoraria; Diptera: Scathophagidae). Larval exposure to ivermectin prolonged development time and reduced egg-to-adult survival, body size, and the magnitude of the male-biased sexual size dimorphism. The consumption by the predatory adult flies of spinosad-contaminated prey showed an additional, independent (from ivermectin) negative effect on female clutch size, and subsequent egg hatching success, but not on the body size and sexual size dimorphism of their surviving offspring. However, there were interactive synergistic effects of both contaminants on offspring emergence and body size. Our results document adverse effects of the combination of different chemicals on fitness components of a dung insect, highlighting transgenerational effects of adult exposure to contaminants for their offspring. These findings suggest that ecotoxicological tests should consider the combination of different contaminants for more accurate eco-assessments.
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Affiliation(s)
- Hayat Mahdjoub
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Wolf U Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Jeannine Roy
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Natalia Gourgoulianni
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Rassim Khelifa
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland; Department of Botany, 2212 Main Mall, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada; Biodiversity Research Centre, 2212 Main Mall, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
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20
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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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21
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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22
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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23
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Lüpold S, Pitnick S. Sperm form and function: what do we know about the role of sexual selection? Reproduction 2018; 155:R229-R243. [DOI: 10.1530/rep-17-0536] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 02/19/2018] [Indexed: 12/20/2022]
Abstract
Sperm morphological variation has attracted considerable interest and generated a wealth of predominantly descriptive studies over the past three centuries. Yet, apart from biophysical studies linking sperm morphology to swimming velocity, surprisingly little is known about the adaptive significance of sperm form and the selective processes underlying its tremendous diversification throughout the animal kingdom. Here, we first discuss the challenges of examining sperm morphology in an evolutionary context and why our understanding of it is far from complete. Then, we review empirical evidence for how sexual selection theory applies to the evolution of sperm form and function, including putative secondary sexual traits borne by sperm.
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24
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Rohner PT, Teder T, Esperk T, Lüpold S, Blanckenhorn WU. The evolution of male‐biased sexual size dimorphism is associated with increased body size plasticity in males. Funct Ecol 2017. [DOI: 10.1111/1365-2435.13004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Patrick T. Rohner
- Department of Evolutionary Biology and Environmental StudiesUniversity of Zurich Zurich Switzerland
| | - Tiit Teder
- Department of ZoologyInstitute of Ecology and Earth SciencesUniversity of Tartu Tartu Estonia
- Department of EcologyFaculty of Environmental SciencesCzech University of Life Sciences Prague Praha 6 – Suchdol Czech Republic
| | - Toomas Esperk
- Department of Evolutionary Biology and Environmental StudiesUniversity of Zurich Zurich Switzerland
- Department of ZoologyInstitute of Ecology and Earth SciencesUniversity of Tartu Tartu Estonia
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental StudiesUniversity of Zurich Zurich Switzerland
| | - Wolf U. Blanckenhorn
- Department of Evolutionary Biology and Environmental StudiesUniversity of Zurich Zurich Switzerland
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Liao WB, Huang Y, Zeng Y, Zhong MJ, Luo Y, Lüpold S. Ejaculate evolution in external fertilizers: Influenced by sperm competition or sperm limitation? Evolution 2017; 72:4-17. [PMID: 28975611 DOI: 10.1111/evo.13372] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 12/19/2022]
Abstract
The evolution of sperm quality and quantity is shaped by various selective processes, with sperm competition generally considered the primary selective agent. Particularly in external fertilizers, however, sperm limitation through gamete dispersal can also influence gamete investments, but empirical data examining this effect are limited. Here, we studied the relative importance of sperm competition and the spawning conditions in explaining the macroevolutionary patterns of sperm size and number within two taxa with external fertilization but differences in their reproductive biology. In frogs, sperm swim slowly but for up to hours as they penetrate the gelatinous egg coating, whereas fish sperm typically swim fast, are very short-lived (seconds to minutes), and often face a relatively higher risk of being moved away from the ova by currents. Our phylogenetic models and path analyses revealed different trajectories of ejaculate evolution in these two taxa. Sperm size and number responded primarily to variation in sperm competition in the anurans, but more strongly to egg number and water turbulence in the fishes. Whereas the results across anurans align with the general expectation that sexual selection is the main driver of ejaculate evolution, our findings across the fishes suggest that sperm limitation has been underappreciated.
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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
| | - Yan Huang
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, Sichuan, China
| | - Yu Zeng
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), 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
| | - Yi Luo
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, Sichuan, China
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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26
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Simmons LW, Lüpold S, Fitzpatrick JL. Evolutionary Trade-Off between Secondary Sexual Traits and Ejaculates. Trends Ecol Evol 2017; 32:964-976. [PMID: 29050795 DOI: 10.1016/j.tree.2017.09.011] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 09/21/2017] [Accepted: 09/22/2017] [Indexed: 12/29/2022]
Abstract
Recent theoretical models predict that the evolutionary diversification of the weapons and ornaments of pre-mating sexual selection should be influenced by trade-offs with male expenditure on ejaculates. However, the patterns of association between secondary sexual traits and ejaculate expenditure are frequently inconsistent in their support of this prediction. We show why consideration of additional life-history, ecological, and mating-system variables is crucial for the interpretation of associations between secondary sexual traits and ejaculate production. Incorporation of these 'missing variables' provides evidence that interactions between pre- and post-mating sexual selection can underlie broad patterns of diversification in male weapons and ornaments. We call for more experimental and genetic approaches to uncover trade-offs, as well as for studies that consider the costs of mate-searching.
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Affiliation(s)
- Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia.
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - John L Fitzpatrick
- Department of Zoology and Ethology, Stockholm University, Svante Arrhenius väg 18B, SE-10691 Stockholm, Sweden
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27
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Lüpold S, Jin L, Liao WB. Population density and structure drive differential investment in pre- and postmating sexual traits in frogs. Evolution 2017; 71:1686-1699. [PMID: 28394412 DOI: 10.1111/evo.13246] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 03/25/2017] [Indexed: 01/01/2023]
Abstract
Sexual selection theory predicts a trade-off between premating (ornaments and armaments) and postmating (testes and ejaculates) sexual traits, assuming that growing and maintaining these traits is costly and that total reproductive investments are limited. The number of males in competition, the reproductive gains from investing in premating sexual traits, and the level of sperm competition are all predicted to influence how males allocate their finite resources to these traits. Yet, empirical examination of these predictions is currently scarce. Here, we studied relative expenditure on pre- and postmating sexual traits among frog species varying in their population density, operational sex ratio, and the number of competing males for each clutch of eggs. We found that the intensifying struggle to monopolize fertilizations as more and more males clasp the same female to fertilize her eggs shifts male reproductive investment toward sperm production and away from male weaponry. This shift, which is mediated by population density and the associated level of male-male competition, likely also explains the trade-off between pre- and postmating sexual traits in our much broader sample of anuran species. Our results highlight the power of such a multilevel approach in resolving the evolution of traits and allocation trade-offs.
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Affiliation(s)
- Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Long Jin
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, P. R. China
| | - Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, P. R. China
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28
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Abstract
Postcopulatory sexual selection is widely accepted to underlie the extraordinary diversification of sperm morphology. However, why does it favour longer sperm in some taxa but shorter in others? Two recent hypotheses addressing this discrepancy offered contradictory explanations. Under the sperm dilution hypothesis, selection via sperm density in the female reproductive tract favours more but smaller sperm in large, but the reverse in small, species. Conversely, the metabolic constraint hypothesis maintains that ejaculates respond positively to selection in small endothermic animals with high metabolic rates, whereas low metabolic rates constrain their evolution in large species. Here, we resolve this debate by capitalizing on the substantial variation in mammalian body size and reproductive physiology. Evolutionary responses shifted from sperm length to number with increasing mammalian body size, thus supporting the sperm dilution hypothesis. Our findings demonstrate that body-size-mediated trade-offs between sperm size and number can explain the extreme diversification in sperm phenotypes.
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Affiliation(s)
- Stefan Lüpold
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - John L Fitzpatrick
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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29
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Lüpold S, Manier MK, Puniamoorthy N, Schoff C, Starmer WT, Luepold SHB, Belote JM, Pitnick S. How sexual selection can drive the evolution of costly sperm ornamentation. Nature 2016; 533:535-8. [PMID: 27225128 DOI: 10.1038/nature18005] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/13/2016] [Indexed: 01/17/2023]
Abstract
Post-copulatory sexual selection (PSS), fuelled by female promiscuity, is credited with the rapid evolution of sperm quality traits across diverse taxa. Yet, our understanding of the adaptive significance of sperm ornaments and the cryptic female preferences driving their evolution is extremely limited. Here we review the evolutionary allometry of exaggerated sexual traits (for example, antlers, horns, tail feathers, mandibles and dewlaps), show that the giant sperm of some Drosophila species are possibly the most extreme ornaments in all of nature and demonstrate how their existence challenges theories explaining the intensity of sexual selection, mating-system evolution and the fundamental nature of sex differences. We also combine quantitative genetic analyses of interacting sex-specific traits in D. melanogaster with comparative analyses of the condition dependence of male and female reproductive potential across species with varying ornament size to reveal complex dynamics that may underlie sperm-length evolution. Our results suggest that producing few gigantic sperm evolved by (1) Fisherian runaway selection mediated by genetic correlations between sperm length, the female preference for long sperm and female mating frequency, and (2) longer sperm increasing the indirect benefits to females. Our results also suggest that the developmental integration of sperm quality and quantity renders post-copulatory sexual selection on ejaculates unlikely to treat male-male competition and female choice as discrete processes.
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Affiliation(s)
- Stefan Lüpold
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Mollie K Manier
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA.,Department of Biological Sciences, The George Washington University, 800 22nd St. NW, Suite 6000, Washington DC 20052, USA
| | - Nalini Puniamoorthy
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA.,Department of Biological Sciences, National University of Singapore, 14 Science Drive, SG 117543, Singapore
| | - Christopher Schoff
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA
| | - William T Starmer
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA
| | - Shannon H Buckley Luepold
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA
| | - John M Belote
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA
| | - Scott Pitnick
- Center for Reproductive Evolution, Department of Biology, Syracuse University, 107 College Place, Syracuse, New York 13244-1270, USA
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30
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McLennan HJ, Lüpold S, Smissen P, Rowe KC, Breed WG. Greater sperm complexity in the Australasian old endemic rodents (Tribe: Hydromyini) is associated with increased levels of inter-male sperm competition. Reprod Fertil Dev 2016; 29:RD15425. [PMID: 26922469 DOI: 10.1071/rd15425] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/08/2016] [Indexed: 12/12/2022] Open
Abstract
Spermatozoa exhibit considerable interspecies morphological variation across mammals, especially among murid rodents. In Australasia, most murids in the tribe Hydromyini have a spermatozoon with a highly complex head exhibiting an apical hook, characteristic of most murids, and two projections that extend from its upper concave surface, the ventral processes. In the present study we performed a phylogenetically controlled comparison of sperm morphology across 45 species of hydromyine rodents to test the hypothesis that the length and angle of both the apical hook and ventral processes, as well as the length of the sperm tail, increase with relative testes mass as a proxy for differences in levels of inter-male sperm competition. Although both sperm head protrusions exhibited considerable variation in their length and angle across species, only the angles increased significantly in relation to relative testes mass. Further, the length of the sperm flagellum was positively associated with relative testes mass. These results suggest that, in hydromyine rodents, the angle of the apical hook and ventral processes of the sperm head, as well as the sperm tail length, are likely to be sexually selected traits. The possible functional significance of these findings is briefly discussed.
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Lüpold S, Simmons LW, Tomkins JL, Fitzpatrick JL. No evidence for a trade-off between sperm length and male premating weaponry. J Evol Biol 2015; 28:2187-95. [PMID: 26332435 DOI: 10.1111/jeb.12742] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/24/2015] [Accepted: 08/25/2015] [Indexed: 01/15/2023]
Abstract
Male ornaments and armaments that mediate success in mate acquisition and ejaculate traits influencing competitive fertilization success are under intense sexual selection. However, relative investment in these pre- and post-copulatory traits depends on the relative importance of either selection episode and on the energetic costs and fitness gains of investing in these traits. Theoretical and empirical work has improved our understanding of how precopulatory sexual traits and investments in sperm production covary in this context. It has recently also been suggested that male weapon size may trade off with sperm length as another post-copulatory sexual trait, but the theoretical framework for this suggestion remains unclear. We evaluated the relationship between precopulatory armaments and sperm length, previously reported in ungulates, in five taxa as well as meta-analytically. Within and between taxa, we found no evidence for a negative or positive relationship between sperm length and male traits that are important in male-male contest competition. It is important to consider pre- and post-copulatory sexual selection together to understand fitness, and to study investments in different reproductive traits jointly rather than separately. A trade-off between pre- and post-copulatory sexual traits may not manifest itself in sperm length but rather in sperm number or function. Particularly in large-bodied taxa such as ungulates, sperm number is more variable interspecifically and likely to be under more intense selection than sperm length. We discuss our and the previous results in this context.
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Affiliation(s)
- S Lüpold
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester, UK.,Department of Biology, Life Sciences Complex, Syracuse University, Syracuse, NY, USA
| | - L W Simmons
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia
| | - J L Tomkins
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, Australia
| | - J L Fitzpatrick
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester, UK
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33
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Liu IA, Johndrow JE, Abe J, Lüpold S, Yasukawa K, Westneat DF, Nowicki S. Genetic diversity does not explain variation in extra-pair paternity in multiple populations of a songbird. J Evol Biol 2015; 28:1156-69. [PMID: 25876793 DOI: 10.1111/jeb.12644] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/03/2015] [Accepted: 04/08/2015] [Indexed: 11/28/2022]
Abstract
Many songbirds are socially monogamous but genetically polyandrous, mating with individuals outside their pair bonds. Extra-pair paternity (EPP) varies within and across species, but reasons for this variation remain unclear. One possible source of variation is population genetic diversity, which has been shown in interspecific meta-analyses to correlate with EPP but which has limited support from intraspecific tests. Using eight populations of the genetically polyandrous red-winged blackbird (Agelaius phoeniceus), including an island population, we investigated whether population-level differences in genetic diversity led to differences in EPP. We first measured genetic diversity over 10 microsatellite loci and found, as predicted, low genetic diversity in the island population. Additional structure analyses with multilocus genotypes and mtDNA showed the island population to be distinct from the continental populations. However, the island population's EPP rate fell in the middle of the continental populations' distribution, whereas the continental populations themselves showed significant variation in EPP. This result suggests that genetic diversity by itself is not a predictor of EPP rate. We discuss reasons for the departure from previous results, including hypotheses for EPP that do not solely implicate female-driven behaviour.
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Affiliation(s)
- I A Liu
- Department of Biology, Duke University, Durham, NC, USA
| | - J E Johndrow
- Department of Statistical Science, Duke University, Durham, NC, USA
| | - J Abe
- Department of Biology, Duke University, Durham, NC, USA
| | - S Lüpold
- Department of Biology, Syracuse University, Syracuse, NY, USA
| | - K Yasukawa
- Department of Biology, Beloit College, Beloit, WI, USA
| | - D F Westneat
- Department of Biology, University of Kentucky, Lexington, KY, USA
| | - S Nowicki
- Department of Biology, Duke University, Durham, NC, USA
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34
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35
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Lüpold S, Tomkins JL, Simmons LW, Fitzpatrick JL. Female monopolization mediates the relationship between pre- and postcopulatory sexual traits. Nat Commun 2014; 5:3184. [DOI: 10.1038/ncomms4184] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/31/2013] [Indexed: 11/09/2022] Open
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36
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Gress BE, Waltzer RJ, Lüpold S, Droge-Young EM, Manier MK, Pitnick S. Alternative mating tactics in the yellow dung fly: resolving mechanisms of small-male advantage off pasture. Proc Biol Sci 2014; 281:20132164. [PMID: 24225455 PMCID: PMC3843829 DOI: 10.1098/rspb.2013.2164] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/23/2013] [Indexed: 11/12/2022] Open
Abstract
Recent work suggests that the yellow dung fly mating system may include alternative patroller-competitor mating tactics in which large males compete for gravid females on dung, whereas small, non-competitive males search for females at foraging sites. Small males obtain most matings off pasture, yet the behavioural mechanism(s) giving rise to this pattern are unknown. We investigated the male and female behaviours that determine mating success in this environment by conducting field mating experiments and found small males to benefit from several attributes specific to the off-pasture mating environment. First, small males from foraging sites exhibited higher mating propensity, indicating that large males away from dung may be depleted of energy and/or sperm. Second, small males were more discriminating, being significantly less likely to attempt with non-gravid females, which are absent on dung but common off pasture. Third, non-gravid females were generally more likely to actively struggle and reject mating attempts; however, such behaviours occurred disproportionately more often with large males. Female Scathophaga stercoraria thus appear to preferentially mate with small males when off pasture. These findings challenge assumptions about male-female interactions in systems with alternative mating tactics and reveal hidden processes that may influence selection patterns in the field.
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Affiliation(s)
- Brian E. Gress
- Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA
| | - Ryan J. Waltzer
- Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA
| | - Stefan Lüpold
- Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA
| | | | - Mollie K. Manier
- Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA
- Department of Biological Sciences, The George Washington University, 2023 G Street, NW, Washington, DC 20052, USA
| | - Scott Pitnick
- Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA
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37
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Ala-Honkola O, Manier MK, Lüpold S, Droge-Young EM, Collins WF, Belote JM, Pitnick S. No inbreeding depression in sperm storage ability or offspring viability in Drosophila melanogaster females. J Insect Physiol 2014; 60:1-6. [PMID: 24188987 DOI: 10.1016/j.jinsphys.2013.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/21/2013] [Accepted: 10/23/2013] [Indexed: 06/02/2023]
Abstract
Mating between relatives usually decreases genetic quality of progeny as deleterious recessive alleles are expressed in inbred individuals. Inbreeding degrades sperm traits but its effects on sperm storage and fate within females are currently unknown. We quantified the relationship between the degrees of inbreeding relevant to natural populations (f=0, 0.25 and 0.50) and the number of sperm inseminated and stored, sperm swimming speed, long-term sperm viability while in storage, pattern of sperm precedence, mating latency, and offspring viability of female Drosophila melanogaster. The use of transgenic flies that have either red or green fluorescent sperm heads allowed us to distinguish two ejaculates in the female reproductive tract and facilitated quantification of sperm storage and use traits. We found no inbreeding depression in either long- or short-term sperm storage ability. The most inbred females exhibited significantly longer mating latency, which could be explained by males preferring to mate with outbred females. On the other hand, as no evidence for cryptic male choice in the form of ejaculate tailoring of sperm number was found, the most inbred females might just be less eager to mate. We also found no evidence that the degree of maternal inbreeding influenced offspring viability. Comparison with a contemporaneous study of male inbreeding consequences for ejaculate quality suggests that inbreeding depression is more severe in males than in females in our study population.
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Affiliation(s)
- Outi Ala-Honkola
- Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, 40014, Finland; Department of Biology, Syracuse University, Syracuse, NY 13244, USA.
| | - Mollie K Manier
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA; The George Washington University, Biological Sciences, 2023 G St. NW, Washington, DC 20052, USA.
| | - Stefan Lüpold
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA.
| | | | - William F Collins
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA.
| | - John M Belote
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA.
| | - Scott Pitnick
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA.
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Manier MK, Lüpold S, Belote JM, Starmer WT, Berben KS, Ala-Honkola O, Collins WF, Pitnick S. Postcopulatory sexual selection generates speciation phenotypes in Drosophila. Curr Biol 2013; 23:1853-62. [PMID: 24076241 DOI: 10.1016/j.cub.2013.07.086] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 07/31/2013] [Accepted: 07/31/2013] [Indexed: 01/29/2023]
Abstract
BACKGROUND Identifying traits that reproductively isolate species, and the selective forces underlying their divergence, is a central goal of evolutionary biology and speciation research. There is growing recognition that postcopulatory sexual selection, which can drive rapid diversification of interacting ejaculate and female reproductive tract traits that mediate sperm competition, may be an engine of speciation. Conspecific sperm precedence (CSP) is a taxonomically widespread form of reproductive isolation, but the selective causes and divergent traits responsible for CSP are poorly understood. RESULTS To test the hypothesis that postcopulatory sexual selection can generate reproductive isolation, we expressed GFP or RFP in sperm heads of recently diverged sister species, Drosophila simulans and D. mauritiana, to enable detailed resolution of species-specific sperm precedence mechanisms. Between-species divergence in sperm competition traits and mechanisms prompted six a priori predictions regarding mechanisms of CSP and degree of cross asymmetry in reproductive isolation. We resolved four distinct mechanisms of CSP that were highly consistent with predictions. These comprise interactions between multiple sex-specific traits, including two independent mechanisms by which females exert sophisticated control over sperm fate to favor the conspecific male. CONCLUSIONS Our results confirm that reproductive isolation can quickly arise from diversifying (allopatric) postcopulatory sexual selection. This experimental approach to "speciation phenotypes" illustrates how knowledge of sperm precedence mechanisms can be used to predict the mechanisms and extent of reproductive isolation between populations and species.
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Affiliation(s)
- Mollie K Manier
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
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39
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Manier MK, Lüpold S, Pitnick S, Starmer WT. An analytical framework for estimating fertilization bias and the fertilization set from multiple sperm-storage organs. Am Nat 2013; 182:552-61. [PMID: 24021407 DOI: 10.1086/671782] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
How sperm from competing males are used to fertilize eggs is poorly understood yet has important implications for postcopulatory sexual selection. Sperm may be used in direct proportion to their numerical representation within the fertilization set or with a bias toward one male over another. Previous theoretical treatments have assumed a single sperm-storage organ, but many taxa possess multiple organs or store sperm within multiple regions of the reproductive tract. In Drosophila, females store sperm in two distinct storage organ types: the seminal receptacle (SR) and the paired spermathecae. Here, we expand previous "raffle" models to describe "fertilization bias" independently for sperm within the SR and the spermathecae and estimate the fertilization set based on the relative contribution of sperm from the different sperm-storage organ types. We apply this model to three closely related species to reveal rapid divergence in the fertilization set and the potential for female sperm choice.
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Affiliation(s)
- Mollie K Manier
- Department of Biology, Syracuse University, Syracuse, New York 13244
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40
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Ala-Honkola O, Hosken DJ, Manier MK, Lüpold S, Droge-Young EM, Berben KS, Collins WF, Belote JM, Pitnick S. Inbreeding reveals mode of past selection on male reproductive characters in Drosophila melanogaster. Ecol Evol 2013; 3:2089-102. [PMID: 23919154 PMCID: PMC3728949 DOI: 10.1002/ece3.625] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 01/22/2023] Open
Abstract
Directional dominance is a prerequisite of inbreeding depression. Directionality arises when selection drives alleles that increase fitness to fixation and eliminates dominant deleterious alleles, while deleterious recessives are hidden from it and maintained at low frequencies. Traits under directional selection (i.e., fitness traits) are expected to show directional dominance and therefore an increased susceptibility to inbreeding depression. In contrast, traits under stabilizing selection or weakly linked to fitness are predicted to exhibit little-to-no inbreeding depression. Here, we quantify the extent of inbreeding depression in a range of male reproductive characters and then infer the mode of past selection on them. The use of transgenic populations of Drosophila melanogaster with red or green fluorescent-tagged sperm heads permitted in vivo discrimination of sperm from competing males and quantification of characteristics of ejaculate composition, performance, and fate. We found that male attractiveness (mating latency) and competitive fertilization success (P2) both show some inbreeding depression, suggesting they may have been under directional selection, whereas sperm length showed no inbreeding depression suggesting a history of stabilizing selection. However, despite having measured several sperm quality and quantity traits, our data did not allow us to discern the mechanism underlying the lowered competitive fertilization success of inbred (f = 0.50) males.
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Affiliation(s)
- Outi Ala-Honkola
- Department of Biology, Syracuse University Syracuse, New York ; Department of Biological and Environmental Science, University of Jyväskylä PO Box 35, 40014, Finland
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Manier MK, Belote JM, Berben KS, Lüpold S, Ala-Honkola O, Collins WF, Pitnick S. Rapid diversification of sperm precedence traits and processes among three sibling Drosophila species. Evolution 2013; 67:2348-62. [PMID: 23888856 DOI: 10.1111/evo.12117] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/12/2013] [Indexed: 01/13/2023]
Abstract
Postcopulatory sexual selection is credited with driving rapid evolutionary diversification of reproductive traits and the formation of reproductive isolating barriers between species. This judgment, however, has largely been inferred rather than demonstrated due to general lack of knowledge about processes and traits underlying variation in competitive fertilization success. Here, we resolved processes determining sperm fate in twice-mated females, using transgenic Drosophila simulans and Drosophila mauritiana populations with fluorescently labeled sperm heads. Comparisons among these two species and Drosophila melanogaster revealed a shared motif in the mechanisms of sperm precedence, with postcopulatory sexual selection potentially occurring during any of the three discrete stages: (1) insemination; (2) sperm storage; and (3) sperm use for fertilization, and involving four distinct phenomena: (1) sperm transfer; (2) sperm displacement; (3) sperm ejection; and (4) sperm selection for fertilizations. Yet, underlying the qualitative similarities were significant quantitative differences in nearly every relevant character and process. We evaluate these species differences in light of concurrent investigations of within-population variation in competitive fertilization success and postmating/prezygotic reproductive isolation in hybrid matings between species to forge an understanding of the relationship between microevolutionary processes and macroevolutionary patterns as pertains to postcopulatory sexual selection in this group.
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Affiliation(s)
- Mollie K Manier
- Department of Biology, Syracuse University, Syracuse, New York 13244, USA
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Lüpold S. Ejaculate quality and constraints in relation to sperm competition levels among eutherian mammals. Evolution 2013; 67:3052-60. [PMID: 24094354 DOI: 10.1111/evo.12132] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Accepted: 04/05/2013] [Indexed: 01/21/2023]
Abstract
The outcome of sperm competition is influenced by the relative quantity and quality of sperm among competing ejaculates. Whereas it is well established that individual ejaculate traits evolve rapidly under postcopulatory sexual selection, little is known about other factors that might influence the evolution of ejaculates. For example, the metabolic rate is likely to affect the sperm production rate and the cellular activity or metabolism of sperm, and it has recently been suggested to constrain the evolution of sperm length in large but not small mammals. I thus examined in eutherian mammals how ejaculate quality traits vary with one another and with testis mass, body size, and metabolism. I found all ejaculate traits to covary positively with one another and to increase with relative testis mass. When controlling for testis mass, small-bodied species showed superior sperm quality (but not sperm number). Furthermore, sperm motility and viability were positively associated with the mass-corrected metabolic rate, but the percentage of morphologically normal and acrosome-intact sperm were not. These results indicate that body size and the energy budget may also influence the evolution of ejaculate quality, although these influences appear to vary among traits.
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Affiliation(s)
- Stefan Lüpold
- Department of Biology, Life Sciences Complex, 107 College Place, Syracuse University, Syracuse, New York, 13244.
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Lüpold S, Birkhead TR, Westneat DF. Seasonal variation in ejaculate traits of male red-winged blackbirds (Agelaius phoeniceus). Behav Ecol Sociobiol 2012. [DOI: 10.1007/s00265-012-1415-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lüpold S, Manier MK, Berben KS, Smith KJ, Daley BD, Buckley SH, Belote JM, Pitnick S. How multivariate ejaculate traits determine competitive fertilization success in Drosophila melanogaster. Curr Biol 2012; 22:1667-72. [PMID: 22840512 DOI: 10.1016/j.cub.2012.06.059] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 05/18/2012] [Accepted: 06/21/2012] [Indexed: 11/19/2022]
Abstract
Success in sperm competition, occurring whenever females mate with multiple males, is predicted to be influenced by variation in ejaculate quality and interactions among competing sperm. Yet, apart from sperm number, relevant ejaculate characteristics and sperm-sperm interactions are poorly understood, particularly within a multivariate framework and the natural selective environment of the female reproductive tract. Here, we used isogenic lines of Drosophila melanogaster with distinguishable sperm to demonstrate and partition genetic variation in multiple sperm quality and performance traits. Next, by competing males from different lines, we show how rival sperm significantly influence each other's velocity and reveal that males with relatively slow and/or long sperm better displace rival sperm and resist displacement, thus avoiding ejection by the female from her reproductive tract. Finally, we establish fitness consequences of genetic variation in sperm quality and its role in securing a numerical advantage in storage by showing that offspring paternity is determined strictly by the representation of stored, competing sperm. These results provide novel insight into complex postcopulatory processes, illustrate that different ejaculate traits are critical at different biologically relevant time-points, and provide a critical foundation for elucidating the role of postcopulatory sexual selection in trait diversification and speciation.
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Affiliation(s)
- Stefan Lüpold
- Department of Biology, Syracuse University, Syracuse, NY 13244-1270, USA.
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Lüpold S. They produce the sperm, but whose is it?: The 11 Biology of Spermatozoa Meeting September 5-9, 2011-Derbyshire UK. Spermatogenesis 2012; 1:339-340. [PMID: 22332117 DOI: 10.4161/spmg.1.4.18327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 10/01/2011] [Indexed: 11/19/2022]
Abstract
Sperm biology pervades numerous research areas from clinical research to evolutionary biology and animal conservation. Integrating these fields for a better understanding of each is one of the main goals of the Biology of Spermatozoa meeting, a conference held biennially outside of Sheffield in the United Kingdom. This September, at the 11th meeting, scientists from around the globe presented their ongoing research on numerous aspects of reproductive biology, from assisted reproduction in humans and animal conservation through stem cell research and proteomics to sophisticated evolutionary adaptations of ejaculates and female reproductive traits in order to bias paternity toward one or the other male in situations of female promiscuity. Throughout the conference, ethical controversies with reproductive applications (e.g., sperm banking) found their place just as much as novel clinical technologies (e.g., sperm quality assays) or major advances in understanding the mechanisms underlying fundamental processes of postcopulatory sexual selection (e.g., using transgenic animals that produce fluorescently labeled sperm). Across a wide range of different taxa, this meeting has presented a fascinating synthesis of current research and emerging directions in the study of sperm biology.
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Affiliation(s)
- Stefan Lüpold
- Department of Biology; Life Sciences Complex; Syracuse University; Syracuse, NY USA
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Abstract
Selection to avoid inbreeding is predicted to vary across species due to differences in population structure and reproductive biology. Over the past decade, there have been numerous investigations of postcopulatory inbreeding avoidance, a phenomenon that first requires discrimination of mate (or sperm) relatedness and then requires mechanisms of male ejaculate tailoring and/or cryptic female choice to avoid kin. The number of studies that have found a negative association between male-female genetic relatedness and competitive fertilization success is roughly equal to the number of studies that have not found such a relationship. In the former case, the underlying mechanisms are largely unknown. The present study was undertaken to verify and expand upon a previous report of postcopulatory inbreeding avoidance in D. melanogaster, as well as to resolve underlying mechanisms of inbreeding avoidance using transgenic flies that express a sperm head-specific fluorescent tag. However, siblings did not have a lower fertilization success as compared to unrelated males in either the first (P(1) ) or second (P(2) ) mate role in sperm competition with a standard unrelated competitor male in our study population of D. melanogaster. Analyses of mating latency, copulation duration, egg production rate, and remating interval further revealed no evidence for inbreeding avoidance.
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Affiliation(s)
- Outi Ala-Honkola
- Department of Biology, Syracuse University, Syracuse, New York 13244-1270, USA.
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Lüpold S, Wistuba J, Damm OS, Rivers JW, Birkhead TR. Sperm competition leads to functional adaptations in avian testes to maximize sperm quantity and quality. Reproduction 2011; 141:595-605. [PMID: 21307271 DOI: 10.1530/rep-10-0501] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The outcome of sperm competition (i.e. competition for fertilization between ejaculates from different males) is primarily determined by the relative number and quality of rival sperm. Therefore, the testes are under strong selection to maximize both sperm number and quality, which are likely to result in trade-offs in the process of spermatogenesis (e.g. between the rate of spermatogenesis and sperm length or sperm energetics). Comparative studies have shown positive associations between the level of sperm competition and both relative testis size and the proportion of seminiferous (sperm-producing) tissue within the testes. However, it is unknown how the seminiferous tissue itself or the process of spermatogenesis might evolve in response to sperm competition. Therefore, we quantified the different germ cell types and Sertoli cells (SC) in testes to assess the efficiency of sperm production and its associations with sperm length and mating system across 10 species of New World Blackbirds (Icteridae) that show marked variation in sperm length and sperm competition level. We found that species under strong sperm competition generate more round spermatids (RS)/spermatogonium and have SC that support a greater number of germ cells, both of which are likely to increase the maximum sperm output. However, fewer of the RS appeared to elongate to mature spermatozoa in these species, which might be the result of selection for discarding spermatids with undesirable characteristics as they develop. Our results suggest that, in addition to overall size and gross morphology, testes have also evolved functional adaptations to maximize sperm quantity and quality.
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Affiliation(s)
- Stefan Lüpold
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
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Abstract
Sperm velocity is one of the main determinants of the outcome of sperm competition. Since sperm vary considerably in their morphology between and within species, it seems likely that sperm morphology is associated with sperm velocity. Theory predicts that sperm velocity may be increased by enlarged midpiece (energetic component) or flagellum length (kinetic component), or by particular ratios between sperm components, such as between flagellum length and head size. However, such associations have rarely been found in empirical studies. In a comparative framework in passerine birds, we tested these theoretical predictions both across a wide range of species and within a single family, the New World blackbirds (Icteridae). In both study groups, sperm velocity was influenced by sperm morphology in the predicted direction. Consistent with theoretical models, these results show that selection on sperm morphology and velocity are likely to be concomitant evolutionary forces.
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Affiliation(s)
- Stefan Lüpold
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
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Abstract
Sperm morphology varies considerably across taxa, and postcopulatory sexual selection is thought to be one of the main forces responsible for this diversity. Several studies have investigated the effects of the variation in sperm design on sperm function, but the consequences of variation in sperm design on testis morphology have been overlooked. Testes size or architecture may determine the size of the sperm they produce, and selection for longer sperm may require concomitant adaptations in the testes. Relative testes size differs greatly between species and is often used as an index of sperm competition, but little is known about whether larger testes have more sperm-producing tissue or produce sperm at a faster rate. Using a comparative approach in New World Blackbirds (Icteridae), we found (1) a strong link between testis histology and sperm length, suggesting selection on testis architecture through selection on sperm size, and (2) that species under intense sperm competition had a greater proportion of sperm-producing tissue within their testes. These results support the prediction that sperm competition fosters adaptations in reproductive organs that extend beyond testes size, and raise questions about the trade-offs influencing reproductive investment.
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Affiliation(s)
- Stefan Lüpold
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom.
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