1
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Friesen CR, Uhrig EJ, Mason RT. Dehydrated males are less likely to dive into the mating pool. Behav Ecol 2021. [DOI: 10.1093/beheco/arab151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Abstract
The hydration state of animals vying for reproductive success may have implications for the tempo and mode of sexual selection, which may be salient in populations that experience increasing environmental fluctuations in water availability. Using red-sided garter snakes as a model system, we tested the effect of water supplementation on courtship, mating behavior, and copulatory plug (CP) production during a drought year. Over 3 days of mating trials, water-supplemented males (WET males, n = 45) outperformed a control group that was not supplemented with water (DRY males, n = 45). Over 70% of WET males mated but just 33% of DRY males did so. As a group, WET males mated 79 times versus 28 times by DRY males. On the last day of mating trials, over 70% of WET males were still courting, with 19 of them mating, whereas less than 25% of DRY males were courting and only one mated. CP deposition accounted for 4–6% of the mass lost by mating males, but hydration did not affect CP mass or water content. These findings suggest that, in years of low water availability, the number of courting males and the intensity of their courtship declines, thereby affecting sexual selection and conflict, at least within that year.
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Affiliation(s)
- Christopher R Friesen
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Building 35, Northfields Avenue, Wollongong, NSW 2522, Australia
- Department of Integrative Biology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
- School of Life and Environmental Sciences, Bldg F22, Life Earth and Environmental Sciences (LEES) Building, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Emily J Uhrig
- Department of Integrative Biology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
- Center for Research on Sustainable Forests, University of Maine, 5755 Nutting Hall, Room 263, Orono, ME 04469, USA
| | - Robert T Mason
- Department of Integrative Biology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331, USA
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2
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Gangloff EJ, Manes MB, Schwartz TS, Robert KA, Huebschman N, Bronikowski AM. Multiple paternity in garter snakes with evolutionarily divergent life-histories. J Hered 2021; 112:508-518. [PMID: 34351393 PMCID: PMC8558580 DOI: 10.1093/jhered/esab043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 08/04/2021] [Indexed: 11/25/2022] Open
Abstract
Many animal species exhibit multiple paternity, defined as multiple males genetically contributing to a single female reproductive event, such as a clutch or litter. Although this phenomenon is well documented across a broad range of taxa, the underlying causes and consequences remain poorly understood. For example, it is unclear how multiple paternity correlates with life-history strategies. Furthermore, males and females may differ in mating strategies and these patterns may shift with ecological context and life-history variation. Here, we take advantage of natural life-history variation in garter snakes (Thamnophis elegans) to address these questions in a robust field setting where populations have diverged along a slow-to-fast life-history continuum. We determine both female (observed) and male (using molecular markers) reproductive success in replicate populations of 2 life-history strategies. We find that despite dramatic differences in annual female reproductive output: 1) females of both life-history ecotypes average 1.5 sires per litter and equivalent proportions of multiply-sired litters, whereas 2) males from the slow-living ecotype experience greater reproductive skew and greater variance in reproductive success relative to males from the fast-living ecotype males despite having equivalent average reproductive success. Together, these results indicate strong intrasexual competition among males, particularly in the fast-paced life-history ecotype. We discuss these results in the context of competing hypotheses for multiple paternity related to population density, resource variability, and life-history strategy.
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Affiliation(s)
- Eric J Gangloff
- Dept. of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011 USA.,Department of Zoology, Ohio Wesleyan University, Delaware, OH USA
| | - Megan B Manes
- Dept. of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011 USA
| | - Tonia S Schwartz
- Dept. of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011 USA.,Deptartment of Biological Sciences, Auburn University, Auburn, AL 36849 USA
| | - Kylie A Robert
- Dept. of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011 USA.,Deptartment of Ecology, Environment & Evolution, La Trobe University, Bundoora, Victoria 3086 Australia
| | | | - Anne M Bronikowski
- Dept. of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011 USA
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3
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Friesen CR, Mason RT, Uhrig EJ. Postcopulatory sexual selection as a driver of sex- and population-specific kidney mass in garter snakes? Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Abstract
In lizards and snakes, the kidneys produce seminal fluid in addition to having osmoregulatory functions. Therefore, in response to polyandry, kidney mass should be under selection regimes such as those influencing testes. Male red-sided garter snakes deposit a kidney-derived copulatory plug that functions in sperm competition. We first tested for intersexual differences in kidney mass and allometry in one population and found that males had kidneys twice as heavy as those of females, consistent with stronger selection on male kidney mass. Previous studies have shown that male size enhances mating success in one-on-one competition prevalent in small mating aggregations. We then examined the relationship between body size, kidney mass and testes mass in two populations with low (LD) and high (HD) mating aggregation densities. Males from the HD population had heavier testes and heavier kidneys compared with males from the LD population; HD males were also smaller in body size. Our results suggest that the strength of sexual selection, and possibly the balance between pre- and postcopulatory selection, varies in response to population size or density. However, more replication is needed to confirm the generality of these results within red-sided garter snakes and other squamate reptiles.
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Affiliation(s)
- Christopher R Friesen
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Robert T Mason
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Emily J Uhrig
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
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4
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Friesen CR, Kahrl AF, Olsson M. Sperm competition in squamate reptiles. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200079. [PMID: 33070739 DOI: 10.1098/rstb.2020.0079] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Multiple paternity is ubiquitous within the polyphyletic group called 'reptiles', especially within the lizards and snakes. Therefore, the probability of sperm competition occurring, and being intense, is high. Squamates exhibit a diversity of tactics to ensure fertilization success in the face of sperm competition. The duration of female sperm storage, which can be many months and even years in some species, remains an enigma. Here, we emphasize some mechanisms that might affect patterns of paternity, the source and function of ejaculates and features of the female reproductive tract that may aid in long-term sperm storage. In doing so, we present a new analysis of the relationship between sperm size, the strength of sperm competition and the duration of female sperm storage. Lizards and snakes are a diverse group that has provided many excellent models for the study of an array of life-history strategies. However, when it comes to postcopulatory sexual selection, there is much left to discover. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Christopher R Friesen
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.,Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Ariel F Kahrl
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Mats Olsson
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.,Department of Biological and Environmental Science, University of Gothenburg, Goteborg, Sweden
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5
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Rollings N, Waye HL, Krohmer RW, Uhrig EJ, Mason RT, Olsson M, Whittington CM, Friesen CR. Sperm telomere length correlates with blood telomeres and body size in red‐sided garter snakes,
Thamnophis sirtalis parietalis. J Zool (1987) 2020. [DOI: 10.1111/jzo.12789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- N. Rollings
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - H. L. Waye
- Division of Science and Mathematics University of Minnesota Morris Morris MN USA
| | - R. W Krohmer
- Department of Biological Sciences Saint Xavier University Chicago IL USA
| | - E. J. Uhrig
- Department of Integrative Biology Oregon State University Corvallis OR USA
| | - R. T. Mason
- Department of Integrative Biology Oregon State University Corvallis OR USA
| | - M. Olsson
- Department of Biological & Environmental Sciences University of Gothenburg Gothenburg Sweden
- School of Earth, Atmospheric and Life Sciences University of Wollongong Wollongong NSW Australia
| | - C. M. Whittington
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - C. R. Friesen
- School of Earth, Atmospheric and Life Sciences University of Wollongong Wollongong NSW Australia
- Illawarra Health and Medical Research Institute (IHMRI)University of Wollongong Wollongong NSW Australia
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6
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Kahrl AF, Johnson MA, Cox RM. Rapid evolution of testis size relative to sperm morphology suggests that post-copulatory selection targets sperm number in Anolis lizards. J Evol Biol 2019; 32:302-309. [PMID: 30659673 DOI: 10.1111/jeb.13414] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/14/2018] [Accepted: 01/14/2019] [Indexed: 11/28/2022]
Abstract
Post-copulatory sexual selection is thought to be responsible for much of the extraordinary diversity in sperm morphology across metazoans. However, the extent to which post-copulatory selection targets sperm morphology versus sperm production is generally unknown. To address this issue, we simultaneously characterized the evolution of sperm morphology (length of the sperm head, midpiece and flagellum) and testis size (a proxy for sperm production) across 26 species of Anolis lizards, a group in which sperm competition is likely. We found that the length of the sperm midpiece has evolved 2-3 times faster than that of the sperm head or flagellum, suggesting that midpiece size may be the most important aspect of sperm morphology with respect to post-copulatory sexual selection. However, testis size has evolved faster than any aspect of sperm morphology or body size, supporting the hypothesis that post-copulatory sexual selection acts more strongly upon sperm production than upon sperm morphology. Likewise, evolutionary increases in testis size, which typically indicate increased sperm competition, are not associated with predictable changes in sperm morphology, suggesting that any effects of post-copulatory selection on sperm morphology are either weak or variable in direction across anoles. Collectively, our results suggest that sperm production is the primary target of post-copulatory sexual selection in this lineage.
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Affiliation(s)
- Ariel F Kahrl
- Zoologiska institutionen: Etologi, Stockholm University, Stockholm, Sweden.,Department of Biology, University of Virginia, Charlottesville, Virginia
| | | | - Robert M Cox
- Department of Biology, University of Virginia, Charlottesville, Virginia
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7
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Laturney M, van Eijk R, Billeter JC. Last male sperm precedence is modulated by female remating rate in Drosophila melanogaster. Evol Lett 2018; 2:180-189. [PMID: 30283675 PMCID: PMC6121866 DOI: 10.1002/evl3.50] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 01/26/2018] [Accepted: 03/11/2018] [Indexed: 11/09/2022] Open
Abstract
Following multiple matings, sperm from different males compete for fertilization within the female reproductive tract. In many species, this competition results in an unequal sharing of paternity that favors the most recent mate, termed last male sperm precedence (LMSP). Much of our understanding of LMSP comes from studies in Drosophila melanogaster that focus on twice‐mated females with standardized latencies between successive matings. Despite accumulating evidence indicating that females often mate with more than two males and exhibit variation in the latency between matings, the consequences of mating rate on LMSP are poorly understood. Here, we developed a paradigm utilizing D. melanogaster in which females remated at various time intervals with either two or three transgenic males that produce fluorescent sperm (green, red, or blue). This genetic manipulation enables paternity assessment of offspring and male‐specific sperm fate examination in female reproductive tracts. We found that remating latency had no relationship with LMSP in females that mated with two males. However, LMSP was significantly reduced in thrice‐mated females with short remating intervals; coinciding with reduced last‐male sperm storage. Thus, female remating rate influences the relative share of paternity, the overall clutch paternity diversity, and ultimately the acquisition of indirect genetic benefits to potentially maximize female reproductive success.
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Affiliation(s)
- Meghan Laturney
- Groningen Institute for Evolutionary Life Sciences University of Groningen PO Box 11103 Groningen 9700 CC The Netherlands
| | - Roel van Eijk
- Groningen Institute for Evolutionary Life Sciences University of Groningen PO Box 11103 Groningen 9700 CC The Netherlands
| | - Jean-Christophe Billeter
- Groningen Institute for Evolutionary Life Sciences University of Groningen PO Box 11103 Groningen 9700 CC The Netherlands
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8
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Strine C, Brown A, Barnes C, Major T, Artchawakom T, Hill J, Suwanwaree P. Arboreal Mating Behaviors of the Big-Eyed Green Pit Viper (Trimeresurus macrops) in Northeast Thailand (Reptilia: Viperidae). CURRENT HERPETOLOGY 2018. [DOI: 10.5358/hsj.37.81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Colin Strine
- Suranaree University of Technology, Nakhon Ratchasima, THAILAND
- Sakaerat Environmental Research Station, Nakhon Ratchasima, THAILAND
| | - Andrew Brown
- University of Mississippi, Department of Biological Science, University, MS, USA
- Sakaerat Environmental Research Station, Nakhon Ratchasima, THAILAND
| | - Curt Barnes
- Suranaree University of Technology, Nakhon Ratchasima, THAILAND
- Sakaerat Environmental Research Station, Nakhon Ratchasima, THAILAND
| | - Tom Major
- School of Biological Sciences, Bangor University, WALES, UK
| | | | - Jacques Hill
- University of Arkansas, Department of Biological Science, Fayetteville, AR, USA
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9
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Rollings N, Uhrig EJ, Krohmer RW, Waye HL, Mason RT, Olsson M, Whittington CM, Friesen CR. Age-related sex differences in body condition and telomere dynamics of red-sided garter snakes. Proc Biol Sci 2018; 284:rspb.2016.2146. [PMID: 28381620 DOI: 10.1098/rspb.2016.2146] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 03/06/2017] [Indexed: 12/15/2022] Open
Abstract
Life-history strategies vary dramatically between the sexes, which may drive divergence in sex-specific senescence and mortality rates. Telomeres are tandem nucleotide repeats that protect the ends of chromosomes from erosion during cell division. Telomeres have been implicated in senescence and mortality because they tend to shorten with stress, growth and age. We investigated age-specific telomere length in female and male red-sided garter snakes, Thamnophis sirtalis parietalis We hypothesized that age-specific telomere length would differ between males and females given their divergent reproductive strategies. Male garter snakes emerge from hibernation with high levels of corticosterone, which facilitates energy mobilization to fuel mate-searching, courtship and mating behaviours during a two to four week aphagous breeding period at the den site. Conversely, females remain at the dens for only about 4 days and seem to invest more energy in growth and cellular maintenance, as they usually reproduce biennially. As male investment in reproduction involves a yearly bout of physiologically stressful activities, while females prioritize self-maintenance, we predicted male snakes would experience more age-specific telomere loss than females. We investigated this prediction using skeletochronology to determine the ages of individuals and qPCR to determine telomere length in a cross-sectional study. For both sexes, telomere length was positively related to body condition. Telomere length decreased with age in male garter snakes, but remained stable in female snakes. There was no correlation between telomere length and growth in either sex, suggesting that our results are a consequence of divergent selection on life histories of males and females. Different selection on the sexes may be the physiological consequence of the sexual dimorphism and mating system dynamics displayed by this species.
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Affiliation(s)
- Nicky Rollings
- School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), New South Wales 2006, Australia
| | - Emily J Uhrig
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.,Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Randolph W Krohmer
- Department of Biological Sciences, Saint Xavier University, Chicago, IL, USA
| | - Heather L Waye
- Division of Science and Mathematics, University of Minnesota, Morris, MN, USA
| | - Robert T Mason
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - Mats Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Camilla M Whittington
- School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), New South Wales 2006, Australia.,Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, Australia
| | - Christopher R Friesen
- School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), New South Wales 2006, Australia
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10
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Correlated evolution of sexually selected traits: interspecific variation in ejaculates, sperm morphology, copulatory mate guarding, and body size in two sympatric species of garter snakes. Behav Ecol Sociobiol 2017. [DOI: 10.1007/s00265-017-2414-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Using whole-group metabolic rate and behaviour to assess the energetics of courtship in red-sided garter snakes. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.06.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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12
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Villagrán-SantaCruz M, Mendoza-Cruz E, Granados-González G, Rheubert JL, Hernández-Gallegos O. Sperm storage in the viviparous lizard Sceloporus bicanthalis (Squamata: Phrynosomatidae), a species with continuous spermatogenesis. ZOOMORPHOLOGY 2016. [DOI: 10.1007/s00435-016-0327-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Friesen CR, Uhrig EJ, Mason RT, Brennan PLR. Female behaviour and the interaction of male and female genital traits mediate sperm transfer during mating. J Evol Biol 2016; 29:952-64. [PMID: 26809830 DOI: 10.1111/jeb.12836] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 02/04/2023]
Abstract
Natural selection and post-copulatory sexual selection, including sexual conflict, contribute to genital diversification. Fundamental first steps in understanding how these processes shape the evolution of specific genital traits are to determine their function experimentally and to understand the interactions between female and male genitalia during copulation. Our experimental manipulations of male and female genitalia in red-sided garter snakes (Thamnophis sirtalis parietalis) reveal that copulation duration and copulatory plug deposition, as well as total and oviductal/vaginal sperm counts, are influenced by the interaction between male and female genital traits and female behaviour during copulation. By mating females with anesthetized cloacae to males with spine-ablated hemipenes using a fully factorial design, we identified significant female-male copulatory trait interactions and found that females prevent sperm from entering their oviducts by contracting their vaginal pouch. Furthermore, these muscular contractions limit copulatory plug size, whereas the basal spine of the male hemipene aids in sperm and plug transfer. Our results are consistent with a role of sexual conflict in mating interactions and highlight the evolutionary importance of female resistance to reproductive outcomes.
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Affiliation(s)
- C R Friesen
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.,School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, USA
| | - E J Uhrig
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - R T Mason
- Department of Integrative Biology, Oregon State University, Corvallis, OR, USA
| | - P L R Brennan
- Department of Biological Sciences, 104 Clapp Laboratory, Mount Holyoke College, South Hadley, MA, USA
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14
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Friesen CR, Powers DR, Copenhaver PE, Mason RT. Size dependence in non-sperm ejaculate production is reflected in daily energy expenditure and resting metabolic rate. J Exp Biol 2015; 218:1410-8. [DOI: 10.1242/jeb.120402] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
ABSTRACT
The non-sperm components of an ejaculate, such as copulatory plugs, can be essential to male reproductive success. But the costs of these ejaculate components are often considered trivial. In polyandrous species, males are predicted to increase energy allocation to the production of non-sperm components, but this allocation is often condition dependent and the energetic costs of their production have never been quantified. Red-sided garter snakes (Thamnophis sirtalis parietalis) are an excellent model with which to quantify the energetic costs of non-sperm components of the ejaculate as they exhibit a dissociated reproductive pattern in which sperm production is temporally disjunct from copulatory plug production, mating and plug deposition. We estimated the daily energy expenditure and resting metabolic rate of males after courtship and mating, and used bomb calorimetry to estimate the energy content of copulatory plugs. We found that both daily energy expenditure and resting metabolic rate were significantly higher in small mating males than in courting males, and a single copulatory plug without sperm constitutes 5–18% of daily energy expenditure. To our knowledge, this is the first study to quantify the energetic expense of size-dependent ejaculate strategies in any species.
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Affiliation(s)
- Christopher R. Friesen
- School of Biological Sciences, University of Sydney, Heydon-Laurence Bldg AO8, Science Rd, Sydney, NSW 2006, Australia
- Department of Zoology, Oregon State University, Cordley Hall 3029, Corvallis, OR 97330, USA
| | - Donald R. Powers
- Department of Biology, George Fox University, Edwards-Holman Science Center, Newberg, OR 97132, USA
| | - Paige E. Copenhaver
- Department of Biology, George Fox University, Edwards-Holman Science Center, Newberg, OR 97132, USA
- Department of Botany and Program in Ecology, University of Wyoming, Aven Nelson Building 130, Laramie, WY 82071, USA
| | - Robert T. Mason
- Department of Zoology, Oregon State University, Cordley Hall 3029, Corvallis, OR 97330, USA
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15
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Friesen CR, Uhrig EJ, Mason RT. Females remate more frequently when mated with sperm-deficient males. ACTA ACUST UNITED AC 2014; 321:603-9. [PMID: 25366702 DOI: 10.1002/jez.1892] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/21/2014] [Accepted: 08/22/2014] [Indexed: 01/31/2023]
Abstract
Polyandry is a source of sexual conflict and males often try to limit female promiscuity. Consequently, male manipulation of receptivity via antiaphrodisiacs and copulatory plugs that prevent female remating can be a source of sexual conflict. This sexual conflict may be intensified when females must remate for fertility insurance. Male red-sided garter snakes produce a large, gelatinous copulatory plug that has been proposed to 1) physically prevent remating and 2) contain an antiaphrodisiac that reduces female receptivity. These males may become sperm depleted because of their dissociated reproductive pattern. If a female mates with a sperm deficient male and is also rendered unreceptive to further mating, then this represents a serious conflict. We tested whether female remating frequency is affected when females are mated with a male that produces a sperm-less copulatory plug. We show that females are significantly more likely to remate after mating with vasectomized males than intact males, even though vasectomized males still produce a copulatory plug. These results suggest that the ejaculate material of the plug does not contain an antiaphrodisiac. Instead, females may use sperm as a cue for post-copulatory mate assessment and seek to remate for the direct benefit of fertility insurance if they have mated with sperm-depleted males.
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Affiliation(s)
- Christopher R Friesen
- School of Biological Sciences, University of Sydney, Sydney, Australia; Department of Integrative Biology, Oregon State University, Corvallis, Oregon
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