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Chung MHJ, Mahmud-Al-Hasan M, Jennions MD, Head ML. Effects of inbreeding and elevated rearing temperatures on strategic sperm investment. Behav Ecol 2024; 35:arae044. [PMID: 38903732 PMCID: PMC11187721 DOI: 10.1093/beheco/arae044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 03/24/2024] [Accepted: 06/04/2024] [Indexed: 06/22/2024] Open
Abstract
Males often strategically adjust the number of available sperm based on the social context (i.e. sperm priming response), but it remains unclear how environmental and genetic factors shape this adjustment. In freshwater ecosystems, high ambient temperatures often lead to isolated pools of hotter water in which inbreeding occurs. Higher water temperatures and inbreeding can impair fish development, potentially disrupting sperm production. We used guppies (Poecilia reticulata) to investigate how developmental temperature (26 °C, 30 °C) and male inbreeding status (inbred, outbred) influence their sperm priming response. We also tested if sperm priming was affected by whether the female was a relative (sister) and whether she was inbred or outbred. There was no effect of rearing temperature; male inbreeding status alone determined the number of available sperm in response to female presence, her inbreeding status, and her relatedness. Inbred males produced significantly more sperm in the presence of an unrelated, outbred female than when no female was present. Conversely, outbred males did not alter the number of sperm available in response to female presence or relatedness. Moreover, inbred males produced marginally more sperm when exposed to an unrelated female that was outbred rather than inbred, but there was no difference when exposed to an inbred female that was unrelated versus related. Together, a sperm priming response was only observed in inbred males when exposed to an outbred female. Outbred females in our study were larger than inbred females, suggesting that inbred males strategically allocated ejaculate resources toward females in better condition.
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Affiliation(s)
- Meng-Han Joseph Chung
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Md Mahmud-Al-Hasan
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Michael D Jennions
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Centre, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Megan L Head
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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Atypical Centriolar Composition Correlates with Internal Fertilization in Fish. Cells 2022; 11:cells11050758. [PMID: 35269380 PMCID: PMC8909020 DOI: 10.3390/cells11050758] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/11/2022] [Accepted: 02/17/2022] [Indexed: 01/27/2023] Open
Abstract
The sperm competition theory, as proposed by Geoff Parker, predicts that sperm evolve through a cascade of changes. As an example, internal fertilization is followed by sperm morphology diversification. However, little is known about the evolution of internal sperm structures. The centriole has an ancient and evolutionarily conserved canonical structure with signature 9-fold, radially symmetric microtubules that form the cell’s centrosomes, cilia, and flagella. Most animal spermatozoa have two centrioles, one of which forms the spermatozoan flagellum. Both are delivered to the egg and constitute the embryo’s first two centrosomes. The spermatozoa of mammals and insects only have one recognizable centriole with a canonical structure. A second sperm centriole with an atypical structure was recently reported in both animal groups and which, prior to this, eluded discovery by standard techniques and criteria. Because the ancestors of both mammals and insects reproduced by internal fertilization, we hypothesized that the transition from two centrioles with canonical composition in ancestral sperm to an atypical centriolar composition characterized by only one canonical centriole evolved preferentially after internal fertilization. We examined fish because of the diversity of species available to test this hypothesis−as some species reproduce via internal and others via external fertilization−and because their spermatozoan ultrastructure has been extensively studied. Our literature search reports on 277 fish species. Species reported with atypical centriolar composition are specifically enriched among internal fertilizers compared to external fertilizers (7/34, 20.6% versus 2/243, 0.80%; p < 0.00001, odds ratio = 32.4) and represent phylogenetically unrelated fish. Atypical centrioles are present in the internal fertilizers of the subfamily Poeciliinae. Therefore, internally fertilizing fish preferentially and independently evolved spermatozoa with atypical centriolar composition multiple times, agreeing with Parker’s cascade theory.
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3
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Valvo JJ, Aponte JD, Daniel MJ, Dwinell K, Rodd H, Houle D, Hughes KA. Using Delaunay triangulation to sample whole-specimen color from digital images. Ecol Evol 2021; 11:12468-12484. [PMID: 34594513 PMCID: PMC8462138 DOI: 10.1002/ece3.7992] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/21/2021] [Indexed: 11/26/2022] Open
Abstract
Color variation is one of the most obvious examples of variation in nature, but biologically meaningful quantification and interpretation of variation in color and complex patterns are challenging. Many current methods for assessing variation in color patterns classify color patterns using categorical measures and provide aggregate measures that ignore spatial pattern, or both, losing potentially important aspects of color pattern.Here, we present Colormesh, a novel method for analyzing complex color patterns that offers unique capabilities. Our approach is based on unsupervised color quantification combined with geometric morphometrics to identify regions of putative spatial homology across samples, from histology sections to whole organisms. Colormesh quantifies color at individual sampling points across the whole sample.We demonstrate the utility of Colormesh using digital images of Trinidadian guppies (Poecilia reticulata), for which the evolution of color has been frequently studied. Guppies have repeatedly evolved in response to ecological differences between up- and downstream locations in Trinidadian rivers, resulting in extensive parallel evolution of many phenotypes. Previous studies have, for example, compared the area and quantity of discrete color (e.g., area of orange, number of black spots) between these up- and downstream locations neglecting spatial placement of these areas. Using the Colormesh pipeline, we show that patterns of whole-animal color variation do not match expectations suggested by previous work.Colormesh can be deployed to address a much wider range of questions about color pattern variation than previous approaches. Colormesh is thus especially suited for analyses that seek to identify the biologically important aspects of color pattern when there are multiple competing hypotheses or even no a priori hypotheses at all.
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Affiliation(s)
- Jennifer J. Valvo
- Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Jose David Aponte
- Department of Cell Biology and AnatomyUniversity of CalgaryCalgaryABCanada
| | - Mitch J. Daniel
- Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Kenna Dwinell
- Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Helen Rodd
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - David Houle
- Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
| | - Kimberly A. Hughes
- Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
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4
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Meta-analytic evidence that animals rarely avoid inbreeding. Nat Ecol Evol 2021; 5:949-964. [PMID: 33941905 DOI: 10.1038/s41559-021-01453-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 03/24/2021] [Indexed: 02/02/2023]
Abstract
Animals are usually expected to avoid mating with relatives (kin avoidance) as incestuous mating can lead to the expression of inbreeding depression. Yet, theoretical models predict that unbiased mating with regards to kinship should be common, and that under some conditions, the inclusive fitness benefits associated with inbreeding can even lead to a preference for mating with kin. This mismatch between empirical and theoretical expectations generates uncertainty as to the prevalence of inbreeding avoidance in animals. Here, we synthesized 677 effect sizes from 139 experimental studies of mate choice for kin versus non-kin in diploid animals, representing 40 years of research, using a meta-analytical approach. Our meta-analysis revealed little support for the widely held view that animals avoid mating with kin, despite clear evidence of publication bias. Instead, unbiased mating with regards to kinship appears widespread across animals and experimental conditions. The significance of a variety of moderators was explored using meta-regressions, revealing that the degree of relatedness and prior experience with kin explained some variation in the effect sizes. Yet, we found no difference in kin avoidance between males and females, choice and no-choice experiments, mated and virgin animals or between humans and animals. Our findings highlight the need to rethink the widely held view that inbreeding avoidance is a given in experimental studies.
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Vuarin P, Bouchard A, Lesobre L, Levêque G, Chalah T, Saint Jalme M, Lacroix F, Hingrat Y, Sorci G. No evidence for prezygotic postcopulatory avoidance of kin despite high inbreeding depression. Mol Ecol 2018; 27:5252-5262. [PMID: 30565783 DOI: 10.1111/mec.14951] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 10/17/2018] [Indexed: 12/17/2022]
Abstract
Offspring resulting from mating among close relatives can suffer from impaired fitness through the expression of recessive alleles with deleterious effects. Postcopulatory sperm selection (a prezygotic mechanism of cryptic female choice) has been suggested to be an effective way to avoid inbreeding. To investigate whether postcopulatory female choice allows the avoidance of fertilization by close kin, we performed artificial inseminations in a promiscuous bird, the houbara bustard (Chlamydotis undulata undulata). Females were inseminated with a mix of sperm from triads of males, each constituted of a male genetically unrelated to the female, a first cousin and a half-sibling. When counting the number of eggs sired by unrelated males, cousins or half-siblings, we found a significant deviation from the expected random distribution, with more eggs sired by unrelated males. However, offspring sired by cousins, and especially by half-siblings suffered from high prehatching mortality, suggesting that the observed paternity skew towards unrelated males might reflect differential offspring mortality rather than sperm selection. In agreement with this hypothesis, within-triad siring success was similar for the three parental relatedness categories, but the relationship between siring and hatching success differed across categories. In clutches with high hatching success, unrelated males had the highest success while in clutches with high failure rate, half-siblings had the highest success. Offspring sired by half-siblings also suffered from reduced growth rate during the first three months and higher posthatching mortality. Hence, despite substantial fitness costs associated with fertilization by close relatives, females do not seem to select sperm of unrelated males.
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Affiliation(s)
- Pauline Vuarin
- Emirates left for Wildlife Propagation, Missour, Morocco.,Biogéosciences, UMR 6282 CNRS, Université de Bourgogne Franche-Comté, Dijon, France
| | - Alice Bouchard
- Emirates left for Wildlife Propagation, Missour, Morocco
| | - Loïc Lesobre
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
| | | | - Toni Chalah
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
| | - Michel Saint Jalme
- Centre d'Ecologie et des Sciences de la Conservation, UMR 7204 MNHN CNRS-UPMC, Museum National d'Histoire Naturelle, Paris, France
| | - Frédéric Lacroix
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
| | - Yves Hingrat
- Reneco International Wildlife Consultants LLC, Abu Dhabi, United Arab Emirates
| | - Gabriele Sorci
- Biogéosciences, UMR 6282 CNRS, Université de Bourgogne Franche-Comté, Dijon, France
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6
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Fitzpatrick JL, Evans JP. Postcopulatory inbreeding avoidance in guppies. J Evol Biol 2014; 27:2585-94. [PMID: 25387854 DOI: 10.1111/jeb.12545] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/22/2014] [Accepted: 10/23/2014] [Indexed: 01/18/2023]
Abstract
In many species, the negative fitness effects of inbreeding have facilitated the evolution of a wide range of inbreeding avoidance mechanisms. Although avoidance mechanisms operating prior to mating are well documented, evidence for postcopulatory mechanisms of inbreeding avoidance remain scarce. Here, we examine the potential for paternity biases to favour unrelated males when their sperm compete for fertilizations though postcopulatory inbreeding avoidance mechanisms in the guppy, Poecilia reticulata. To test this possibility, we used a series of artificial inseminations to deliver an equal number of sperm from a related (either full sibling or half sibling) and unrelated male to a female while statistically controlling for differences in sperm quality between rival ejaculates. In this way, we were able to focus exclusively on postcopulatory mechanisms of inbreeding avoidance and account for differences in sperm competitiveness between rival males. Under these carefully controlled conditions, we report a significant bias in paternity towards unrelated males, although this effect was only apparent when the related male was a full sibling. We also show that sperm competition generally favours males with highly viable sperm and thus that some variance in sperm competitiveness can be attributed to difference in sperm quality. Our findings for postcopulatory inbreeding avoidance are consistent with prior work on guppies, revealing that sperm competition success declines linearly with the level of relatedness, but also that such effects are only apparent at relatedness levels of full siblings or higher. These findings reveal that postcopulatory processes alone can facilitate inbreeding avoidance.
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Affiliation(s)
- J L Fitzpatrick
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester, UK; Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, WA, Australia
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7
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Collet JM, Blows MW. Female mate choice predicts paternity success in the absence of additive genetic variance for other female paternity bias mechanisms in Drosophila serrata. J Evol Biol 2014; 27:2568-72. [PMID: 25290296 DOI: 10.1111/jeb.12511] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 08/28/2014] [Accepted: 09/08/2014] [Indexed: 11/29/2022]
Abstract
After choosing a first mate, polyandrous females have access to a range of opportunities to bias paternity, such as repeating matings with the preferred male, facilitating fertilization from the best sperm or differentially investing in offspring according to their sire. Female ability to bias paternity after a first mating has been demonstrated in a few species, but unambiguous evidence remains limited by the access to complex behaviours, sperm storage organs and fertilization processes within females. Even when found at the phenotypic level, the potential evolution of any mechanism allowing females to bias paternity other than mate choice remains little explored. Using a large population of pedigreed females, we developed a simple test to determine whether there is additive genetic variation in female ability to bias paternity after a first, chosen, mating. We applied this method in the highly polyandrous Drosophila serrata, giving females the opportunity to successively mate with two males ad libitum. We found that despite high levels of polyandry (females mated more than once per day), the first mate choice was a significant predictor of male total reproductive success. Importantly, there was no detectable genetic variance in female ability to bias paternity beyond mate choice. Therefore, whether or not females can bias paternity before or after copulation, their role on the evolution of sexual male traits is likely to be limited to their first mate choice in D. serrata.
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Affiliation(s)
- J M Collet
- School of Biological Sciences, University of Queensland, St Lucia, Qld, Australia
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8
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Slatyer RA, Mautz BS, Backwell PRY, Jennions MD. Estimating genetic benefits of polyandry from experimental studies: a meta-analysis. Biol Rev Camb Philos Soc 2011; 87:1-33. [PMID: 21545390 DOI: 10.1111/j.1469-185x.2011.00182.x] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rachel A Slatyer
- Evolution, Ecology & Genetics, Research School of Biology, The Australian National University, Canberra, Australia
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9
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Ala-Honkola O, Manier MK, Lüpold S, Pitnick S. No evidence for postcopulatory inbreeding avoidance in Drosophila melanogaster. Evolution 2011; 65:2699-705. [PMID: 21884066 DOI: 10.1111/j.1558-5646.2011.01317.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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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10
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Gasparini C, Pilastro A. Cryptic female preference for genetically unrelated males is mediated by ovarian fluid in the guppy. Proc Biol Sci 2011; 278:2495-501. [PMID: 21227973 DOI: 10.1098/rspb.2010.2369] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As inbreeding is costly, it has been suggested that polyandry may evolve as a means to reduce the negative fitness consequences of mating with genetically related males. While several studies provide support for this hypothesis, evidence of pure post-copulatory mechanisms capable of biasing paternity towards genetically unrelated males is still lacking; yet these are necessary to support inbreeding avoidance models of polyandry evolution. Here we showed, by artificially inseminating a group of female guppies with an equal number of sperm from related (full-sib) and unrelated males, that sperm competition success of the former was 10 per cent lower, on average, than that of the unrelated male. The paternity bias towards unrelated males was not due to differential embryo survival, as the size of the brood produced by control females, which were artificially inseminated with the sperm of a single male, was not influenced by their relatedness with the male. Finally, we collected ovarian fluid (OF) from virgin females. Using computer-assisted sperm analysis, we found that sperm velocity, a predictor of sperm competition success in the guppy, was significantly lower when measured in a solution containing the OF from a sister as compared with that from an unrelated female. Our results suggest that sperm-OF interaction mediates sperm competition bias towards unrelated mates and highlight the role of post-copulatory mechanisms in reducing the cost of mating with relatives in polyandrous females.
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11
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Johnson AM, Chappell G, Price AC, Helen Rodd F, Olendorf R, Hughes KA. Inbreeding Depression and Inbreeding Avoidance in a Natural Population of Guppies (Poecilia reticulata). Ethology 2010. [DOI: 10.1111/j.1439-0310.2010.01763.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Ala-Honkola O, Tuominen L, Lindström K. Inbreeding avoidance in a poeciliid fish (Heterandria formosa). Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-0955-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Hettyey A, Hegyi G, Puurtinen M, Hoi H, Török JÃ, Penn DJ. Mate Choice for Genetic Benefits: Time to Put the Pieces Together. Ethology 2010. [DOI: 10.1111/j.1439-0310.2009.01704.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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14
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Gasparini C, Marino IAM, Boschetto C, Pilastro A. Effect of male age on sperm traits and sperm competition success in the guppy (Poecilia reticulata). J Evol Biol 2009; 23:124-35. [PMID: 19912453 DOI: 10.1111/j.1420-9101.2009.01889.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Deleterious mutations can accumulate in the germline with age, decreasing the genetic quality of sperm and imposing a cost on female fitness. If these mutations also affect sperm competition ability or sperm production, then females will benefit from polyandry as it incites sperm competition and, consequently, minimizes the mutational load in the offspring. We tested this hypothesis in the guppy (Poecilia reticulata), a species characterized by polyandry and intense sperm competition, by investigating whether age affects post-copulatory male traits and sperm competition success. Females did not discriminate between old and young males in a mate choice experiment. While old males produced longer and slower sperm with larger reserves of strippable sperm, compared to young males, artificial insemination did not reveal any effect of age on sperm competition success. Altogether, these results do not support the hypothesis that polyandry evolved in response to costs associated with mating with old males in the guppy.
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Affiliation(s)
- C Gasparini
- Dipartimento di Biologia, Università di Padova, Padova, Italy.
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15
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BRETMAN AMANDA, NEWCOMBE DEVI, TREGENZA TOM. Promiscuous females avoid inbreeding by controlling sperm storage. Mol Ecol 2009; 18:3340-5. [DOI: 10.1111/j.1365-294x.2009.04301.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Zajitschek SRK, Lindholm AK, Evans JP, Brooks RC. Experimental evidence that high levels of inbreeding depress sperm competitiveness. J Evol Biol 2009; 22:1338-45. [PMID: 19344380 DOI: 10.1111/j.1420-9101.2009.01738.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effects of inbreeding on sperm quantity and quality are among the most dramatic examples of inbreeding depression. The extent to which inbreeding depression results in decreased fertilization success of a male's sperm, however, remains largely unknown. This task is made more difficult by the fact that other factors, such as cryptic female choice, male sperm allocation and mating order, can also drive patterns of paternity. Here, we use artificial insemination to eliminate these extraneous sources of variation and to measure the effects of inbreeding on the competitiveness of a male's sperm. We simultaneously inseminated female guppies (Poecilia reticulata) with equal amounts of sperm from an outbred (f = 0) male and either a highly (f = 0.59) or a moderately inbred (f = 0.25) male. Highly inbred males sired significantly fewer offspring than outbred males, but share of paternity did not differ between moderately inbred and outbred males. These findings therefore confirm that severe inbreeding can impair the competitiveness of sperm, but suggest that in the focal population inbreeding at order of a brother-sister mating does not reduce a male's sperm competitiveness.
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Affiliation(s)
- S R K Zajitschek
- Evolution and Ecology Research Centre, School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW, Australia.
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