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Pike VL, Cornwallis CK, Griffin AS. Why don't all animals avoid inbreeding? Proc Biol Sci 2021; 288:20211045. [PMID: 34344184 PMCID: PMC8334842 DOI: 10.1098/rspb.2021.1045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/12/2021] [Indexed: 01/22/2023] Open
Abstract
Individuals are expected to avoid mating with relatives as inbreeding can reduce offspring fitness, a phenomenon known as inbreeding depression. This has led to the widespread assumption that selection will favour individuals that avoid mating with relatives. However, the strength of inbreeding avoidance is variable across species and there are numerous cases where related mates are not avoided. Here we test if the frequency that related males and females encounter each other explains variation in inbreeding avoidance using phylogenetic meta-analysis of 41 different species from six classes across the animal kingdom. In species reported to mate randomly with respect to relatedness, individuals were either unlikely to encounter relatives, or inbreeding had negligible effects on offspring fitness. Mechanisms for avoiding inbreeding, including active mate choice, post-copulatory processes and sex-biased dispersal, were only found in species with inbreeding depression. These results help explain why some species seem to care more about inbreeding than others: inbreeding avoidance through mate choice only evolves when there is both a risk of inbreeding depression and related sexual partners frequently encounter each other.
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Wei X, Zhang J. The optimal mating distance resulting from heterosis and genetic incompatibility. SCIENCE ADVANCES 2018; 4:eaau5518. [PMID: 30417098 PMCID: PMC6221538 DOI: 10.1126/sciadv.aau5518] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/10/2018] [Indexed: 05/30/2023]
Abstract
Theory predicts that the fitness of an individual is maximized when the genetic distance between its parents (i.e., mating distance) is neither too small nor too large. However, decades of research have generally failed to validate this prediction or identify the optimal mating distance (OMD). Respectively analyzing large numbers of crosses of fungal, plant, and animal model organisms, we indeed find the hybrid phenotypic value a humped quadratic polynomial function of the mating distance for the vast majority of fitness-related traits examined, with different traits of the same species exhibiting similar OMDs. OMDs are generally slightly greater than the nucleotide diversities of the species concerned but smaller than the observed maximal intraspecific genetic distances. Hence, the benefit of heterosis is at least partially offset by the harm of genetic incompatibility even within species. These results have multiple theoretical and practical implications for speciation, conservation, and agriculture.
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Dugand RJ, Kennington WJ, Tomkins JL. Evolutionary divergence in competitive mating success through female mating bias for good genes. SCIENCE ADVANCES 2018; 4:eaaq0369. [PMID: 29806021 PMCID: PMC5966190 DOI: 10.1126/sciadv.aaq0369] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Accepted: 04/11/2018] [Indexed: 06/08/2023]
Abstract
Despite heritable variation for univariate sexually selected traits, recent analyses exploring multivariate traits find evidence consistent with the lek paradox in showing no genetic variation available to choosy females, and therefore no genetic benefits of choice. We used the preferences of Drosophila melanogaster females to exert bidirectional selection on competitive male mating success to test for the presence and nature of genetic variation underlying this multivariate trait. Male mating success diverged between selection regimens, and flies from success-selected lines had a smaller burden of deleterious, recessive mutations that affect egg-to-adult viability, were better sperm competitors (sperm offence), and did not demonstrate reduced desiccation resistance or components of female fitness (traits thought to trade off with attractiveness) relative to flies from failure-selected populations. Mating success remained subject to inbreeding depression in success-selected lines, suggesting that variation in mating success remains, thanks to numerous genes of small effect. Together, our results provide unique evidence for the evolutionary divergence in male mating success, demonstrating that genetic variation is not exhausted along the axis of precopulatory sexual selection and that female mating biases align with the avoidance of bad genes.
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Lawrence M, Mastromonaco G, Goodrowe K, Santymire R, Waddell W, Schulte-Hostedde A. The effects of inbreeding on sperm morphometry of captive-bred endangered mammals. CAN J ZOOL 2017. [DOI: 10.1139/cjz-2016-0291] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Captive breeding is used for the conservation of endangered species, but inbreeding can result when a small number of founders are used to establish populations. Inbreeding can reduce the proportion of normal sperm in an ejaculate, but may also have effects on sperm size and shape (morphometry). We investigated the effects of inbreeding on sperm morphometry of black-footed ferrets (Mustela nigripes (Audubon and Bachman, 1851)) and red wolves (Canis rufus Audubon and Bachman, 1851) from captive breeding programs to determine if more inbred males produced sperm of poor quality (bulky head, small midpiece, short tail). We measured sperm head length, head width, midpiece length, midpiece width, and tail length on 10 sperm from each male of both species. A negative relationship between variation in sperm tail length and inbreeding coefficient (f) was found in black-footed ferret, suggesting that more inbred individuals will have reduced genetic and phenotypic variation. Analyses indicated a negative relationship between sperm head width and f and a positive relationship between sperm tail length and f in red wolf, suggesting that more inbred male red wolves could have faster sperm. These results indicate that inbreeding affects functionally important aspects of sperm morphometry, but that these effects may not be entirely negative.
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Affiliation(s)
- M. Lawrence
- Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada
| | - G. Mastromonaco
- Reproductive Physiology, Toronto Zoo, Scarborough, ON M1B 5K7, Canada
| | - K. Goodrowe
- Point Defiance Zoo and Aquarium, Tacoma, WA 98407, USA
| | - R.M. Santymire
- Davee Center for Epidemiology and Endocrinology, Lincoln Park Zoo, Chicago, IL 60614, USA
| | - W. Waddell
- Point Defiance Zoo and Aquarium, Tacoma, WA 98407, USA
| | - A.I. Schulte-Hostedde
- Department of Biology, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada
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Langen K, Bakker TCM, Baldauf SA, Shrestha J, Thünken T. Effects of ageing and inbreeding on the reproductive traits in a cichlid fish II: the female perspective. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blw003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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6
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Langen K, Bakker TCM, Baldauf SA, Shrestha J, Thünken T. Effects of ageing and inbreeding on the reproductive traits in a cichlid fish I: the male perspective. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blw002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Ebel ER, Phillips PC. Intrinsic differences between males and females determine sex-specific consequences of inbreeding. BMC Evol Biol 2016; 16:36. [PMID: 26860745 PMCID: PMC4748534 DOI: 10.1186/s12862-016-0604-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/28/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Inbreeding increases homozygosity and exposes deleterious recessive alleles, generally decreasing the fitness of inbred individuals. Interestingly, males and females are usually affected differently by inbreeding, though the more vulnerable sex depends on the species and trait measured. RESULTS We used the soil-dwelling nematode Caenorhabditis remanei to examine sex-specific inbreeding depression across nine lineages, five levels of inbreeding, and hundreds of thousands of progeny. Female nematodes consistently suffered greater fitness losses than their male counterparts, especially at high levels of inbreeding. CONCLUSIONS These results suggest that females experience stronger selection on genes contributing to reproductive traits. Inbreeding depression in males may be further reduced by sex chromosome hemizygosity, which affects the dominance of some mutations, as well as by the absence of sexual selection. Determining the relative contributions of sex-specific expression, genes on the sex chromosomes, and the environment they are filtered through-including opportunities for sexual selection-may explain the frequent though inconsistent records of sex differences in inbreeding depression, along with their implications for conservation and the evolution of mating systems.
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Affiliation(s)
- Emily R Ebel
- Institute of Ecology and Evolution and Department of Biology, 5289 University of Oregon, 97403, Eugene, Oregon, USA.,Present address: Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution and Department of Biology, 5289 University of Oregon, 97403, Eugene, Oregon, USA.
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8
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Dolphin K, Carter A. Inbreeding decreases promiscuity in Drosophila melanogasterfemales. ETHOL ECOL EVOL 2015. [DOI: 10.1080/03949370.2015.1039466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Ala-Honkola O, Veltsos P, Anderson H, Ritchie MG. Copulation duration, but not paternity share, potentially mediates inbreeding avoidance in Drosophila montana. Behav Ecol Sociobiol 2014. [DOI: 10.1007/s00265-014-1807-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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10
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Stelkens RB, Brockhurst MA, Hurst GDD, Greig D. Hybridization facilitates evolutionary rescue. Evol Appl 2014; 7:1209-17. [PMID: 25558281 PMCID: PMC4275092 DOI: 10.1111/eva.12214] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 08/05/2014] [Indexed: 12/23/2022] Open
Abstract
The resilience of populations to rapid environmental degradation is a major concern for biodiversity conservation. When environments deteriorate to lethal levels, species must evolve to adapt to the new conditions to avoid extinction. Here, we test the hypothesis that evolutionary rescue may be enabled by hybridization, because hybridization increases genetic variability. Using experimental evolution, we show that interspecific hybrid populations of Saccharomyces yeast adapt to grow in more highly degraded environments than intraspecific and parental crosses, resulting in survival rates far exceeding those of their ancestors. We conclude that hybridization can increase evolutionary responsiveness and that taxa able to exchange genes with distant relatives may better survive rapid environmental change.
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Affiliation(s)
- Rike B Stelkens
- Institute of Integrative Biology, University of Liverpool Liverpool, UK
| | | | - Gregory D D Hurst
- Institute of Integrative Biology, University of Liverpool Liverpool, UK
| | - Duncan Greig
- Max Planck Institute for Evolutionary Biology Plön, Germany ; The Galton Laboratory, Department of Genetics, Evolution, and Environment, University College London London, UK
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11
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Losdat S, Chang SM, Reid JM. Inbreeding depression in male gametic performance. J Evol Biol 2014; 27:992-1011. [DOI: 10.1111/jeb.12403] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 12/23/2022]
Affiliation(s)
- S. Losdat
- Institute of Biological and Environmental Sciences; School of Biological Sciences; University of Aberdeen; Aberdeen UK
| | - S.-M. Chang
- Plant Biology Department; University of Georgia; Athens GA USA
| | - J. M. Reid
- Institute of Biological and Environmental Sciences; School of Biological Sciences; University of Aberdeen; Aberdeen UK
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12
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Stelkens RB, Pompini M, Wedekind C. Testing the effects of genetic crossing distance on embryo survival within a metapopulation of brown trout (Salmo trutta). CONSERV GENET 2014. [DOI: 10.1007/s10592-013-0545-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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13
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Robinson SP, Simmons LW, Kennington WJ. Estimating relatedness and inbreeding using molecular markers and pedigrees: the effect of demographic history. Mol Ecol 2013; 22:5779-92. [PMID: 24102888 DOI: 10.1111/mec.12529] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 09/06/2013] [Accepted: 09/09/2013] [Indexed: 11/30/2022]
Abstract
Estimates of inbreeding and relatedness are commonly calculated using molecular markers, although the accuracy of such estimates has been questioned. As a further complication, in many situations, such estimates are required in populations with reduced genetic diversity, which is likely to affect their accuracy. We investigated the correlation between microsatellite- and pedigree-based coefficients of inbreeding and relatedness in laboratory populations of Drosophila melanogaster that had passed through bottlenecks to manipulate their genetic diversity. We also used simulations to predict expected correlations between marker- and pedigree-based estimates and to investigate the influence of linkage between loci and null alleles. Our empirical data showed lower correlations between marker- and pedigree-based estimates in our control (nonbottleneck) population than were predicted by our simulations or those found in similar studies. Correlations were weaker in bottleneck populations, confirming that extreme reductions in diversity can compromise the ability of molecular estimates to detect recent inbreeding events. However, this result was highly dependent on the strength of the bottleneck and we did not observe or predict any reduction in correlations in our population that went through a relatively severe bottleneck of N = 10 for one generation. Our results are therefore encouraging, as molecular estimates appeared robust to quite severe reductions in genetic diversity. It should also be remembered that pedigree-based estimates may not capture realized identity-by-decent and that marker-based estimates may actually be more useful in certain situations.
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Affiliation(s)
- S P Robinson
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, WA, 6009, Australia
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Lizé A, McKay R, Lewis Z. Kin recognition in Drosophila: the importance of ecology and gut microbiota. ISME JOURNAL 2013; 8:469-77. [PMID: 24030598 DOI: 10.1038/ismej.2013.157] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 05/27/2013] [Accepted: 08/06/2013] [Indexed: 11/09/2022]
Abstract
The animal gut commonly contains a large reservoir of symbiotic microbes. Although these microbes have obvious functions in digestion and immune defence, gut microbes can also affect behaviour. Here, we explore whether gut microbiota has a role in kin recognition. We assessed whether relatedness, familiarity and food eaten during development altered copulation investment in three species of Drosophila with diverse ecologies. We found that a monandrous species exhibited true kin recognition, whereas familiarity determined kin recognition in a species living in dense aggregations. Finally, in a food generalist species, food eaten during development masked kin recognition. The effect of food type on copulation duration, in addition to the removal of this effect via antibiotic treatment, suggests the influence of bacteria associated with the gut. Our results provide the first evidence that varied ecologically determined mechanisms of kin recognition occur in Drosophila, and that gut bacteria are likely to have a key role in these mechanisms.
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Affiliation(s)
- Anne Lizé
- Department Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Raegan McKay
- Department Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Zenobia Lewis
- Department Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
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15
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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] [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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Loyau A, Cornuau JH, Clobert J, Danchin E. Incestuous sisters: mate preference for brothers over unrelated males in Drosophila melanogaster. PLoS One 2012; 7:e51293. [PMID: 23251487 PMCID: PMC3519633 DOI: 10.1371/journal.pone.0051293] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 11/01/2012] [Indexed: 11/20/2022] Open
Abstract
The literature is full of examples of inbreeding avoidance, while recent mathematical models predict that inbreeding tolerance or even inbreeding preference should be expected under several realistic conditions like e.g. polygyny. We investigated male and female mate preferences with respect to relatedness in the fruit fly D. melanogaster. Experiments offered the choice between a first order relative (full-sibling or parent) and an unrelated individual with the same age and mating history. We found that females significantly preferred mating with their brothers, thus supporting inbreeding preference. Moreover, females did not avoid mating with their fathers, and males did not avoid mating with their sisters, thus supporting inbreeding tolerance. Our experiments therefore add empirical evidence for inbreeding preference, which strengthens the prediction that inbreeding tolerance and preference can evolve under specific circumstances through the positive effects on inclusive fitness.
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Affiliation(s)
- Adeline Loyau
- CNRS, Station d'Ecologie Expérimentale du CNRS à Moulis, USR 2936, Saint Girons, France.
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17
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18
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Robinson SP, Kennington WJ, Simmons LW. Assortative mating for relatedness in a large naturally occurring population of Drosophila melanogaster. J Evol Biol 2012; 25:716-25. [PMID: 22321157 DOI: 10.1111/j.1420-9101.2012.02466.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stephen P Robinson
- Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA, Australia.
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Thoss M, Ilmonen P, Musolf K, Penn DJ. Major histocompatibility complex heterozygosity enhances reproductive success. Mol Ecol 2011; 20:1546-57. [PMID: 21291500 DOI: 10.1111/j.1365-294x.2011.05009.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We investigated how heterozygosity at the major histocompatibility complex (MHC) affects fitness in wild-derived (F2) house mice (Mus musculus musculus). To compare and control for potential confounding effects from close inbreeding and genome-wide heterozygosity, we used mice that were systematically outbred. We assessed how heterozygosity at MHC and background loci (using 15 microsatellite markers on 11 different chromosomes) affects individual survival and reproductive success (RS) in large, semi-natural population enclosures. We found that overall heterozygosity significantly increased RS, and this correlation was entirely explained by heterozygosity at two MHC loci. Moreover, we found that the effects of MHC heterozygosity depend on the level of background heterozygosity, and the benefits of maximal MHC heterozygosity show a curvilinear effect with increasing background heterozygosity. The enhanced RS from MHC heterozygosity was not because of increased survival, and although MHC heterozygosity was correlated with body mass, body mass did not correlate with RS when heterozygosity is controlled. Breeders were more MHC heterozygous than nonbreeders for both sexes, indicating that MHC heterozygosity enhanced fecundity, mating success or both. Our results show that (i) MHC heterozygosity enhances fitness among wild, outbred as well as congenic laboratory mice; (ii) heterozygosity-fitness correlations can potentially be explained by a few loci, such as MHC; (iii) MHC heterozygosity can increase fitness, even without affecting survival, by increasing mating and RS; and (iv) MHC effects depend on background genes, and maximal MHC heterozygosity is most beneficial at intermediate or optimal levels of background heterozygosity.
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Affiliation(s)
- M Thoss
- Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Savoyenstrasse 1a, Vienna, Austria
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Affiliation(s)
- L W Simmons
- Centre for Evolutionary Biology, School of Animal Biology (M092), University of Western Australia, Crawley, Australia.
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Enders LS, Nunney L. Sex-specific effects of inbreeding in wild-caught Drosophila melanogaster under benign and stressful conditions. J Evol Biol 2010; 23:2309-23. [PMID: 20874846 DOI: 10.1111/j.1420-9101.2010.02085.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In animal populations, sib mating is often the primary source of inbreeding depression (ID). We used recently wild-caught Drosophila melanogaster to test whether such ID is amplified by environmental stress and, in males, by sexual selection. We also investigated whether increased ID because of stress (increased larval competition) persisted beyond the stressed stage and whether the effects of stress and sexual selection interacted. Sib mating resulted in substantial cumulative fitness losses (egg to adult reproduction) of 50% (benign) and 73% (stressed). Stress increased ID during the larval period (23% vs. 63%), but not during post-stress reproductive stages (36% vs. 31%), indicating larval stress may have purged some adult genetic load (although ID was uncorrelated across stages). Sexual selection exacerbated inbreeding depression, with inbred male offspring suffering a higher reproductive cost than females, independent of stress (57% vs. 14% benign, 49% vs. 11% stress).
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Affiliation(s)
- L S Enders
- Department of Ecology, Evolution and Organismal Biology, University of California, Riverside, CA 92507, USA.
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