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Madsen T, Ujvari B, Bauwens D, Gruber B, Georges A, Klaassen M. Polyandry and non-random fertilisation maintain long-term genetic diversity in an isolated island population of adders (Vipera berus). Heredity (Edinb) 2023; 130:64-72. [PMID: 36474024 PMCID: PMC9905584 DOI: 10.1038/s41437-022-00578-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 11/09/2022] [Accepted: 11/12/2022] [Indexed: 12/12/2022] Open
Abstract
Conservation genetic theory suggests that small and isolated populations should be subject to reduced genetic diversity i.e., heterozygosity and allelic diversity. Our 34 years study of an isolated island population of adders (Vipera berus) in southern Sweden challenges this notion. Despite a lack of gene flow and a yearly mean estimated reproductive adult population size of only 65 adult adders (range 12-171), the population maintains high levels of heterozygosity and allelic diversity similar to that observed in two mainland populations. Even a 14-year major "bottleneck" i.e., a reduction in adult adder numbers, encompassing at least four adder generations, did not result in any reduction in the island adders' heterozygosity and allelic diversity. Female adders are polyandrous, and fertilisation is non-random, which our empirical data and modelling suggest are underpinning the maintenance of the population's high level of heterozygosity. Our empirical results and subsequent modelling suggest that the positive genetic effects of polyandry in combination with non-random fertilisation, often overlooked in conservation genetic analyses, deserve greater consideration when predicting long-term survival of small and isolated populations.
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Affiliation(s)
- Thomas Madsen
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, 3217, Australia.
| | - Beata Ujvari
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, 3217, Australia
| | - Dirk Bauwens
- Department of Biology, Laboratory of Functional Morphology, University of Antwerp, Wilrijk, Belgium
| | - Bernd Gruber
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia
| | - Marcel Klaassen
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, 3217, Australia
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2
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Do female amphibians and reptiles have greater reproductive output if they have more mates? Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03194-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Abstract
In general, males mate with multiple females to increase individual reproductive success. Whether or not, and under what circumstances, females benefit from multiple mating has been less clear. Our review of 154 studies covering 184 populations of amphibians and reptiles showed that polyandry was widespread and variable among and within taxonomic groups. We investigated whether amphibian and reptile females had greater reproductive output as the number of sires for offspring increased. Meta-analysis revealed significant heterogeneity in the dataset of all taxa. Expected heterozygosity was a significant moderator (covariate) of positive relationships between female reproductive output and the number of sires, but a sensitivity test showed the result was tenuous. Significant heterogeneity remained despite controlling for expected heterozygosity and other variables but was resolved for most taxonomic groups with subgroup meta-analyses. Subgroup meta-analyses showed that only female salamanders (Caudata) had significantly greater reproductive output with an increased number of sires. For many species of Caudata, males cannot coerce females into accepting spermatophores. We therefore suggest that if females control the number of matings, they can use polyandry to increase their fitness. Caudata offers ideal models with which to test this hypothesis and to explore factors enabling and maintaining the evolution of female choice. Outstanding problems may be addressed by expanding taxonomic coverage and data collection and improving data reporting.
Significance Statement
Many factors and combinations of factors drive polyandry. Whether or not females benefit from mating with more than one male remains equivocal. Focusing on amphibians and reptiles, our analyses demonstrate that female salamanders produced more offspring when mated with multiple males, whereas this was not the case for reptiles. Unlike many other species in our dataset, the polyandrous female salamanders fully control sperm intake and have chosen to mate multiple times. We further highlight problems and key directions for future research in the field.
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Jennings SL, Hoover BA, Wa Sin SY, Ebeler SE. Feather chemicals contain information about the major histocompatibility complex in a highly scented seabird. Proc Biol Sci 2022; 289:20220567. [PMID: 35611538 PMCID: PMC9130785 DOI: 10.1098/rspb.2022.0567] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mate choice informed by the immune genes of the major histocompatibility complex (MHC) may provide fitness benefits including offspring with increased immunocompetence. Olfactory cues are considered the primary mechanism organisms use to evaluate the MHC of potential mates, yet this idea has received limited attention in birds. Motivated by a finding of MHC-dependent mate choice in the Leach's storm-petrel (Oceanodroma leucorhoa), we examined whether the chemical profiles of this highly scented seabird contain information about MHC genes. Whereas previous studies in birds examined non-volatile compounds, we used gas chromatography-mass spectrometry to measure the volatile compounds emitted from feathers that potentially serve as olfactory infochemicals about MHC and coupled this with locus-specific genotyping of MHC IIB genes. We found that feather chemicals reflected individual MHC diversity through interactions with sex and breeding status. Furthermore, similarity in MHC genotype was correlated with similarity in chemical profiles within female-female and male-female dyads. We provide the first evidence that volatile chemicals from bird feathers can encode information about the MHC. Our findings suggest that olfaction likely aids MHC-based mate choice in this species and highlight a role for chemicals in mediating genetic mate choice in birds where this mode of communication has been largely overlooked.
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Affiliation(s)
- Sarah L. Jennings
- Graduate Group in Ecology, University of California Davis, Davis CA 95616, USA
| | - Brian A. Hoover
- Graduate Group in Ecology, University of California Davis, Davis CA 95616, USA,Schmid College of Science and Technology, Chapman University, Orange, CA 92886, USA
| | - Simon Yung Wa Sin
- School of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road, Hong Kong SAR
| | - Susan E. Ebeler
- Graduate Group in Ecology, University of California Davis, Davis CA 95616, USA,Department of Viticulture and Enology, University of California Davis, Davis CA 95616, USA
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4
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Geography is more important than life history in the recent diversification of the tiger salamander complex. Proc Natl Acad Sci U S A 2021; 118:2014719118. [PMID: 33888580 DOI: 10.1073/pnas.2014719118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The North American tiger salamander species complex, including its best-known species, the Mexican axolotl, has long been a source of biological fascination. The complex exhibits a wide range of variation in developmental life history strategies, including populations and individuals that undergo metamorphosis; those able to forego metamorphosis and retain a larval, aquatic lifestyle (i.e., paedomorphosis); and those that do both. The evolution of a paedomorphic life history state is thought to lead to increased population genetic differentiation and ultimately reproductive isolation and speciation, but the degree to which it has shaped population- and species-level divergence is poorly understood. Using a large multilocus dataset from hundreds of samples across North America, we identified genetic clusters across the geographic range of the tiger salamander complex. These clusters often contain a mixture of paedomorphic and metamorphic taxa, indicating that geographic isolation has played a larger role in lineage divergence than paedomorphosis in this system. This conclusion is bolstered by geography-informed analyses indicating no effect of life history strategy on population genetic differentiation and by model-based population genetic analyses demonstrating gene flow between adjacent metamorphic and paedomorphic populations. This fine-scale genetic perspective on life history variation establishes a framework for understanding how plasticity, local adaptation, and gene flow contribute to lineage divergence. Many members of the tiger salamander complex are endangered, and the Mexican axolotl is an important model system in regenerative and biomedical research. Our results chart a course for more informed use of these taxa in experimental, ecological, and conservation research.
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5
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Gagnon M, Yannic G, Boyer F, Côté SD. Adult survival in migratory caribou is negatively associated with MHC functional diversity. Heredity (Edinb) 2020; 125:290-303. [PMID: 32728043 DOI: 10.1038/s41437-020-0347-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 07/04/2020] [Accepted: 07/16/2020] [Indexed: 11/09/2022] Open
Abstract
Genes of the major histocompatibility complex (MHC) are involved in acquired immunity in vertebrates. Only a few studies have investigated the fitness consequences of MHC gene diversity in wild populations. Here, we looked at the association between annual survival and body mass and MHC-DRB exon 2 (MHC-DRB) genetic diversity, obtained from high-throughput sequencing, in two declining migratory caribou (Rangifer tarandus) herds. To disentangle the potential direct and general effects of MHC-DRB genetic diversity, we compared different indices of diversity that were either based on DNA-sequence variation or on physicochemical divergence of the translated peptides, thereby covering a gradient of allelic-to-functional diversity. We found that (1) body mass was not related to MHC-DRB diversity or genotype, and (2) adult survival probability was negatively associated with point accepted mutation distance, a corrected distance that considers the likelihood of each amino acid substitution to be accepted by natural selection. In addition, we found no evidence of fluctuating selection over time on MHC-DRB diversity. We concluded that direct effects were involved in the negative relationship between MHC functional diversity and survival, although the mechanism underlying this result remains unclear. A possible explanation could be that individuals with higher MHC diversity suffer higher costs of immunity (immunopathology). Our results suggest that genetic diversity is not always beneficial even in genes that are likely to be strongly shaped by balancing selection.
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Affiliation(s)
- Marianne Gagnon
- Département de Biologie, Caribou Ungava and Centre d'Études Nordiques, Université Laval, 1045 avenue de la Médecine, Quebec City, QC, G1V 0A6, Canada
| | - Glenn Yannic
- Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA, 38000, Grenoble, France.
| | - Frédéric Boyer
- Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA, 38000, Grenoble, France
| | - Steeve D Côté
- Département de Biologie, Caribou Ungava and Centre d'Études Nordiques, Université Laval, 1045 avenue de la Médecine, Quebec City, QC, G1V 0A6, Canada
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6
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Cayuela H, Valenzuela-Sánchez A, Teulier L, Martínez-Solano Í, Léna JP, Merilä J, Muths E, Shine R, Quay L, Denoël M, Clobert J, Schmidt BR. Determinants and Consequences of Dispersal in Vertebrates with Complex Life Cycles: A Review of Pond-Breeding Amphibians. QUARTERLY REVIEW OF BIOLOGY 2020. [DOI: 10.1086/707862] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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7
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Bentkowski P, Radwan J. Mating preferences can drive expansion or contraction of major histocompatibility complex gene family. Proc Biol Sci 2020; 287:20192706. [PMID: 32097586 DOI: 10.1098/rspb.2019.2706] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Major histocompatibility complex (MHC)-based mating rules can evolve as a way to avoid inbreeding or to increase offspring immune competence. While the role of mating preference in shaping the MHC diversity in vertebrates has been acknowledged, its impact on individual MHC diversity has not been considered. Here, we use computer simulations to investigate how simple mating rules favouring MHC-dissimilar partners affect the evolution of the number of MHC variants in individual genomes, accompanying selection for resistance to parasites. We showed that the effect of such preferences could sometimes be dramatic. If preferences are aimed at avoiding identical alleles, the equilibrium number of MHC alleles is much smaller than under random mating. However, if the mating rule minimizes the ratio of shared to different alleles in partners, MHC number is higher than under random mating. Additionally, our simulations revealed that a negative correlation between the numbers of MHC variants in mated individuals can arise from simple rules of MHC-disassortative mating. Our results reveal unexpected potential of MHC-based mating preferences to drive MHC gene family expansions or contractions and highlight the need to study the mechanistic basis of such preferences, which is currently poorly understood.
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Affiliation(s)
- Piotr Bentkowski
- Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań 61-614, Poland
| | - Jacek Radwan
- Evolutionary Biology Group, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań 61-614, Poland
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8
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Songbirds show odour-based discrimination of similarity and diversity at the major histocompatibility complex. Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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9
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Han QH, Sun RN, Yang HQ, Wang ZW, Wan QH, Fang SG. MHC class I diversity predicts non-random mating in Chinese alligators (Alligator sinensis). Heredity (Edinb) 2019; 122:809-818. [PMID: 30670843 PMCID: PMC6781117 DOI: 10.1038/s41437-018-0177-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/26/2018] [Accepted: 11/28/2018] [Indexed: 11/08/2022] Open
Abstract
The major histocompatibility complex (MHC) has several important roles in kin recognition, pathogen resistance and mate selection. Research in fish, birds and mammals has suggested that individuals optimise MHC diversity, and therefore offspring fitness, when choosing mates. In reptiles, however, it is unclear whether female mate choice is based on genome-wide genetic characteristics such as microsatellite DNA loci, particular functional-trait loci (e.g., MHC) or both, and MHC's effects on mate choice remain relatively understudied. Herein, we used 13 microsatellite loci and two MHC class I loci to investigate female mate choice of Chinese alligators (Alligator sinensis) in the semi-natural condition. We also determined correlations between the MHC genotype of breeding males and male reproductive success. We found that MHC-heterozygous males harbour a greater reproductive success, which probably is the reason that these males are more preferred by the females than MHC-homozygous males. Furthermore, the MHC class I amino-acid distance and functional distance of true mating pairs were higher compared with those of randomly sampled pairs. Analysis of microsatellites revealed that, despite mate choice, females did not completely avoid inbreeding. These findings are the first evidence of MHC-associated mate choice in Chinese alligators, suggesting that females may adopt different mating strategies after assessing the MHC characteristics of potential mates.
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Affiliation(s)
- Qun-Hua Han
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Ru-Na Sun
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Hai-Qiong Yang
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Zhen-Wei Wang
- Changxing Chinese Alligator Nature Reserve, Changxing, 313100, China
| | - Qiu-Hong Wan
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Sheng-Guo Fang
- The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and State Conservation Center for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.
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10
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Slade JWG, Watson MJ, MacDougall‐Shackleton EA. "Balancing" balancing selection? Assortative mating at the major histocompatibility complex despite molecular signatures of balancing selection. Ecol Evol 2019; 9:5146-5157. [PMID: 31110668 PMCID: PMC6509439 DOI: 10.1002/ece3.5087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/19/2019] [Accepted: 03/04/2019] [Indexed: 12/20/2022] Open
Abstract
In vertebrate animals, genes of the major histocompatibility complex (MHC) determine the set of pathogens to which an individual's adaptive immune system can respond. MHC genes are extraordinarily polymorphic, often showing elevated nonsynonymous relative to synonymous sequence variation and sharing presumably ancient polymorphisms between lineages. These patterns likely reflect pathogen-mediated balancing selection, for example, rare-allele or heterozygote advantage. Such selection is often reinforced by disassortative mating at MHC. We characterized exon 2 of MHC class II, corresponding to the hypervariable peptide-binding region, in song sparrows (Melospiza melodia). We compared nonsynonymous to synonymous sequence variation in order to identify positively selected sites; assessed evidence for trans-species polymorphisms indicating ancient balancing selection; and compared MHC similarity of socially mated pairs to expectations under random mating. Six codons showed elevated ratios of nonsynonymous to synonymous variation, consistent with balancing selection, and we characterized several alleles similar to those occurring in at least four other avian families. Despite this evidence for historical balancing selection, mated pairs were significantly more similar at MHC than were randomly generated pairings. Nonrandom mating at MHC thus appears to partially counteract, not reinforce, pathogen-mediated balancing selection in this system. We suggest that in systems where individual fitness does not increase monotonically with MHC diversity, assortative mating may help to avoid excessive offspring heterozygosity that could otherwise arise from long-standing balancing selection.
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Affiliation(s)
- Joel W. G. Slade
- Department of BiologyUniversity of Western OntarioLondonOntarioCanada
| | - Matthew J. Watson
- Department of BiologyUniversity of Western OntarioLondonOntarioCanada
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11
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Swierk L, Langkilde T. Fitness costs of mating with preferred females in a scramble mating system. Behav Ecol 2019. [DOI: 10.1093/beheco/arz001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Abstract
Little is known about the operation of male mate choice in systems with perceived high costs to male choosiness. Scramble mating systems are one type of system in which male choice is often considered too costly to be selected. However, in many scramble mating systems, there are also potentially high rewards of male choosiness, as females vary dramatically in reproductive output and males typically mate once per season and/or per lifetime. Using scramble mating wood frogs (Rana sylvatica), we tested whether males gain fitness benefits by mating with preferred females. We conducted choice trials (1 male presented simultaneously with 2 females) and permitted males to mate with their preferred or nonpreferred female. Offspring of preferred and nonpreferred females were reared in the laboratory and field, and we quantified various fitness-relevant parameters, including survivorship and growth rates. Across multiple parameters measured, matings with preferred females produced fewer and lower-quality offspring than did those with nonpreferred females. Our results are inconsistent with the idea that mate choice confers benefits on the choosing sex. We instead propose that, in scramble systems, males will be more likely to amplex females that are easier to capture, which may correlate with lower quality but increases male likelihood of successfully mating. Such male choice may not favor increased fitness when the operational sex ratio is less biased toward males in scramble mating systems but is, instead, a bet-hedging tactic benefitting males when available females are limited.
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Affiliation(s)
- Lindsey Swierk
- Department of Biology, Intercollege Graduate Program in Ecology, and Center for Brain, Behavior and Cognition, The Pennsylvania State University, PA, USA
| | - Tracy Langkilde
- Department of Biology, Intercollege Graduate Program in Ecology, and Center for Brain, Behavior and Cognition, The Pennsylvania State University, PA, USA
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12
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Abts KC, Ivy JA, DeWoody JA. Demographic, environmental and genetic determinants of mating success in captive koalas (Phascolarctos cinereus). Zoo Biol 2018; 37:416-433. [PMID: 30488502 DOI: 10.1002/zoo.21457] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/29/2018] [Accepted: 10/22/2018] [Indexed: 01/26/2023]
Abstract
Many factors have been shown to affect mating behavior. For instance, genes of the major histocompatibility complex (MHC) are known to influence mate choice in a wide variety of vertebrate species. The genetic management of captive populations can be confounded if intrinsic mate choice reduces or eliminates reproductive success between carefully chosen breeding pairs. For example, the San Diego Zoo koala colony only has a 45% copulation rate for matched individuals. Herein, we investigated determinants of koala mating success using breeding records (1984-2010) and genotypes for 52 individuals at four MHC markers. We quantified MHC diversity according to functional amino acids, heterozygosity, and the probability of producing a heterozygous offspring. We then used categorical analysis and logistic regression to investigate both copulation and parturition success. In addition, we also examined age, day length, and average pairwise kinship. Our post-hoc power analysis indicates that at a power level of 1-β = 0.8, we should have been able to detect strong MHC preferences. However, we did not find a significant MHC effect on either copulation or parturition success with one exception: pairs with lower or no production of a joey had significantly lower MHC functional amino acid diversity in the categorical analysis. In contrast, day length and dam age (or age difference of the pair) consistently had an effect on mating success. These findings may be leveraged to improve the success of attempted pairs, conserve resources, and facilitate genetic management.
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Affiliation(s)
- Kendra C Abts
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana
| | | | - J Andrew DeWoody
- Departments of Forestry and Natural Resources and Biological Sciences, Purdue University, West Lafayette, Indiana
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13
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Hacking JD, Stuart‐Fox D, Godfrey SS, Gardner MG. Specific MHC class I supertype associated with parasite infection and color morph in a wild lizard population. Ecol Evol 2018; 8:9920-9933. [PMID: 30386586 PMCID: PMC6202711 DOI: 10.1002/ece3.4479] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 07/19/2018] [Accepted: 07/23/2018] [Indexed: 12/30/2022] Open
Abstract
The major histocompatibility complex (MHC) is a large gene family that plays a central role in the immune system of all jawed vertebrates. Nonavian reptiles are underrepresented within the MHC literature and little is understood regarding the mechanisms maintaining MHC diversity in this vertebrate group. Here, we examined the relative roles of parasite-mediated selection and sexual selection in maintaining MHC class I diversity of a color polymorphic lizard. We discovered evidence for parasite-mediated selection acting via rare-allele advantage or fluctuating selection as ectoparasite load was significantly lower in the presence of a specific MHC supertype (functional clustering of alleles): supertype four. Based on comparisons between ectoparasite prevalence and load, and assessment of the impact of ectoparasite load on host fitness, we suggest that supertype four confers quantitative resistance to ticks or an intracellular tickborne parasite. We found no evidence for MHC-associated mating in terms of pair genetic distance, number of alleles, or specific supertypes. An association was uncovered between supertype four and male throat color morph. However, it is unlikely that male throat coloration acts as a signal of MHC genotype to conspecifics because we found no evidence to suggest that male throat coloration predicts male mating status. Overall, our results suggest that parasite-mediated selection plays a role in maintaining MHC diversity in this population via rare-allele advantage and/or fluctuating selection. Further work is required to determine whether sexual selection also plays a role in maintaining MHC diversity in agamid lizards.
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Affiliation(s)
- Jessica D. Hacking
- College of Science and EngineeringFlinders UniversityBedford ParkSouth AustraliaAustralia
| | - Devi Stuart‐Fox
- School of BioSciencesUniversity of MelbourneParkvilleVictoriaAustralia
| | | | - Michael G. Gardner
- College of Science and EngineeringFlinders UniversityBedford ParkSouth AustraliaAustralia
- Evolutionary Biology UnitSouth Australian MuseumAdelaideSouth AustraliaAustralia
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14
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Lenz TL, Hafer N, Samonte IE, Yeates SE, Milinski M. Cryptic haplotype-specific gamete selection yields offspring with optimal MHC immune genes. Evolution 2018; 72:2478-2490. [PMID: 30246285 PMCID: PMC6282957 DOI: 10.1111/evo.13591] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 08/13/2018] [Indexed: 12/13/2022]
Abstract
Females choose specific mates in order to produce fitter offspring. However, several factors interfere with females' control over fertilization of their eggs, including sneaker males and phenotypically unpredictable allele segregation during meiosis. Mate choice at the individual level thus provides only a poor approximation for obtaining the best genetic match. Consequently, postcopulatory sperm selection by female oocytes has been proposed as a mechanism to achieve complementary combinations of parental haplotypes. Here, using controlled in vitro fertilization of three‐spined stickleback eggs, we find haplotype‐specific fertilization bias toward gametes with complementary major histocompatibility complex (MHC) immunogenes. The resulting zygote (and thus offspring) genotypes exhibit an intermediate level of individual MHC diversity that was previously shown to confer highest pathogen resistance. Our finding of haplotype‐specific gamete selection thus represents an intriguing mechanism for fine‐tuned optimization of the offspring's immune gene composition and an evolutionary advantage in the Red Queen dynamics of host‐parasite coevolution.
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Affiliation(s)
- Tobias L Lenz
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Nina Hafer
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Irene E Samonte
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Sarah E Yeates
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany.,Current Address: School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Manfred Milinski
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
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15
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Brandies PA, Grueber CE, Ivy JA, Hogg CJ, Belov K. Disentangling the mechanisms of mate choice in a captive koala population. PeerJ 2018; 6:e5438. [PMID: 30155356 PMCID: PMC6108315 DOI: 10.7717/peerj.5438] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 07/23/2018] [Indexed: 11/29/2022] Open
Abstract
Successful captive breeding programs are crucial to the long-term survival of many threatened species. However, pair incompatibility (breeding failure) limits sustainability of many captive populations. Understanding whether the drivers of this incompatibility are behavioral, genetic, or a combination of both, is crucial to improving breeding programs. We used 28 years of pairing data from the San Diego Zoo koala colony, plus genetic analyses using both major histocompatibility complex (MHC)-linked and non-MHC-linked microsatellite markers, to show that both genetic and non-genetic factors can influence mating success. Male age was reconfirmed to be a contributing factor to the likelihood of a koala pair copulating. This trend could also be related to a pair's age difference, which was highly correlated with male age in our dataset. Familiarity was reconfirmed to increase the probability of a successful copulation. Our data provided evidence that females select mates based on MHC and genome-wide similarity. Male heterozygosity at MHC class II loci was associated with both pre- and post-copulatory female choice. Genome-wide similarity, and similarity at the MHC class II DAB locus, were also associated with female choice at the post-copulatory level. Finally, certain MHC-linked alleles were associated with either increased or decreased mating success. We predict that utilizing a variety of behavioral and MHC-dependent mate choice mechanisms improves female fitness through increased reproductive success. This study highlights the complexity of mate choice mechanisms in a species, and the importance of ascertaining mate choice mechanisms to improve the success of captive breeding programs.
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Affiliation(s)
- Parice A. Brandies
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Catherine E. Grueber
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
- San Diego Zoo Global, San Diego, CA, USA
| | | | - Carolyn J. Hogg
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - Katherine Belov
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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16
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Slade JWG, Watson MJ, Kelly TR, Gloor GB, Bernards MA, MacDougall-Shackleton EA. Chemical composition of preen wax reflects major histocompatibility complex similarity in songbirds. Proc Biol Sci 2017; 283:rspb.2016.1966. [PMID: 27807264 DOI: 10.1098/rspb.2016.1966] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 10/07/2016] [Indexed: 12/14/2022] Open
Abstract
In jawed vertebrates, genes of the major histocompatibility complex (MHC) play a key role in immunity by encoding cell-surface proteins that recognize and bind non-self antigens. High variability at MHC suggests that these loci may also function in social signalling such as mate choice and kin recognition. This requires that MHC genotype covaries with some perceptible phenotypic trait. In mammals and fish, MHC is signalled chemically through volatile and non-volatile peptide odour cues, facilitating MHC-dependent mate choice and other behaviours. In birds, despite evidence for MHC-dependent mating, candidate mechanisms for MHC signalling remain largely unexplored. However, feather preen wax has recently been implicated as a potential source of odour cues. We examined whether the chemical composition of preen wax correlates with MHC class IIβ genotypes of wild song sparrows (Melospiza melodia). Pairwise chemical distance reflected amino acid distance at MHC for male-female dyads, although not for same-sex dyads. Chemical diversity did not reflect MHC diversity. We used gas chromatography-mass spectrometry (GC-MS) to characterize preen wax compounds, and identified four wax esters that best reflect MHC similarity. Provided songbirds can detect variation in preen wax composition, this cue may allow individuals to assess MHC compatibility of potential mates.
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Affiliation(s)
- J W G Slade
- Biology, University of Western Ontario London, Ontario, Canada N6A 5B7
| | - M J Watson
- Biology, University of Western Ontario London, Ontario, Canada N6A 5B7
| | - T R Kelly
- Biology, University of Western Ontario London, Ontario, Canada N6A 5B7
| | - G B Gloor
- Biochemistry, University of Western Ontario London, Ontario, Canada N6A 5B7
| | - M A Bernards
- Biology, University of Western Ontario London, Ontario, Canada N6A 5B7
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Cayuela H, Léna JP, Lengagne T, Kaufmann B, Mondy N, Konecny L, Dumet A, Vienney A, Joly P. Relatedness predicts male mating success in a pond-breeding amphibian. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.05.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Moshkin MP, Gerlinskaya LA. Energetic metabolism, stress, and immunity—development of population physiology. BIOL BULL+ 2017. [DOI: 10.1134/s1062359016110108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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19
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Rymešová D, Králová T, Promerová M, Bryja J, Tomášek O, Svobodová J, Šmilauer P, Šálek M, Albrecht T. Mate choice for major histocompatibility complex complementarity in a strictly monogamous bird, the grey partridge ( Perdix perdix). Front Zool 2017; 14:9. [PMID: 28239400 PMCID: PMC5312559 DOI: 10.1186/s12983-017-0194-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 02/01/2017] [Indexed: 11/17/2022] Open
Abstract
Background Sexual selection has been hypothesised as favouring mate choice resulting in production of viable offspring with genotypes providing high pathogen resistance. Specific pathogen recognition is mediated by genes of the major histocompatibility complex (MHC) encoding proteins fundamental for adaptive immune response in jawed vertebrates. MHC genes may also play a role in odour-based individual recognition and mate choice, aimed at avoiding inbreeding. MHC genes are known to be involved in mate choice in a number of species, with ‘good genes’ (absolute criteria) and ‘complementary genes’ (self-referential criteria) being used to explain MHC-based mating. Here, we focus on the effect of morphological traits and variation and genetic similarity between individuals in MHC class IIB (MHCIIB) exon 2 on mating in a free-living population of a monogamous bird, the grey partridge. Results We found no evidence for absolute mate choice criteria as regards grey partridge MHCIIB genotypes, i.e., number and occurrence of amino acid variants, though red chroma of the spot behind eyes was positively associated with male pairing success. On the other hand, mate choice at MHCIIB was based on relative criteria as females preferentially paired with more dissimilar males having a lower number of shared amino acid variants. This observation supports the ‘inbreeding avoidance’ and ‘complementary genes’ hypotheses. Conclusions Our study provides one of the first pieces of evidence for MHC-based mate choice for genetic complementarity in a strictly monogamous bird. The statistical approach employed can be recommended for testing mating preferences in cases where availability of potential mates (recorded with an appropriate method such as radio-tracking) shows considerable temporal variation. Additional genetic analyses using neutral markers may detect whether MHC-based mate choice for complementarity emerges as a by-product of general inbreeding avoidance in grey partridges. Electronic supplementary material The online version of this article (doi:10.1186/s12983-017-0194-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dana Rymešová
- Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 21 Prague 6, Czech Republic.,Department of Botany and Zoology, Faculty of Science, Masaryk University, Czech Republic, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Tereza Králová
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Czech Republic, Kotlářská 2, 611 37 Brno, Czech Republic.,Institute of Vertebrate Biology, The Czech Academy of Sciences, Květná 8, 603 65 Brno, Czech Republic
| | - Marta Promerová
- Institute of Vertebrate Biology, The Czech Academy of Sciences, Květná 8, 603 65 Brno, Czech Republic.,Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-75236 Uppsala, Sweden
| | - Josef Bryja
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Czech Republic, Kotlářská 2, 611 37 Brno, Czech Republic.,Institute of Vertebrate Biology, The Czech Academy of Sciences, Květná 8, 603 65 Brno, Czech Republic
| | - Oldřich Tomášek
- Institute of Vertebrate Biology, The Czech Academy of Sciences, Květná 8, 603 65 Brno, Czech Republic.,Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44 Prague 2, Czech Republic
| | - Jana Svobodová
- Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 21 Prague 6, Czech Republic
| | - Petr Šmilauer
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05 České Budějovice, Czech Republic
| | - Miroslav Šálek
- Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 21 Prague 6, Czech Republic
| | - Tomáš Albrecht
- Institute of Vertebrate Biology, The Czech Academy of Sciences, Květná 8, 603 65 Brno, Czech Republic.,Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, 128 44 Prague 2, Czech Republic
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20
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Schultzhaus JN, Nixon JJ, Duran JA, Carney GE. Diet alters Drosophila melanogaster mate preference and attractiveness. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2016.11.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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21
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Hoover B, Nevitt G. Modeling the Importance of Sample Size in Relation to Error in MHC-Based Mate-Choice Studies on Natural Populations. Integr Comp Biol 2016; 56:925-933. [DOI: 10.1093/icb/icw105] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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22
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Burger D, Dolivo G, Marti E, Sieme H, Wedekind C. Female major histocompatibility complex type affects male testosterone levels and sperm number in the horse (Equus caballus). Proc Biol Sci 2016; 282:20150407. [PMID: 25904670 DOI: 10.1098/rspb.2015.0407] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Odours of vertebrates often contain information about the major histocompatibility complex (MHC), and are used in kin recognition, mate choice or female investment in pregnancy. It is, however, still unclear whether MHC-linked signals can also affect male reproductive strategies. We used horses (Equus caballus) to study this question under experimental conditions. Twelve stallions were individually exposed either to an unfamiliar MHC-similar mare and then to an unfamiliar MHC-dissimilar mare, or vice versa. Each exposure lasted over a period of four weeks. Peripheral blood testosterone levels were determined weekly. Three ejaculates each were collected in the week after exposure to both mares (i.e. in the ninth week) to determine mean sperm number and sperm velocity. We found high testosterone levels when stallions were kept close to MHC-dissimilar mares and significantly lower ones when kept close to MHC-similar mares. Mean sperm number per ejaculate (but not sperm velocity) was positively correlated to mean testosterone levels and also affected by the order of presentation of mares: sperm numbers were higher if MHC-dissimilar mares were presented last than if MHC-similar mares were presented last. We conclude that MHC-linked signals influence testosterone secretion and semen characteristics, two indicators of male reproductive strategies.
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Affiliation(s)
- D Burger
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, Avenches, Switzerland
| | - G Dolivo
- Swiss Institute of Equine Medicine, Agroscope and University of Berne, Avenches, Switzerland
| | - E Marti
- Department of Clinical Research, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - H Sieme
- Unit for Reproductive Medicine-Clinic for Horses, University of Veterinary Medicine Hannover, Hannover, Germany
| | - C Wedekind
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
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23
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Galaverni M, Caniglia R, Milanesi P, Lapalombella S, Fabbri E, Randi E. Choosy Wolves? Heterozygote Advantage But No Evidence of MHC-Based Disassortative Mating. J Hered 2015; 107:134-42. [PMID: 26610365 DOI: 10.1093/jhered/esv090] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/27/2015] [Indexed: 11/13/2022] Open
Abstract
A variety of nonrandom mate choice strategies, including disassortative mating, are used by vertebrate species to avoid inbreeding, maintain heterozygosity and increase fitness. Disassortative mating may be mediated by the major histocompatibility complex (MHC), an important gene cluster controlling immune responses to pathogens. We investigated the patterns of mate choice in 26 wild-living breeding pairs of gray wolf (Canis lupus) that were identified through noninvasive genetic methods and genotyped at 3 MHC class II and 12 autosomal microsatellite (STR) loci. We tested for deviations from random mating and evaluated the covariance of genetic variables at functional and STR markers with fitness proxies deduced from pedigree reconstructions. Results did not show evidences of MHC-based disassortative mating. Rather we found a higher peptide similarity between mates at MHC loci as compared with random expectations. Fitness values were positively correlated with heterozygosity of the breeders at both MHC and STR loci, whereas they decreased with relatedness at STRs. These findings may indicate fitness advantages for breeders that, while avoiding highly related mates, are more similar at the MHC and have high levels of heterozygosity overall. Such a pattern of MHC-assortative mating may reflect local coadaptation of the breeders, while a reduction in genetic diversity may be balanced by heterozygote advantages.
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Affiliation(s)
- Marco Galaverni
- From the Laboratorio di genetica, ISPRA, via Cà Fornacetta 9, 40064 Ozzano dell'Emilia (Bologna), Italy (Galaverni, Caniglia, Milanesi, Fabbri, and Randi); Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via Selmi 3, 40126 Bologna, Italy (Lapalombella); and Department 18/Section of Environmental Engineering, Aalborg University, 9220 Aalborg, Denmark (Randi).
| | - Romolo Caniglia
- From the Laboratorio di genetica, ISPRA, via Cà Fornacetta 9, 40064 Ozzano dell'Emilia (Bologna), Italy (Galaverni, Caniglia, Milanesi, Fabbri, and Randi); Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via Selmi 3, 40126 Bologna, Italy (Lapalombella); and Department 18/Section of Environmental Engineering, Aalborg University, 9220 Aalborg, Denmark (Randi)
| | - Pietro Milanesi
- From the Laboratorio di genetica, ISPRA, via Cà Fornacetta 9, 40064 Ozzano dell'Emilia (Bologna), Italy (Galaverni, Caniglia, Milanesi, Fabbri, and Randi); Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via Selmi 3, 40126 Bologna, Italy (Lapalombella); and Department 18/Section of Environmental Engineering, Aalborg University, 9220 Aalborg, Denmark (Randi)
| | - Silvana Lapalombella
- From the Laboratorio di genetica, ISPRA, via Cà Fornacetta 9, 40064 Ozzano dell'Emilia (Bologna), Italy (Galaverni, Caniglia, Milanesi, Fabbri, and Randi); Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via Selmi 3, 40126 Bologna, Italy (Lapalombella); and Department 18/Section of Environmental Engineering, Aalborg University, 9220 Aalborg, Denmark (Randi)
| | - Elena Fabbri
- From the Laboratorio di genetica, ISPRA, via Cà Fornacetta 9, 40064 Ozzano dell'Emilia (Bologna), Italy (Galaverni, Caniglia, Milanesi, Fabbri, and Randi); Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via Selmi 3, 40126 Bologna, Italy (Lapalombella); and Department 18/Section of Environmental Engineering, Aalborg University, 9220 Aalborg, Denmark (Randi)
| | - Ettore Randi
- From the Laboratorio di genetica, ISPRA, via Cà Fornacetta 9, 40064 Ozzano dell'Emilia (Bologna), Italy (Galaverni, Caniglia, Milanesi, Fabbri, and Randi); Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Via Selmi 3, 40126 Bologna, Italy (Lapalombella); and Department 18/Section of Environmental Engineering, Aalborg University, 9220 Aalborg, Denmark (Randi)
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24
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Croshaw D, Pechmann J. Size does not matter for male Marbled Salamanders (Ambystoma opacum). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Understanding the phenotypic attributes that contribute to variance in mating and reproductive success is crucial in the study of evolution by sexual selection. In many animals, body size is an important trait because larger individuals enjoy greater fitness due to the ability to secure more mates and produce more offspring. Among males, this outcome is largely mediated by greater success in competition with rival males and (or) advantages in attractiveness to females. Here we tested the hypothesis that large male Marbled Salamanders (Ambystoma opacum (Gravenhorst, 1807)) mate with more females and produce more offspring than small males. In experimental breeding groups, we included males chosen specifically to represent a range of sizes. After gravid females mated and nested freely, we collected egg clutches and genotyped all adults and samples of hatchlings with highly variable microsatellite markers to assign paternity. Size had little effect on male mating and reproductive success. Breeding males were not bigger than nonbreeding males, mates of polyandrous females were not smaller than those of monogamous females, and there was no evidence for positive assortative mating by size. Although body size did not matter for male Marbled Salamanders, we documented considerable fitness variation and discuss alternative traits that could be undergoing sexual selection.
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Affiliation(s)
- D.A. Croshaw
- Department of Biological Sciences, Florida Gulf Coast University, Fort Myers, FL 33965, USA; Savannah River Ecology Laboratory, PO Drawer E, Aiken, SC 29802, USA
| | - J.H.K. Pechmann
- Department of Biological Sciences, Western Carolina University, Cullowhee, NC 28723, USA
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25
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Mable BK, Kilbride E, Viney ME, Tinsley RC. Copy number variation and genetic diversity of MHC Class IIb alleles in an alien population of Xenopus laevis. Immunogenetics 2015; 67:591-603. [PMID: 26329765 PMCID: PMC4572066 DOI: 10.1007/s00251-015-0860-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 07/10/2015] [Indexed: 12/23/2022]
Abstract
Xenopus laevis (the African clawed frog), which originated through hybridisation and whole genome duplication, has been used as a model for genetics and development for many years, but surprisingly little is known about immune gene variation in natural populations. The purpose of this study was to use an isolated population of X. laevis that was introduced to Wales, UK in the past 50 years to investigate how variation at the MHC compares to that at other loci, following a severe population bottleneck. Among 18 individuals, we found nine alleles based on exon 2 sequences of the Class IIb region (which includes the peptide binding region). Individuals carried from one to three of the loci identified from previous laboratory studies. Genetic variation was an order of magnitude higher at the MHC compared with three single-copy nuclear genes, but all loci showed high levels of heterozygosity and nucleotide diversity and there was not an excess of homozygosity or decrease in diversity over time that would suggest extensive inbreeding in the introduced population. Tajima’s D was positive for all loci, which is consistent with a bottleneck. Moreover, comparison with published sequences identified the source of the introduced population as the Western Cape region of South Africa, where most commercial suppliers have obtained their stocks. These factors suggest that despite founding by potentially already inbred individuals, the alien population in Wales has maintained substantial genetic variation at both adaptively important and neutral genes.
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Affiliation(s)
- Barbara K Mable
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Elizabeth Kilbride
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Mark E Viney
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK.
| | - Richard C Tinsley
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
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26
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Eddy SL, Vaccaro EA, Baggett CL, Kiemnec-Tyburczy KM, Houck LD. Sperm Mass Longevity and Sperm Storage in the Female Reproductive Tract ofPlethodon shermani(Amphibia: Plethodontidae). HERPETOLOGICA 2015. [DOI: 10.1655/herpetologica-d-14-00059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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27
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Sin YW, Annavi G, Newman C, Buesching C, Burke T, Macdonald DW, Dugdale HL. MHC class II-assortative mate choice in European badgers (Meles meles). Mol Ecol 2015; 24:3138-50. [DOI: 10.1111/mec.13217] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 04/22/2015] [Accepted: 04/23/2015] [Indexed: 01/17/2023]
Affiliation(s)
- Yung Wa Sin
- Wildlife Conservation Research Unit (WildCRU); Department of Zoology; Recanati-Kaplan Centre; University of Oxford; Tubney House Abingdon Road Abingdon Oxfordshire OX13 5QL UK
- NERC Biomolecular Analysis Facility; Department of Animal and Plant Sciences; University of Sheffield; Western Bank; Sheffield South Yorkshire S10 2TN UK
- Department of Organismic and Evolutionary Biology; Museum of Comparative Zoology; Harvard University; 26 Oxford Street Cambridge MA 02138 USA
| | - Geetha Annavi
- Wildlife Conservation Research Unit (WildCRU); Department of Zoology; Recanati-Kaplan Centre; University of Oxford; Tubney House Abingdon Road Abingdon Oxfordshire OX13 5QL UK
- NERC Biomolecular Analysis Facility; Department of Animal and Plant Sciences; University of Sheffield; Western Bank; Sheffield South Yorkshire S10 2TN UK
- Biology Department; Faculty of Science; Universiti Putra Malaysia; 43400 UPM Serdang Selangor Darul Ehsan Malaysia
| | - Chris Newman
- Wildlife Conservation Research Unit (WildCRU); Department of Zoology; Recanati-Kaplan Centre; University of Oxford; Tubney House Abingdon Road Abingdon Oxfordshire OX13 5QL UK
| | - Christina Buesching
- Wildlife Conservation Research Unit (WildCRU); Department of Zoology; Recanati-Kaplan Centre; University of Oxford; Tubney House Abingdon Road Abingdon Oxfordshire OX13 5QL UK
| | - Terry Burke
- NERC Biomolecular Analysis Facility; Department of Animal and Plant Sciences; University of Sheffield; Western Bank; Sheffield South Yorkshire S10 2TN UK
| | - David W. Macdonald
- Wildlife Conservation Research Unit (WildCRU); Department of Zoology; Recanati-Kaplan Centre; University of Oxford; Tubney House Abingdon Road Abingdon Oxfordshire OX13 5QL UK
| | - Hannah L. Dugdale
- NERC Biomolecular Analysis Facility; Department of Animal and Plant Sciences; University of Sheffield; Western Bank; Sheffield South Yorkshire S10 2TN UK
- Groningen Institute for Evolutionary Life Sciences; University of Groningen; PO Box 11103 9700CC Groningen the Netherlands
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28
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Tracy KE, Kiemnec-Tyburczy KM, DeWoody JA, Parra-Olea G, Zamudio KR. Positive selection drives the evolution of a major histocompatibility complex gene in an endangered Mexican salamander species complex. Immunogenetics 2015; 67:323-35. [PMID: 25846208 DOI: 10.1007/s00251-015-0835-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 03/12/2015] [Indexed: 11/30/2022]
Abstract
Immune gene evolution can be critical to species survival in the face of infectious disease. In particular, polymorphism in the genes of the major histocompatibility complex (MHC) helps vertebrates combat novel and diverse pathogens by increasing the number of pathogen-derived proteins that can initiate the host's acquired immune response. In this study, we used a combination of presumably adaptive and neutral markers to investigate MHC evolution in populations of five salamander species within the Ambystoma velasci complex, a group consisting of 15 recently diverged species, several of which are endangered. We isolated 31 unique MHC class II β alleles from 75 total individuals from five species in this complex. MHC heterozygosity was significantly lower than expected for all five species, and we found no clear relationship between number of MHC alleles and species range, life history, or level of heterozygosity. We inferred a phylogeny representing the evolutionary history of Ambystoma MHC, with which we found signatures of positive selection on the overall gene, putative peptide-binding residues, and allelic lineages. We identified several instances of trans-species polymorphism, a hallmark of balancing selection observed in other groups of closely related species. In contrast, we did not detect comparable allelic diversity or signatures of selection on neutral loci. Additionally, we identified 17 supertypes among the 44 unique Ambystoma alleles, indicating that these sequences may encode functionally distinct MHC variants. We therefore have strong evidence that positive selection is a major evolutionary force driving patterns of MHC polymorphism in this recently radiated species complex.
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Affiliation(s)
- Karen E Tracy
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA,
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30
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Abts KC, Ivy JA, DeWoody JA. Immunomics of the koala (Phascolarctos cinereus). Immunogenetics 2015; 67:305-21. [PMID: 25761531 DOI: 10.1007/s00251-015-0833-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 02/19/2015] [Indexed: 12/20/2022]
Abstract
The study of the koala transcriptome has the potential to advance our understanding of its immunome--immunological reaction of a given host to foreign antigens--and to help combat infectious diseases (e.g., chlamydiosis) that impede ongoing conservation efforts. We used Illumina sequencing of cDNA to characterize genes expressed in two different koala tissues of immunological importance, blood and spleen. We generated nearly 600 million raw sequence reads, and about 285 million of these were subsequently assembled and condensed into ~70,000 subcomponents that represent putative transcripts. We annotated ~16% of these subcomponents and identified those related to infection and the immune response, including Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), major histocompatibility complex (MHC) genes, and koala retrovirus (KoRV). Using phylogenetic analyses, we identified 29 koala genes in these target categories and report their concordance with currently accepted gene groups. By mapping multiple sequencing reads to transcripts, we identified 56 putative SNPs in genes of interest. The distribution of these SNPs indicates that MHC genes (34 SNPs) are more diverse than KoRV (12 SNPs), TLRs (8 SNPs), or RLRs (2 SNPs). Our sequence data also indicate that KoRV sequences are highly expressed in the transcriptome. Our efforts have produced full-length sequences for potentially important immune genes in koala, which should serve as targets for future investigations that aim to conserve koala populations.
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Affiliation(s)
- Kendra C Abts
- Department of Forestry and Natural Resources, Purdue University, 195 Marsteller St, West Lafayette, IN, 47907, USA,
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31
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Kamiya T, O'Dwyer K, Westerdahl H, Senior A, Nakagawa S. A quantitative review of MHC-based mating preference: the role of diversity and dissimilarity. Mol Ecol 2014; 23:5151-63. [DOI: 10.1111/mec.12934] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 09/04/2014] [Accepted: 09/17/2014] [Indexed: 11/30/2022]
Affiliation(s)
- T. Kamiya
- Laboratoire MIVEGEC (UMR CNRS 5290, UR IRD 224, UM1, UM2); 911 avenue Agropolis, BP 64501 Montpellier Cedex 5 34394 France
| | - K. O'Dwyer
- Department of Zoology; University of Otago; 360 Great King Street Dunedin New Zealand
| | - H. Westerdahl
- Molecular Ecology and Evolution Lab; Department of Biology; Lund University; SE-223 62 Lund Sweden
| | - A. Senior
- The Charles Perkins Center; The University of Sydney; Sydney NSW 2006 Australia
- School of Biological Sciences; The University of Sydney; Sydney NSW 2006 Australia
| | - S. Nakagawa
- Department of Zoology; University of Otago; 360 Great King Street Dunedin New Zealand
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32
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Plough LV, Moran A, Marko P. Density drives polyandry and relatedness influences paternal success in the Pacific gooseneck barnacle, Pollicipes elegans. BMC Evol Biol 2014; 14:81. [PMID: 24739102 PMCID: PMC4021092 DOI: 10.1186/1471-2148-14-81] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 03/31/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Polyandry is a common mating strategy in animals, increasing female fitness through direct (material) and indirect (genetic) benefits. Most theories about the benefits of polyandry come from studies of terrestrial animals, which have relatively complex mating systems and behaviors; less is known about the potential benefits of polyandry in sessile marine animals, for which potential mates may be scarce and females have less control over pre-copulatory mate choice. Here, we used microsatellite markers to examine multiple paternity in natural aggregations of the Pacific gooseneck barnacle Pollicipes elegans, testing the effect of density on paternity and mate relatedness on male reproductive success. RESULTS We found that multiple paternity was very common (79% of broods), with up to five fathers contributing to a brood, though power was relatively low to detect more than four fathers. Density had a significant and positive linear effect on the number of fathers siring a brood, though this relationship leveled off at high numbers of fathers, which may reflect a lack of power and/or an upper limit to polyandry in this species. Significant skew in male reproductive contribution in multiply-sired broods was observed and we found a positive and significant relationship between the proportion of offspring sired and the genetic similarity between mates, suggesting that genetic compatibility may influence reproductive success in this species. CONCLUSIONS To our knowledge, this is the first study to show high levels of multiple paternity in a barnacle, and overall, patterns of paternity in P. elegans appear to be driven primarily by mate availability. Evidence of paternity bias for males with higher relatedness suggests some form of post-copulatory sexual selection is taking place, but more work is needed to determine whether it operates during or post-fertilization. Overall, our results suggest that while polyandry in P. elegans is driven by mate availability, it may also provide a mechanism for females to ensure fertilization by compatible gametes and increase reproductive success in this sessile species.
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Affiliation(s)
- Louis V Plough
- Horn Point Laboratory, University of Maryland Center for Environmental Science, P,O, Box 775, Cambridge, MD 21601, USA.
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Caspers BA, Krause ET, Hendrix R, Kopp M, Rupp O, Rosentreter K, Steinfartz S. The more the better - polyandry and genetic similarity are positively linked to reproductive success in a natural population of terrestrial salamanders (Salamandra salamandra). Mol Ecol 2013; 23:239-50. [PMID: 24168518 DOI: 10.1111/mec.12577] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 09/09/2013] [Accepted: 10/13/2013] [Indexed: 11/30/2022]
Abstract
Although classically thought to be rare, female polyandry is widespread and may entail significant fitness benefits. If females store sperm over extended periods of time, the consequences of polyandry will depend on the pattern of sperm storage, and some of the potential benefits of polyandry can only be realized if sperm from different males is mixed. Our study aimed to determine patterns and consequences of polyandry in an amphibian species, the fire salamander, under fully natural conditions. Fire salamanders are ideal study objects, because mating, fertilization and larval deposition are temporally decoupled, females store sperm for several months, and larvae are deposited in the order of fertilization. Based on 18 microsatellite loci, we conducted paternity analysis of 24 female-offspring arrays with, in total, over 600 larvae fertilized under complete natural conditions. More than one-third of females were polyandrous and up to four males were found as sires. Our data clearly show that sperm from multiple males is mixed in the female's spermatheca. Nevertheless, paternity is biased, and the most successful male sires on average 70% of the larvae, suggesting a 'topping off' mechanism with first-male precedence. Female reproductive success increased with the number of sires, most probably because multiple mating ensured high fertilization success. In contrast, offspring number was unaffected by female condition and genetic characteristics, but surprisingly, it increased with the degree of genetic relatedness between females and their sires. Sires of polyandrous females tended to be genetically similar to each other, indicating a role for active female choice.
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Affiliation(s)
- Barbara A Caspers
- Department of Animal Behaviour, Bielefeld University, Morgenbreede 45, 33615, Bielefeld, Germany
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Frasier TR, Gillett RM, Hamilton PK, Brown MW, Kraus SD, White BN. Postcopulatory selection for dissimilar gametes maintains heterozygosity in the endangered North Atlantic right whale. Ecol Evol 2013; 3:3483-94. [PMID: 24223284 PMCID: PMC3797493 DOI: 10.1002/ece3.738] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 11/09/2022] Open
Abstract
Although small populations are expected to lose genetic diversity through genetic drift and inbreeding, a number of mechanisms exist that could minimize this genetic decline. Examples include mate choice for unrelated mates and fertilization patterns biased toward genetically dissimilar gametes. Both processes have been widely documented, but the long-term implications have received little attention. Here, we combined over 25 years of field data with high-resolution genetic data to assess the long-term impacts of biased fertilization patterns in the endangered North Atlantic right whale. Offspring have higher levels of microsatellite heterozygosity than expected from this gene pool (effect size = 0.326, P < 0.011). This pattern is not due to precopulatory mate choice for genetically dissimilar mates (P < 0.600), but instead results from postcopulatory selection for gametes that are genetically dissimilar (effect size = 0.37, P < 0.003). The long-term implication is that heterozygosity has slowly increased in calves born throughout the study period, as opposed to the slight decline that was expected. Therefore, this mechanism represents a natural means through which small populations can mitigate the loss of genetic diversity over time.
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Affiliation(s)
- T R Frasier
- Department of Biology and Forensic Sciences Program, Saint Mary's University 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada
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Thiel A, Weeda AC, de Boer JG, Hoffmeister TS. Genetic incompatibility drives mate choice in a parasitic wasp. Front Zool 2013; 10:43. [PMID: 23895372 PMCID: PMC3734144 DOI: 10.1186/1742-9994-10-43] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 07/26/2013] [Indexed: 11/10/2022] Open
Abstract
Introduction Allelic incompatibility between individuals of the same species should select for mate choice based on the genetic make-up of both partners at loci that influence offspring fitness. As a consequence, mate choice may be an important driver of allelic diversity. A complementary sex determination (CSD) system is responsible for intraspecific allelic incompatibility in many species of ants, bees, and wasps. CSD may thus favour disassortative mating and in this, resembles the MHC of the vertebrate immune system, or the self-incompatibility (SI) system of higher plants. Results Here we show that in the monogamous parasitic wasp Bracon brevicornis (Wesmael), females are able to reject partners with incompatible alleles. Forcing females to accept initially rejected partners resulted in sex ratio distortion and partial infertility of offspring. Conclusions CSD-disassortative mating occurred independent of kin recognition and inbreeding avoidance in our experiment. The fitness consequences of mate choice are directly observable, not influenced by environmental effects, and more severe than in comparable systems (SI or MHC), on individuals as well as at the population level. Our results thus demonstrate the strong potential of female mate choice for maintaining high offspring fitness in this species.
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Affiliation(s)
- Andra Thiel
- Population and Evolutionary Ecology, Institute of Ecology, University of Bremen, FB 2, Leobener Str, NW2, 28359 Bremen, Germany.
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Huchard E, Baniel A, Schliehe-Diecks S, Kappeler PM. MHC-disassortative mate choice and inbreeding avoidance in a solitary primate. Mol Ecol 2013; 22:4071-86. [DOI: 10.1111/mec.12349] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/03/2013] [Accepted: 04/09/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Elise Huchard
- Behavioral Ecology and Sociobiology Unit; German Primate Center; Kellnerweg 4 Göttingen Germany
- Courant Research Centre Evolution of Social Behaviour; University of Göttingen; Kellnerweg 6 Göttingen Germany
| | - Alice Baniel
- Behavioral Ecology and Sociobiology Unit; German Primate Center; Kellnerweg 4 Göttingen Germany
| | - Susanne Schliehe-Diecks
- Behavioral Ecology and Sociobiology Unit; German Primate Center; Kellnerweg 4 Göttingen Germany
- Courant Research Centre Evolution of Social Behaviour; University of Göttingen; Kellnerweg 6 Göttingen Germany
| | - Peter M. Kappeler
- Behavioral Ecology and Sociobiology Unit; German Primate Center; Kellnerweg 4 Göttingen Germany
- Courant Research Centre Evolution of Social Behaviour; University of Göttingen; Kellnerweg 6 Göttingen Germany
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Promerová M, Králová T, Bryjová A, Albrecht T, Bryja J. MHC class IIB exon 2 polymorphism in the Grey partridge (Perdix perdix) is shaped by selection, recombination and gene conversion. PLoS One 2013; 8:e69135. [PMID: 23935938 PMCID: PMC3720538 DOI: 10.1371/journal.pone.0069135] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 06/04/2013] [Indexed: 11/19/2022] Open
Abstract
Among bird species, the most studied major histocompatibility complex (MHC) is the chicken MHC. Although the number of studies on MHC in free-ranging species is increasing, the knowledge on MHC variation in species closely related to chicken is required to understand the peculiarities of bird MHC evolution. Here we describe the variation of MHC class IIB (MHCIIB) exon 2 in a population of the Grey partridge (Perdix perdix), a species of high conservation concern throughout Europe and an emerging galliform model in studies of sexual selection. We found 12 alleles in 108 individuals, but in comparison to other birds surprisingly many sites show signatures of historical positive selection. Individuals displayed between two to four alleles both on genomic and complementary DNA, suggesting the presence of two functional MHCIIB loci. Recombination and gene conversion appear to be involved in generating MHCIIB diversity in the Grey partridge; two recombination breakpoints and several gene conversion events were detected. In phylogenetic analysis of galliform MHCIIB, the Grey partridge alleles do not cluster together, but are scattered through the tree instead. Thus, our results indicate that the Grey partridge MHCIIB is comparable to most other galliforms in terms of copy number and population polymorphism.
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Affiliation(s)
- Marta Promerová
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Tereza Králová
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Anna Bryjová
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Tomáš Albrecht
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Josef Bryja
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
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Bollmer JL, Dunn PO, Freeman-Gallant CR, Whittingham LA. Social and extra-pair mating in relation to major histocompatibility complex variation in common yellowthroats. Proc Biol Sci 2012; 279:4778-85. [PMID: 23055067 DOI: 10.1098/rspb.2012.1885] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Females are thought to gain better-quality genes for their offspring by mating with particular males. Genes of the major histocompatibility complex (MHC) play a critical role in adaptive immunity, and several studies have examined female mate choice in relation to MHC variation. In common yellowthroats, females prefer males that have larger black facial masks, an ornament associated with MHC variation, immune function and condition. Here we also tested whether mating patterns are directly correlated with MHC diversity or similarity. Using pyrosequencing, we found that the presence of extra-pair young in the brood was not related to male MHC diversity or similarity between the female and her within-pair mate. Furthermore, extra-pair sires did not differ in overall diversity from males they cuckolded, or in their similarity to the female. MHC diversity is extremely high in this species, and it may limit the ability of females to assess MHC variation in males. Thus, mating may be based on ornaments, such as mask size, which are better indicators of overall male health and genetic quality.
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Affiliation(s)
- Jennifer L Bollmer
- Department of Biological Sciences, Behavioral and Molecular Ecology Group, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
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Bird KL, Aldridge CL, Carpenter JE, Paszkowski CA, Boyce MS, Coltman DW. The secret sex lives of sage-grouse: multiple paternity and intraspecific nest parasitism revealed through genetic analysis. Behav Ecol 2012. [DOI: 10.1093/beheco/ars132] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Eo SH, Dewoody JA. The effects of contig length and depth on the estimation of SNP frequencies, and the relative abundance of SNPs in protein-coding and non-coding transcripts of tiger salamanders (Ambystoma tigrinum). BMC Genomics 2012; 13:259. [PMID: 22716167 PMCID: PMC3416719 DOI: 10.1186/1471-2164-13-259] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 06/20/2012] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Next-generation sequencing methods have contributed to rapid progress in the fields of genomics and population genetics. Using this high-throughput and cost-effective technology, a number of studies have estimated single nucleotide polymorphism (SNP) frequency by calculating the mean number of SNPs per unit sequence length (e.g., mean SNPs/kb). However, both read length and contig depth are highly variable and thus raise doubt about simple methods of SNP frequency estimation. RESULTS We used 454 pyrosequencing to identify 2,980 putative SNPs in the eastern tiger salamander (Ambystoma tigrinum tigrinum) transcriptome, then constructed analytical models to estimate SNP frequency. The model which considered only contig length (i.e., the method employed in most published papers) was evaluated with very poor likelihood. Our most robust model considered read depth as well as contig length, and was 7.5 × 10⁵⁵ times more likely than the length-only model. Using this novel modeling approach, we estimated SNP frequency in protein-coding (mRNA) and non-coding transcripts (e.g., small RNAs). We found little difference in SNP frequency in the contigs, but we found a trend of a higher frequency of SNPs in long contigs representing non-coding transcripts relative to protein-coding transcripts. These results support the hypothesis that long non-coding transcripts are less conserved than long protein-coding transcripts. CONCLUSIONS A modeling approach (i.e., using multiple model construction and model selection approaches) can be a powerful tool for identifying selection on specific functional sequence groups by comparing the frequency and distribution of polymorphisms.
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Affiliation(s)
- Soo Hyung Eo
- Department of Forestry & Natural Resources, Purdue University, West Lafayette, IN 47907, USA.
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41
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Baratti M, Dessì-Fulgheri F, Ambrosini R, Bonisoli-Alquati A, Caprioli M, Goti E, Matteo A, Monnanni R, Ragionieri L, Ristori E, Romano M, Rubolini D, Scialpi A, Saino N. MHC genotype predicts mate choice in the ring-necked pheasant Phasianus colchicus. J Evol Biol 2012; 25:1531-42. [PMID: 22591334 DOI: 10.1111/j.1420-9101.2012.02534.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Females of several vertebrate species selectively mate with males on the basis of the major histocompatibility complex (MHC) genes. As androgen-mediated maternal effects have long-lasting consequences for the adult phenotype, both mating and reproductive success may depend on the combined effect of MHC genotype and exposure to androgens during early ontogeny. We studied how MHC-based mate choice in ring-necked pheasants (Phasianus colchicus) was influenced by an experimental in ovo testosterone (T) increase. There was no conclusive evidence of in ovo T treatment differentially affecting mate choice in relation to MHC genotype. However, females avoided mating with males with a wholly different MHC genotype compared with males sharing at least one MHC allele. Females also tended to avoid mating with MHC-identical males, though not significantly so. These findings suggest that female pheasants preferred males with intermediate MHC dissimilarity. Male MHC heterozygosity or diversity did not predict the expression of ornaments or male dominance rank. Thus, MHC-based mating preferences in the ring-necked pheasant do not seem to be mediated by ornaments' expression and may have evolved mainly to reduce the costs of high heterozygosity at MHC loci for the progeny, such as increased risk of autoimmune diseases or disruption of coadapted gene pools.
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Affiliation(s)
- M Baratti
- Istituto per lo Studio degli Ecosistemi, Sesto Fiorentino, via Madonna del Piano 10, Florence, Italy.
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Martinez-Padilla J, Vergara P, Mougeot F, Redpath SM. Parasitized mates increase infection risk for partners. Am Nat 2012; 179:811-20. [PMID: 22617268 DOI: 10.1086/665664] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Individuals can gain fitness benefits and costs through their mates. However, studies on sexual selection have tended to focus on genetic benefits. A potentially widespread cost of pairing with a parasitized mate is that doing so will increase an individual's parasite abundance. Such a cost has been overlooked in systems in which parasites are indirectly transmitted. We manipulated the abundance of the nematode parasite Trichostrongylus tenuis, an indirectly transmitted parasite, within pairs of wild red grouse Lagopus lagopus scoticus in spring. Parasite levels were correlated within pairs before the experiment. We removed parasites from males, females, or both members of the pair and evaluated individual parasite uptake over the subsequent breeding period. At the end of the breeding season, an individual's parasite abundance was greater when its mate had not been initially purged of parasites. This cost appeared to be greater for males. We discuss the implications of our results in relation to the costs that parasites may have on sexual selection processes.
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Affiliation(s)
- Jesus Martinez-Padilla
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (CSIC), José Gutiérrez Abascal 2, 28006 Madrid, Spain.
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Ruff JS, Nelson AC, Kubinak JL, Potts WK. MHC signaling during social communication. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 738:290-313. [PMID: 22399386 PMCID: PMC4835215 DOI: 10.1007/978-1-4614-1680-7_17] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The major histocompatibility complex (MHC) has been known to play a critical role in immune recognition since the 1950s. It was a surprise, then, in the 1970s when the first report appeared indicating MHC might also function in social signaling. Since this seminal discovery, MHC signaling has been found throughout vertebrates and its known functions have expanded beyond mate choice to include a suite of behaviors from kin-biased cooperation, parent-progeny recognition to pregnancy block. The widespread occurrence of MHC in social signaling has revealed conserved behavioral-genetic mechanisms that span vertebrates and includes humans. The identity of the signal's chemical constituents and the receptors responsible for the perception of the signal have remained elusive, but recent advances have enabled the identification of the key components of the behavioral circuit. In this chapter we organize recent findings from the literature and discuss them in relation to four nonmutually exclusive models wherein MHC functions as a signal of (i) individuality, (ii) relatedness, (iii) genetic compatibility and (iv) quality. We also synthesize current mechanistic studies, showing how knowledge about the molecular basis of MHC signaling can lead to elegant and informative experimental manipulations. Finally, we discuss current evidence relating to the primordial functions of the MHC, including the possibility that its role in social signaling may be ancestral to its central role in adaptive immunity.
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Affiliation(s)
- James S Ruff
- Department of Biology, University of Utah, Salt Lake City, UT, USA.
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Comparative transcriptomics and gene expression in larval tiger salamander (Ambystoma tigrinum) gill and lung tissues as revealed by pyrosequencing. Gene 2011; 492:329-38. [PMID: 22138480 DOI: 10.1016/j.gene.2011.11.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 10/21/2011] [Accepted: 11/10/2011] [Indexed: 01/15/2023]
Abstract
Biologists are beginning to unravel the complexities of gene expression in model organisms by studying the transcriptome, the complement of genes that are transcribed in a given tissue. It is unclear, however, if findings from model systems apply to non-model organisms because of environmental effects on gene expression. Furthermore, there have been few efforts to quantify how transcriptome or gene expression varies across individuals and across tissues in natural environments. Herein, we describe transcriptomic profiling of gene expression in lung and gill tissue of three larval tiger salamanders. We do so with a hierarchical experimental design that captures variation in expression among genes, among tissues, and among individuals. Using 454 pyrosequencing, we produced high-quality sequence data of 59 megabases and assembled ~200,000 reads into 19,501 contigs. These contigs BLASTed to 3,599 transcripts, of which 721 were expressed in both tissues, 1,668 were unique to gill, and 1,210 unique to lung. Our data showed tissue-specific patterns in gene expression level with variation among transcripts and individuals. We identified genes and gene ontology terms related to respiration and compared their relative expression levels between gill and lung tissues. We also found evidence of exogenous genes associated with larval salamanders, and we identified ~1400 potential molecular markers (microsatellites and single nucleotide polymorphisms) that are associated with expressed genes. Given the tissue-specific differences we observed in transcriptomes, these data reinforce the idea that changes in gene expression serve as a primary mechanism underlying phenotypic plasticity.
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Jacob A, Evanno G, Von Siebenthal BA, Grossen C, Wedekind C. Effects of different mating scenarios on embryo viability in brown trout. Mol Ecol 2010; 19:5296-307. [PMID: 21040055 DOI: 10.1111/j.1365-294x.2010.04884.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Mating with attractive or dominant males is often predicted to offer indirect genetic benefits to females, but it is still largely unclear how important such non-random mating can be with regard to embryo viability. We sampled a natural population of adult migratory brown trout (Salmo trutta), bred them in vitro in a half-sib breeding design to separate genetic from maternal environmental effects, raised 2098 embryos singly until hatching, and exposed them experimentally to different levels of pathogen stress at a late embryonic stage. We found that the embryos' tolerance to the induced pathogen stress was linked to the major histocompatibility complex (MHC) of their parents, i.e. certain MHC genotypes appeared to provide better protection against infection than others. We also found significant additive genetic variance for stress tolerance. Melanin-based dark skin patterns revealed males with 'good genes', i.e. embryos fathered by dark coloured males had a high tolerance to infection. Mating with large and dominant males would, however, not improve embryo viability when compared to random mating. We used simulations to provide estimates of how mate choice based on MHC or melanin-based skin patterns would influence embryos' tolerance to the experimentally induced pathogen stress.
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Affiliation(s)
- Alain Jacob
- Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland
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Ziegler A, Santos PSC, Kellermann T, Uchanska-Ziegler B. Self/nonself perception, reproduction and the extended MHC. SELF NONSELF 2010; 1:176-191. [PMID: 21487476 DOI: 10.4161/self.1.3.12736] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 06/21/2010] [Indexed: 01/01/2023]
Abstract
Self/nonself perception governs mate selection in most eukaryotic species. It relies on a number of natural barriers that act before, during and after copulation. These hurdles prevent a costly investment into an embryo with potentially suboptimal genetic and immunological properties and aim at discouraging fertilization when male and female gametes exhibit extensive sharing of alleles. Due to the fact that several genes belonging to the extended major histocompatibility complex (xMHC) carry out crucial immune functions and are the most polymorphic within vertebrate genomes, it is likely that securing heterozygosity and the selection of rare alleles within this gene complex contributes to endowing the offspring with an advantage in fighting infections. Apart from MHC class I and II antigens, the products of several other genes within the xMHC are candidates for participating in mate choice, especially since the respective loci are subject to long-range linkage disequilibrium which may aid to preserve functionally connected alleles within a given haplotype. Among these loci are polymorphic odorant receptor genes that are expressed not only in the olfactory epithelium, but also within male reproductive tissues. They may thus not only be of importance in olfaction-influenced mate choice, by recognizing MHC-dependent individual-specific olfactory signals, but could also guide spermatozoa along chemical gradients to their target, the oocyte. By focusing on the human HLA complex and genes within its vicinity, we show here that the products of several xMHC-specified molecules might be involved in self/nonself perception during reproduction. Although the molecular details are often unknown, the existence of highly diverse, yet intertwined pre- and post-copulatory barriers suggests that xMHC-encoded proteins may be important for various stages of mate choice, germ cell development, as well as embryonic and foetal life in mammals and other vertebrates. Many of these genes should thus be regarded as crucial not only within the immune system, but also in reproduction.
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Affiliation(s)
- Andreas Ziegler
- Institut für Immungenetik; Charité-Universitätsmedizin Berlin; Campus Benjamin Franklin; Freie Universität Berlin; Berlin, Germany
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Huchard E, Knapp LA, Wang J, Raymond M, Cowlishaw G. MHC, mate choice and heterozygote advantage in a wild social primate. Mol Ecol 2010; 19:2545-61. [PMID: 20492522 DOI: 10.1111/j.1365-294x.2010.04644.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Preferences for mates carrying dissimilar genes at the major histocompatibility complex (MHC) may help animals increase offspring pathogen resistance or avoid inbreeding. Such preferences have been reported across a range of vertebrates, but have rarely been investigated in social species other than humans. We investigated mate choice and MHC dynamics in wild baboons (Papio ursinus). MHC Class II DRB genes and 16 microsatellite loci were genotyped across six groups (199 individuals). Based on the survey of a key segment of the gene-rich MHC, we found no evidence of mate choice for MHC dissimilarity, diversity or rare MHC genotypes. First, MHC dissimilarity did not differ from random expectation either between parents of the same offspring or between immigrant males and females from the same troop. Second, female reproductive success was not influenced by MHC diversity or genotype frequency. Third, population genetic structure analysis revealed equally high genotypic differentiation among troops, and comparable excess heterozygosity within troops for juveniles, at both Mhc-DRB and neutral loci. Nevertheless, the age structure of Mhc-DRB heterozygosity suggested higher longevity for heterozygotes, which should favour preferences for MHC dissimilarity. We propose that high levels of within-group outbreeding, resulting from group-living and sex-biased dispersal, might weaken selection for MHC-disassortative mate choice.
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Affiliation(s)
- Elise Huchard
- CNRS-UMR5554, Place Eugène Bataillon, CC 065, 34 095 Montpellier Cedex 5, France.
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Lenz TL, Eizaguirre C, Scharsack JP, Kalbe M, Milinski M. Disentangling the role of MHC-dependent 'good genes' and 'compatible genes' in mate-choice decisions of three-spined sticklebacks Gasterosteus aculeatus under semi-natural conditions. JOURNAL OF FISH BIOLOGY 2009; 75:2122-2142. [PMID: 20738677 DOI: 10.1111/j.1095-8649.2009.02410.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
To investigate and disentangle the role of major histocompatibility complex (MHC)-based 'good genes' and 'compatible genes' in mate choice, three-spined sticklebacks Gasterosteus aculeatus with specific MHC IIB genotypes were allowed to reproduce in an outdoor enclosure system. Here, fish were protected from predators but encountered their natural parasites. Mate choice for an intermediate genetic distance between parental MHC genotypes was observed, which would result in intermediate diversity in the offspring, but no mate choice based on good genes was found under the current semi-natural conditions. Investigation of immunological variables revealed that the less-specific innate immune system was more active in individuals with a genetically more divergent MHC allele repertoire. This suggests the need to compensate for an MHC-diminished T-cell repertoire and potentially explains the observed mate choice for intermediate MHC genetic distance. The present findings support a general pattern of mate choice for intermediate MHC diversity (i.e. compatible genes). In addition, the potentially dynamic role of MHC good genes in mate choice under different parasite pressures is discussed in the light of present and previous results.
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Affiliation(s)
- T L Lenz
- Max Planck Institute for Evolutionary Biology, Department of Evolutionary Ecology, August-Thienemann-Str. 2, 24306 Plön, Germany.
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Abstract
There is now substantial and growing evidence for a role of the major histocompatibility complex (MHC) in shaping individual mate preferences. In view of both its codominant expression and its function in immune response, it is often expected that females aim to avoid inbreeding or maximize offspring MHC-heterozygosity by selecting as mates those males which share fewest or no MHC alleles with themselves. However, it is becoming increasingly clear that this view is over-simplistic: not only is MHC dissimilarity just one of several (perhaps many) criteria important in mate choice decision-making, extremely MHC-dissimilar males may be avoided, and furthermore, specific alleles or combinations might be preferred if they bestow particular advantages. These points are raised in two papers in this Molecular Ecology issue, in which patterns of reproductive success in tiger salamanders (Ambystoma tigrinum) and three-spined sticklebacks (Gasterosteus aculeatus) are each inconsistent with a generalized preference for MHC dissimilarity. Together, these studies demonstrate several adaptive reasons for decision rules that do not necessarily result in maximizing mate dissimilarity.
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Affiliation(s)
- S Craig Roberts
- School of Biological Sciences, University of Liverpool, Liverpool, UK.
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