151
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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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152
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Ihle M, Forstmeier W. Revisiting the evidence for inbreeding avoidance in zebra finches. Behav Ecol 2013. [DOI: 10.1093/beheco/art074] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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153
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The Major Histocompatibility Complex and Primate Behavioral Ecology: New Tools and Future Questions. INT J PRIMATOL 2013. [DOI: 10.1007/s10764-013-9700-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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154
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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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155
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Laeng B, Vermeer O, Sulutvedt U. Is beauty in the face of the beholder? PLoS One 2013; 8:e68395. [PMID: 23874608 PMCID: PMC3707967 DOI: 10.1371/journal.pone.0068395] [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: 04/02/2013] [Accepted: 05/28/2013] [Indexed: 11/22/2022] Open
Abstract
Opposing forces influence assortative mating so that one seeks a similar mate while at the same time avoiding inbreeding with close relatives. Thus, mate choice may be a balancing of phenotypic similarity and dissimilarity between partners. In the present study, we assessed the role of resemblance to Self's facial traits in judgments of physical attractiveness. Participants chose the most attractive face image of their romantic partner among several variants, where the faces were morphed so as to include only 22% of another face. Participants distinctly preferred a "Self-based morph" (i.e., their partner's face with a small amount of Self's face blended into it) to other morphed images. The Self-based morph was also preferred to the morph of their partner's face blended with the partner's same-sex "prototype", although the latter face was ("objectively") judged more attractive by other individuals. When ranking morphs differing in level of amalgamation (i.e., 11% vs. 22% vs. 33%) of another face, the 22% was chosen consistently as the preferred morph and, in particular, when Self was blended in the partner's face. A forced-choice signal-detection paradigm showed that the effect of self-resemblance operated at an unconscious level, since the same participants were unable to detect the presence of their own faces in the above morphs. We concluded that individuals, if given the opportunity, seek to promote "positive assortment" for Self's phenotype, especially when the level of similarity approaches an optimal point that is similar to Self without causing a conscious acknowledgment of the similarity.
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Affiliation(s)
- Bruno Laeng
- Department of Psychology, University of Oslo, Oslo, Norway
| | - Oddrun Vermeer
- Department of Psychology, University of Tromsø, Tromsø, Norway
| | - Unni Sulutvedt
- Department of Psychology, University of Oslo, Oslo, Norway
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156
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Barclay VC. Variation in host resistance could limit the spread of more broadly virulent pathogens. Virulence 2013; 4:347-9. [PMID: 23689611 PMCID: PMC3714125 DOI: 10.4161/viru.25061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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157
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Collin H, Burri R, Comtesse F, Fumagalli L. Combining molecular evolution and environmental genomics to unravel adaptive processes of MHC class IIB diversity in European minnows (Phoxinus phoxinus). Ecol Evol 2013; 3:2568-85. [PMID: 24567825 PMCID: PMC3930049 DOI: 10.1002/ece3.650] [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: 03/27/2013] [Revised: 04/26/2013] [Accepted: 04/29/2013] [Indexed: 11/10/2022] Open
Abstract
Host-pathogen interactions are a major evolutionary force promoting local adaptation. Genes of the major histocompatibility complex (MHC) represent unique candidates to investigate evolutionary processes driving local adaptation to parasite communities. The present study aimed at identifying the relative roles of neutral and adaptive processes driving the evolution of MHC class IIB (MHCIIB) genes in natural populations of European minnows (Phoxinus phoxinus). To this end, we isolated and genotyped exon 2 of two MHCIIB gene duplicates (DAB1 and DAB3) and 1'665 amplified fragment length polymorphism (AFLP) markers in nine populations, and characterized local bacterial communities by 16S rDNA barcoding using 454 amplicon sequencing. Both MHCIIB loci exhibited signs of historical balancing selection. Whereas genetic differentiation exceeded that of neutral markers at both loci, the populations' genetic diversities were positively correlated with local pathogen diversities only at DAB3. Overall, our results suggest pathogen-mediated local adaptation in European minnows at both MHCIIB loci. While at DAB1 selection appears to favor different alleles among populations, this is only partially the case in DAB3, which appears to be locally adapted to pathogen communities in terms of genetic diversity. These results provide new insights into the importance of host-pathogen interactions in driving local adaptation in the European minnow, and highlight that the importance of adaptive processes driving MHCIIB gene evolution may differ among duplicates within species, presumably as a consequence of alternative selective regimes or different genomic context. Using next-generation sequencing, the present manuscript identifies the relative roles of neutral and adaptive processes driving the evolution of MHC class IIB (MHCIIB) genes in natural populations of a cyprinid fish: the European minnow (Phoxinus phoxinus). We highlight that the relative importance of neutral versus adaptive processes in shaping immune competence may differ between duplicates as a consequence of alternative selective regimes or different genomic contexts.
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Affiliation(s)
- Helene Collin
- Department of Ecology and Evolution Laboratory for Conservation Biology, University of Lausanne Biophore, 1015, Lausanne, Switzerland ; Institute of Integrative Biology, University of Liverpool Biosciences Building, Crown St., Liverpool L69 7ZB, U.K
| | - Reto Burri
- Department of Ecology and Evolution Laboratory for Conservation Biology, University of Lausanne Biophore, 1015, Lausanne, Switzerland ; Department of Evolutionary Biology Evolutionary Biology Centre, Uppsala University Norbyvägen 18D, 75236, Uppsala, Sweden
| | - Fabien Comtesse
- Department of Ecology and Evolution Laboratory for Conservation Biology, University of Lausanne Biophore, 1015, Lausanne, Switzerland
| | - Luca Fumagalli
- Department of Ecology and Evolution Laboratory for Conservation Biology, University of Lausanne Biophore, 1015, Lausanne, Switzerland
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158
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Šimková A, Civáňová K, Gettová L, Gilles A. Genomic Porosity between Invasive Chondrostoma nasus and Endangered Endemic Parachondrostoma toxostoma (Cyprinidae): The Evolution of MHC IIB Genes. PLoS One 2013; 8:e65883. [PMID: 23824831 PMCID: PMC3688810 DOI: 10.1371/journal.pone.0065883] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/30/2013] [Indexed: 02/06/2023] Open
Abstract
Two cyprinid species, Parachondrostoma toxostoma, an endemic threatened species, and Chondrostoma nasus, an invasive species, live in sympatry in southern France and form two sympatric zones where the presence of intergeneric hybrids is reported. To estimate the potential threat to endemic species linked to the introduction of invasive species, we focused on the DAB genes (functional MHC IIB genes) because of their adaptive significance and role in parasite resistance. More specifically, we investigated (1) the variability of MHC IIB genes, (2) the selection pattern shaping MHC polymorphism, and (3) the extent to which trans-species evolution and intergeneric hybridization affect MHC polymorphism. In sympatric areas, the native species has more diversified MHC IIB genes when compared to the invasive species, probably resulting from the different origins and dispersal of both species. A similar level of MHC polymorphism was found at population level in both species, suggesting similar mechanisms generating MHC diversity. In contrast, a higher number of DAB-like alleles per specimen were found in invasive species. Invasive species tended to express the alleles of two DAB lineages, whilst native species tended to express the alleles of only the DAB3 lineage. Hybrids have a pattern of MHC expression intermediate between both species. Whilst positive selection acting on peptide binding sites (PBS) was demonstrated in both species, a slightly higher number of positively selected sites were identified in C. nasus, which could result from parasite-mediated selection. Bayesian clustering analysis revealed a similar pattern of structuring for the genetic variation when using microsatellites or the MHC approach. We confirmed the importance of trans-species evolution for MHC polymorphism. In addition, we demonstrated bidirectional gene flow for MHC IIB genes in sympatric areas. The positive significant correlation between MHC and microsatellites suggests that demographic factors may contribute to MHC variation on a short time scale.
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Affiliation(s)
- Andrea Šimková
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Kristína Civáňová
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Lenka Gettová
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - André Gilles
- Aix-Marseille Université, Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale, UMR Centre national de la recherche scientifique 7263, Evolution Génome Environnement, Marseille, France
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159
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Šimková A, Košař M, Vetešník L, Vyskočilová M. MHC genes and parasitism in Carassius gibelio, a diploid-triploid fish species with dual reproduction strategies. BMC Evol Biol 2013; 13:122. [PMID: 23768177 PMCID: PMC3691641 DOI: 10.1186/1471-2148-13-122] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 06/06/2013] [Indexed: 11/10/2022] Open
Abstract
Background The gibel carp is a fish species with dual reproduction modes, gynogenesis and sexual reproduction, coexisting in mixed diploid-polyploid populations. Following the Red Queen (RQ) assumption, asexual organisms are, due to their low genetic diversity, targets for parasite adaptation. Because MHC polymorphism is maintained by selection from parasites and sexual selection, MHC genes are considered as a suitable candidate for testing the RQ hypothesis. In this study, we investigated MHC variability and the selection pressure acting on MHC genes in sexual diploids and asexual triploids. In addition, we tested whether the asexual form of gibel carp suffers from higher parasite loads than the sexual form. Results At the population level, genotype and allelic diversity of MHC were reduced in gynogenetic triploids when compared to sexual diploids. Different patterns in positively selected sites (PSS) between gynogens and sexual gibel carp were also found. A weak difference in parasite species richness was found between sexual fish and gynogens. However, two common clones of gynogens were significantly more parasitized than sexual diploids or other gynogens with rare MHC genotypes. At the individual level, the higher number of alleles was not associated with higher parasitism in either sexual diploids or gynogens. Conclusions The differences in MHC diversity between gynogenetic triploids and sexual diploids are in accordance with the hypothesis of sexually-mediated selection increasing MHC diversity and fulfil a prerequisite of the Red Queen hypothesis. The different patterns in PSS between gynogens and sexual gibel carp also suggest the potential role of sexual selection and supports parasite-mediated selection maintaining MHC diversity. We showed that the most common MHC genotypes of gynogenetic triploids are the target of parasite selection. Our results suggest that the MHC genotype in gibel carp is more important than allelic number for immunocompetence.
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Affiliation(s)
- Andrea Šimková
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, Brno 611 37, Czech Republic.
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160
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Kubinak JL, Ruff JS, Cornwall DH, Middlebrook EA, Hasenkrug KJ, Potts WK. Experimental viral evolution reveals major histocompatibility complex polymorphisms as the primary host factors controlling pathogen adaptation and virulence. Genes Immun 2013; 14:365-72. [PMID: 23698707 DOI: 10.1038/gene.2013.27] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 04/03/2013] [Accepted: 04/05/2013] [Indexed: 02/05/2023]
Abstract
Using an experimental evolution approach, we recently demonstrated that the mouse-specific pathogen Friend virus (FV) complex adapted to specific major histocompatibility complex (MHC) genotypes, which resulted in fitness tradeoffs when viruses were exposed to hosts possessing novel MHC polymorphisms. Here we report the analysis of patterns of pathogen adaptation and virulence evolution from viruses adapting to one of three hosts that differ across the entire genome (A/WySn, DBA/2J and BALB/c). We found that serial passage of FV complex through these mouse genotypes resulted in significant increases in pathogen fitness (156-fold) and virulence (11-fold). Adaptive responses by post-passage viruses also resulted in host-genotype-specific patterns of adaptation. To evaluate the relative importance of MHC versus non-MHC polymorphisms as factors influencing pathogen adaptation and virulence, we compared the magnitude of fitness tradeoffs incurred by post-passage viruses when infecting hosts possessing either novel MHC polymorphisms alone or hosts possessing novel MHC and non-MHC polymorphisms. MHC polymorphisms alone accounted for 71% and 83% of the total observed reductions in viral fitness and virulence in unfamiliar host genotypes, respectively. Strikingly, these data suggest that genetic polymorphisms within the MHC, a gene region representing only -0.1% of the genome, are major host factors influencing pathogen adaptation and virulence evolution.
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Affiliation(s)
- J L Kubinak
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA.
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161
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Setchell JM, Abbott KM, Gonzalez JP, Knapp LA. Testing for post-copulatory selection for major histocompatibility complex genotype in a semi-free-ranging primate population. Am J Primatol 2013; 75:1021-31. [PMID: 23677678 DOI: 10.1002/ajp.22166] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 04/09/2013] [Accepted: 04/17/2013] [Indexed: 11/09/2022]
Abstract
A large body of evidence suggests that major histocompatibility complex (MHC) genotype influences mate choice. However, few studies have investigated MHC-mediated post-copulatory mate choice under natural, or even semi-natural, conditions. We set out to explore this question in a large semi-free-ranging population of mandrills (Mandrillus sphinx) using MHC-DRB genotypes for 127 parent-offspring triads. First, we showed that offspring MHC heterozygosity correlates positively with parental MHC dissimilarity suggesting that mating among MHC dissimilar mates is efficient in increasing offspring MHC diversity. Second, we compared the haplotypes of the parental dyad with those of the offspring to test whether post-copulatory sexual selection favored offspring with two different MHC haplotypes, more diverse gamete combinations, or greater within-haplotype diversity. Limited statistical power meant that we could only detect medium or large effect sizes. Nevertheless, we found no evidence for selection for heterozygous offspring when parents share a haplotype (large effect size), genetic dissimilarity between parental haplotypes (we could detect an odds ratio of ≥1.86), or within-haplotype diversity (medium-large effect). These findings suggest that comparing parental and offspring haplotypes may be a useful approach to test for post-copulatory selection when matings cannot be observed, as is the case in many study systems. However, it will be extremely difficult to determine conclusively whether post-copulatory selection mechanisms for MHC genotype exist, particularly if the effect sizes are small, due to the difficulty in obtaining a sufficiently large sample.
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Affiliation(s)
- Joanna M Setchell
- Evolutionary Anthropology Research Group, Department of Anthropology, Durham University, Durham, United Kingdom.
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162
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Califf KJ, Ratzloff EK, Wagner AP, Holekamp KE, Williams BL. Forces shaping major histocompatibility complex evolution in two hyena species. J Mammal 2013. [DOI: 10.1644/12-mamm-a-054.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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163
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Osborne MJ, Perez TL, Altenbach CS, Turner TF. Genetic analysis of captive spawning strategies for the endangered Rio Grande Silvery Minnow. J Hered 2013; 104:437-46. [PMID: 23519867 DOI: 10.1093/jhered/est013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Captive breeding and rearing are central elements in conservation, management, and recovery planning for many endangered species including Rio Grande Silvery Minnow, a North American freshwater cyprinid. Traditionally, the sole purpose of hatcheries was to produce as many fish as feasible for stocking and harvest. Production quotas are also an important consideration in hatchery programs for endangered species, but they must also maintain and maximize genetic diversity of fish produced through implementation of best breeding practices. Here, we assessed genetic outcomes and measures of productivity (number of eggs and larval viability) for three replicates of three mating designs that are used for this small, pelagic-spawning fish. These were 1) monogamous mating, 2) hormone-induced communal spawning, and 3) environmentally cued communal spawning. A total of 180 broodstock and 450 progeny were genotyped. Genetic diversity and egg productivity did not differ significantly among spawning designs (H e : F = 0.52, P = 0.67; H o : F = 0.12, P = 0.89; number of eggs: F = 3.59, P = 0.09), and there was evidence for variance in reproductive success among individuals in all three designs. Allelic richness declined from the broodstock to progeny generation in all breeding designs. There was no significant difference in the genetic effective size (regardless of the method used) among designs. Significantly more viable eggs were produced in environmentally cued communal spawn compared to the alternative strategies (F = 5.72, P = 0.04), but this strategy is the most difficult to implement.
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Affiliation(s)
- Megan J Osborne
- Department of Biology and Museum of Southwestern Biology, University of New Mexico, Albuquerque, NM 87131, USA.
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164
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Montero I, Teschke M, Tautz D. Paternal imprinting of mating preferences between natural populations of house mice (Mus musculus domesticus). Mol Ecol 2013; 22:2549-62. [PMID: 23506395 DOI: 10.1111/mec.12271] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 01/04/2013] [Accepted: 01/09/2013] [Indexed: 11/30/2022]
Abstract
The evolutionary divergence of cues for mate recognition can contribute to early stages of population separation. We compare here two allopatric populations of house mice (Mus musculus domesticus) that have become separated about 3000 years ago. We have used paternity assignments in semi-natural environments to study the degree of mutual mate recognition according to population origin under conditions of free choice and overlapping generations. Our results provide insights into the divergence of mating cues, but also for the mating system of house mice. We find frequent multiple mating, occurrence of inbreeding and formation of extended family groups. In addition, many animals show strong mate fidelity, that is, frequent choice of the same mating partners in successive breeding cycles, indicating a role for familiarity in mating preference. With respect to population divergence, we find evidence for assortative mating, but only under conditions where the animals had time to familiarize themselves with mating partners from their own population. Most interestingly, the first-generation offspring born in the enclosure showed a specific mating pattern. Although matings between animals of hybrid population origin with animals of pure population origin should have occurred with equal frequency with respect to matching the paternal or maternal origin, paternal matching with mates from their own populations occurred much more often. Our findings suggest that paternally imprinted cues play a role in mate recognition between mice and that the cues evolve fast, such that animals of populations that are separated since not more than 3000 years can differentially recognize them.
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Affiliation(s)
- Inka Montero
- Max-Planck Institute for Evolutionary Biology, Plön, Germany
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165
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Gohli J, Anmarkrud JA, Johnsen A, Kleven O, Borge T, Lifjeld JT. FEMALE PROMISCUITY IS POSITIVELY ASSOCIATED WITH NEUTRAL AND SELECTED GENETIC DIVERSITY IN PASSERINE BIRDS. Evolution 2013; 67:1406-19. [DOI: 10.1111/evo.12045] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 12/17/2012] [Indexed: 12/16/2022]
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166
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Blouin-Demers G, Lourdais O, Bouazza A, Verreault C, El Mouden H, Slimani T. Patterns of throat colour variation in Quedenfeldtia trachyblepharus, a high-altitude gecko endemic to the High Atlas Mountains of Morocco. AMPHIBIA-REPTILIA 2013. [DOI: 10.1163/15685381-00002900] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The persistence of marked phenotypic variation within species is evolutionarily puzzling. We uncovered remarkable variation in throat colouration in a high-altitude gecko (Atlas Day Gecko, Quedenfeldtia trachyblepharus) endemic to the High Atlas Mountains of Morocco. Orange, yellow, and white variants were found in approximately equal proportions in both sexes, and in juveniles and adults. The colour variants did not differ in body size or in body condition, but there was some indication that orange males have relatively longer jaws than white or yellow males. The number of mites harboured by an individual was not a function of its sex or of its throat colouration, but larger lizards did harbour more mites. Our data do not support the hypotheses that throat colour variation is due to selection pressures differing between the sexes or through ontogeny, or signals immunocompetence, but offer some support for the hypothesis that throat colour variation signals dominance. Future investigations on the evolution of throat colour variation in this species should use spectrophotometry to obtain finer colour classification and incorporate measures of fitness.
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Affiliation(s)
| | - Olivier Lourdais
- 2Centre d’Études Biologiques de Chizé, Centre National de la Recherche Scientifique, Villiers en Bois, 79360 France
| | - Abdellah Bouazza
- 3Laboratoire Biodiversité et Dynamique des Écosystèmes, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, 40 000 Maroc
| | - Catherine Verreault
- 4Parc de la Gatineau, Commission de la Capitale Nationale, Ottawa, Ontario, K1P 1C7 Canada
| | - Hassan El Mouden
- 3Laboratoire Biodiversité et Dynamique des Écosystèmes, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, 40 000 Maroc
| | - Tahar Slimani
- 3Laboratoire Biodiversité et Dynamique des Écosystèmes, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, 40 000 Maroc
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167
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Hinz C, Gebhardt K, Hartmann AK, Sigman L, Gerlach G. Influence of kinship and MHC class II genotype on visual traits in zebrafish larvae (Danio rerio). PLoS One 2012; 7:e51182. [PMID: 23251449 PMCID: PMC3519631 DOI: 10.1371/journal.pone.0051182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 10/31/2012] [Indexed: 11/30/2022] Open
Abstract
Kin recognition can drive kin selection and the evolution of social behaviour. In zebrafish (Danio rerio, Hamilton 1822), kin recognition is based on olfactory and visual imprinting processes. If larvae are exposed to visual and chemical cues of kin at day 5 and 6 post fertilization they will recognize kin throughout life, while exposure to non-kin fails to trigger any recognition. Chemical imprinting signals are transcribed by polymorphic genes of the major histocompatibility complex (MHC) code; however, the underlying mechanism for visual imprinting remains unclear. Here we provide evidence for the existence of family-specific differences in morphometry and pigmentation pattern of six day old zebrafish larvae. While rump, tail and body pigmentation were dependent on relatedness, iris pigmentation and morphometry were also influenced by MHC class II genotype. Our study revealed that the MHC not only influences the chemical signature of individuals, but also their visual appearance.
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Affiliation(s)
- Cornelia Hinz
- Department of Biology and Environmental Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany.
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168
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Sepil I, Lachish S, Sheldon BC. Mhc-linked survival and lifetime reproductive success in a wild population of great tits. Mol Ecol 2012. [DOI: 10.1111/mec.12123] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Irem Sepil
- Department of Zoology; Edward Grey Institute; University of Oxford; South Parks Road Oxford OX1 3PS UK
| | - Shelly Lachish
- Department of Zoology; Edward Grey Institute; University of Oxford; South Parks Road Oxford OX1 3PS UK
| | - Ben C. Sheldon
- Department of Zoology; Edward Grey Institute; University of Oxford; South Parks Road Oxford OX1 3PS UK
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169
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Axtner J, Sommer S. The functional importance of sequence versus expression variability of MHC alleles in parasite resistance. Genetica 2012. [PMID: 23180005 DOI: 10.1007/s10709-012-9689-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Understanding selection processes driving the pronounced allelic polymorphism of the major histocompatibility complex (MHC) genes and its functional associations to parasite load have been the focus of many recent wildlife studies. Two main selection scenarios are currently debated which explain the susceptibility or resistance to parasite infections either by the effects of (1) specific MHC alleles which are selected frequency-dependent in space and time or (2) a heterozygote or divergent allele advantage. So far, most studies have focused only on structural variance in co-evolutionary processes although this might not be the only trait subject to natural selection. In the present study, we analysed structural variance stretching from exon1 through exon3 of MHC class II DRB genes as well as genotypic expression variance in relation to the gastrointestinal helminth prevalence and infection intensity in wild yellow-necked mice (Apodemus flavicollis). We found support for the functional importance of specific alleles both on the sequence and expression level. By resampling a previously investigated study population we identified specific MHC alleles affected by temporal shifts in parasite pressure and recorded associated changes in allele frequencies. The allele Apfl-DRB*23 was associated with resistance to infections by the oxyurid nematode Syphacia stroma and at the same time with susceptibility to cestode infection intensity. In line with our expectation, MHC mRNA transcript levels tended to be higher in cestode-infected animals carrying the allele Apfl-DRB*23. However, no support for a heterozygote or divergent allele advantage on the sequence or expression level was detected. The individual amino acid distance of genotypes did not explain individual differences in parasite loads and the genetic distance had no effect on MHC genotype expression. For ongoing studies on the functional importance of expression variance in parasite resistance, allele-specific expression data would be preferable.
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Affiliation(s)
- Jan Axtner
- Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 15, 10315, Berlin, Germany.
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170
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What Can Phages Tell Us about Host-Pathogen Coevolution? INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:396165. [PMID: 23213618 PMCID: PMC3506893 DOI: 10.1155/2012/396165] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 10/13/2012] [Indexed: 01/16/2023]
Abstract
The outcomes of host-parasite interactions depend on the coevolutionary forces acting upon them, but because every host-parasite relation is enmeshed in a web of biotic and abiotic interactions across a heterogeneous landscape, host-parasite coevolution has proven difficult to study. Simple laboratory phage-bacteria microcosms can ameliorate this difficulty by allowing controlled, well-replicated experiments with a limited number of interactors. Genetic, population, and life history data obtained from these studies permit a closer examination of the fundamental correlates of host-parasite coevolution. In this paper, I describe the results of phage-bacteria coevolutionary studies and their implications for the study of host-parasite coevolution. Recent experimental studies have confirmed phage-host coevolutionary dynamics in the laboratory and have shown that coevolution can increase parasite virulence, specialization, adaptation, and diversity. Genetically, coevolution frequently proceeds in a manner best described by the Gene for Gene model, typified by arms race dynamics, but certain contexts can result in Red Queen dynamics according to the Matching Alleles model. Although some features appear to apply only to phage-bacteria systems, other results are broadly generalizable and apply to all instances of antagonistic coevolution. With laboratory host-parasite coevolutionary studies, we can better understand the perplexing array of interactions that characterize organismal diversity in the wild.
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171
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Pillay N, Rymer TL. Behavioural divergence, interfertility and speciation: A review. Behav Processes 2012; 91:223-35. [DOI: 10.1016/j.beproc.2012.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 08/27/2012] [Indexed: 11/25/2022]
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172
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Sin YW, Dugdale HL, Newman C, Macdonald DW, Burke T. Evolution of MHC class I genes in the European badger (Meles meles). Ecol Evol 2012; 2:1644-62. [PMID: 22957169 PMCID: PMC3434948 DOI: 10.1002/ece3.285] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 04/27/2012] [Indexed: 02/01/2023] Open
Abstract
The major histocompatibility complex (MHC) plays a central role in the adaptive immune system and provides a good model with which to understand the evolutionary processes underlying functional genes. Trans-species polymorphism and orthology are both commonly found in MHC genes; however, mammalian MHC class I genes tend to cluster by species. Concerted evolution has the potential to homogenize different loci, whereas birth-and-death evolution can lead to the loss of orthologs; both processes result in monophyletic groups within species. Studies investigating the evolution of MHC class I genes have been biased toward a few particular taxa and model species. We present the first study of MHC class I genes in a species from the superfamily Musteloidea. The European badger (Meles meles) exhibits moderate variation in MHC class I sequences when compared to other carnivores. We identified seven putatively functional sequences and nine pseudogenes from genomic (gDNA) and complementary (cDNA) DNA, signifying at least two functional class I loci. We found evidence for separate evolutionary histories of the α1 and α2/α3 domains. In the α1 domain, several sequences from different species were more closely related to each other than to sequences from the same species, resembling orthology or trans-species polymorphism. Balancing selection and probable recombination maintain genetic diversity in the α1 domain, evidenced by the detection of positive selection and a recombination event. By comparison, two recombination breakpoints indicate that the α2/α3 domains have most likely undergone concerted evolution, where recombination has homogenized the α2/α3 domains between genes, leading to species-specific clusters of sequences. Our findings highlight the importance of analyzing MHC domains separately.
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Affiliation(s)
- Yung Wa Sin
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan CentreTubney House, Abingdon Road, Tubney, Abingdon, Oxfordshire OX13 5QL, United Kingdom
- NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences, University of SheffieldWestern Bank, Sheffield, South Yorkshire, S10 2TN, United Kingdom
| | - Hannah L Dugdale
- NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences, University of SheffieldWestern Bank, Sheffield, South Yorkshire, S10 2TN, United Kingdom
- Behavioural Ecology and Self-Organization, University of GroningenP.O. Box 11103, 9700 CC Groningen, The Netherlands
- Theoretical Biology, University of GroningenP.O. Box 11103, 9700 CC Groningen, The Netherlands
| | - Chris Newman
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan CentreTubney House, Abingdon Road, Tubney, Abingdon, Oxfordshire OX13 5QL, United Kingdom
| | - David W Macdonald
- Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Recanati-Kaplan CentreTubney House, Abingdon Road, Tubney, Abingdon, Oxfordshire OX13 5QL, United Kingdom
| | - Terry Burke
- NERC Biomolecular Analysis Facility, Department of Animal and Plant Sciences, University of SheffieldWestern Bank, Sheffield, South Yorkshire, S10 2TN, United Kingdom
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173
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Strandh M, Westerdahl H, Pontarp M, Canbäck B, Dubois MP, Miquel C, Taberlet P, Bonadonna F. Major histocompatibility complex class II compatibility, but not class I, predicts mate choice in a bird with highly developed olfaction. Proc Biol Sci 2012; 279:4457-63. [PMID: 22951737 DOI: 10.1098/rspb.2012.1562] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mate choice for major histocompatibility complex (MHC) compatibility has been found in several taxa, although rarely in birds. MHC is a crucial component in adaptive immunity and by choosing an MHC-dissimilar partner, heterozygosity and potentially broad pathogen resistance is maximized in the offspring. The MHC genotype influences odour cues and preferences in mammals and fish and hence olfactory-based mate choice can occur. We tested whether blue petrels, Halobaena caerulea, choose partners based on MHC compatibility. This bird is long-lived, monogamous and can discriminate between individual odours using olfaction, which makes it exceptionally well suited for this analysis. We screened MHC class I and II B alleles in blue petrels using 454-pyrosequencing and quantified the phylogenetic, functional and allele-sharing similarity between individuals. Partners were functionally more dissimilar at the MHC class II B loci than expected from random mating (p = 0.033), whereas there was no such difference at the MHC class I loci. Phylogenetic and non-sequence-based MHC allele-sharing measures detected no MHC dissimilarity between partners for either MHC class I or II B. Our study provides evidence of mate choice for MHC compatibility in a bird with a high dependency on odour cues, suggesting that MHC odour-mediated mate choice occurs in birds.
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Affiliation(s)
- Maria Strandh
- Behavioral Ecology Group, CEFE-CNRS, 1919 Route de Mende, Montpellier Cedex 5, France.
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174
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Knafler GJ, Clark JA, Boersma PD, Bouzat JL. MHC diversity and mate choice in the magellanic penguin, Spheniscus magellanicus. ACTA ACUST UNITED AC 2012; 103:759-68. [PMID: 22952272 DOI: 10.1093/jhered/ess054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We estimated levels of diversity at the major histocompatibility complex (MHC) class II DRß1 gene in 50 breeding pairs of the Magellanic penguin and compared those to estimates from Humboldt and Galapagos penguins. We tested for positive selection and 2 conditions required for the evolution of MHC-based disassortative mating: 1) greater MHC diversity between breeding pairs compared to random mating, and 2) associations between MHC genotype and fitness. Cloning and sequencing of the DRß1 gene showed that Magellanic penguins had higher levels of genetic variation than Galapagos and Humboldt penguins. Sequence analysis revealed 45 alleles with 3.6% average proportion of nucleotide differences, nucleotide diversity of 0.030, and observed heterozygosity of 0.770. A gene phylogeny showed 9 allelic lineages with interspersed DRß1 sequences from Humboldt and Galapagos penguins, indicating ancestral polymorphisms. d (N)/d (S) ratios revealed evidence for positive selection. Analysis of breeding pairs showed no disassortative mating preferences. Significant MHC genotype/fitness associations in females suggest, however, that selection for pathogen resistance plays a more important role than mate choice in maintaining diversity at the MHC in the Magellanic penguin. The differential effect of MHC heterozygosity on fitness between the sexes is likely associated with the relative role of hatching and fledging rates as reliable indicators of overall fitness in males and females.
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175
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Krupp DB, Sewall LA, Lalumière ML, Sheriff C, Harris GT. Nepotistic patterns of violent psychopathy: evidence for adaptation? Front Psychol 2012; 3:305. [PMID: 22973244 PMCID: PMC3428807 DOI: 10.3389/fpsyg.2012.00305] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 08/03/2012] [Indexed: 11/18/2022] Open
Abstract
Psychopaths routinely disregard social norms by engaging in selfish, antisocial, often violent behavior. Commonly characterized as mentally disordered, recent evidence suggests that psychopaths are executing a well-functioning, if unscrupulous strategy that historically increased reproductive success at the expense of others. Natural selection ought to have favored strategies that spared close kin from harm, however, because actions affecting the fitness of genetic relatives contribute to an individual's inclusive fitness. Conversely, there is evidence that mental disorders can disrupt psychological mechanisms designed to protect relatives. Thus, mental disorder and adaptation accounts of psychopathy generate opposing hypotheses: psychopathy should be associated with an increase in the victimization of kin in the former account but not in the latter. Contrary to the mental disorder hypothesis, we show here in a sample of 289 violent offenders that variation in psychopathy predicts a decrease in the genetic relatedness of victims to offenders; that is, psychopathy predicts an increased likelihood of harming non-relatives. Because nepotistic inhibition in violence may be caused by dispersal or kin discrimination, we examined the effects of psychopathy on (1) the dispersal of offenders and their kin and (2) sexual assault frequency (as a window on kin discrimination). Although psychopathy was negatively associated with coresidence with kin and positively associated with the commission of sexual assault, it remained negatively associated with the genetic relatedness of victims to offenders after removing cases of offenders who had coresided with kin and cases of sexual assault from the analyses. These results stand in contrast to models positing psychopathy as a pathology, and provide support for the hypothesis that psychopathy reflects an evolutionary strategy largely favoring the exploitation of non-relatives.
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Affiliation(s)
- Daniel Brian Krupp
- Department of Mathematics and Statistics, Queen’s UniversityKingston, ON, Canada
- Department of Psychology, Neuroscience and Behaviour, McMaster UniversityHamilton, ON, Canada
- Department of Psychology, University of LethbridgeLethbridge, AB, Canada
| | - Lindsay A. Sewall
- Department of Psychology, University of LethbridgeLethbridge, AB, Canada
- Department of Psychology, University of SaskatchewanSaskatoon, SK, Canada
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176
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van Rensburg AJ, Bloomer P, Ryan PG, Hansson B. Ancestral polymorphism at the major histocompatibility complex (MHCIIß) in the Nesospiza bunting species complex and its sister species (Rowettia goughensis). BMC Evol Biol 2012; 12:143. [PMID: 22894748 PMCID: PMC3483275 DOI: 10.1186/1471-2148-12-143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 07/13/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The major histocompatibility complex (MHC) is an important component of the vertebrate immune system and is frequently used to characterise adaptive variation in wild populations due to its co-evolution with pathogens. Passerine birds have an exceptionally diverse MHC with multiple gene copies and large numbers of alleles compared to other avian taxa. The Nesospiza bunting species complex (two species on Nightingale Island; one species with three sub-species on Inaccessible Island) represents a rapid adaptive radiation at a small, isolated archipelago, and is thus an excellent model for the study of adaptation and speciation. In this first study of MHC in Nesospiza buntings, we aim to characterize MHCIIß variation, determine the strength of selection acting at this gene region and assess the level of shared polymorphism between the Nesospiza species complex and its putative sister taxon, Rowettia goughensis, from Gough Island. RESULTS In total, 23 unique alleles were found in 14 Nesospiza and 2 R. goughensis individuals encoding at least four presumably functional loci and two pseudogenes. There was no evidence of ongoing selection on the peptide binding region (PBR). Of the 23 alleles, 15 were found on both the islands inhabited by Nesospiza species, and seven in both Nesospiza and Rowettia; indications of shared, ancestral polymorphism. A gene tree of Nesospiza MHCIIß alleles with several other passerine birds shows three highly supported Nesospiza-specific groups. All R. goughensis alleles were shared with Nesospiza, and these alleles were found in all three Nesospiza sequence groups in the gene tree, suggesting that most of the observed variation predates their phylogenetic split. CONCLUSIONS Lack of evidence of selection on the PBR, together with shared polymorphism across the gene tree, suggests that population variation of MHCIIß among Nesospiza and Rowettia is due to ancestral polymorphism rather than local selective forces. Weak or no selection pressure could be attributed to low parasite load at these isolated Atlantic islands. The deep divergence between the highly supported Nesospiza-specific sequence Groups 2 and 3, and the clustering of Group 3 close to the distantly related passerines, provide strong support for preserved ancestral polymorphism, and present evidence of one of the rare cases of extensive ancestral polymorphism in birds.
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Affiliation(s)
- Alexandra Jansen van Rensburg
- Molecular Ecology and Evolution Program, Department of Genetics, University of Pretoria, Private bag X20, Hatfield, 0028, South Africa
| | - Paulette Bloomer
- Molecular Ecology and Evolution Program, Department of Genetics, University of Pretoria, Private bag X20, Hatfield, 0028, South Africa
| | - Peter G Ryan
- Percy FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch, 7701, South Africa
| | - Bengt Hansson
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, SE-22362, Lund, Sweden
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177
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Tan CK, Løvlie H, Pizzari T, Wigby S. No evidence for precopulatory inbreeding avoidance in Drosophila melanogaster. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.03.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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178
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Tybur JM, Gangestad SW. Mate preferences and infectious disease: theoretical considerations and evidence in humans. Philos Trans R Soc Lond B Biol Sci 2012; 366:3375-88. [PMID: 22042915 DOI: 10.1098/rstb.2011.0136] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mate preferences may operate in part to mitigate the threats posed by infectious disease. In this paper, we outline various ways in which preferring healthy mates can offer direct benefits in terms of pathogen avoidance and indirect benefits in terms of heritable immunity to offspring, as well as the costs that may constrain mate preferences for health. We then pay special attention to empirical work on mate preferences in humans given the depth and breadth of research on human mating. We review this literature and comment on the degree to which human mate preferences may reflect preferences for health.
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Affiliation(s)
- Joshua M Tybur
- Department of Social and Organizational Psychology, VU University Amsterdam, Amsterdam, The Netherlands
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179
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Becker PA, Miller PS, Gunther MS, Somers MJ, Wildt DE, Maldonado JE. Inbreeding avoidance influences the viability of reintroduced populations of African wild dogs (Lycaon pictus). PLoS One 2012; 7:e37181. [PMID: 22615933 PMCID: PMC3353914 DOI: 10.1371/journal.pone.0037181] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 04/17/2012] [Indexed: 11/19/2022] Open
Abstract
The conservation of many fragmented and small populations of endangered African wild dogs (Lycaon pictus) relies on understanding the natural processes affecting genetic diversity, demographics, and future viability. We used extensive behavioural, life-history, and genetic data from reintroduced African wild dogs in South Africa to (1) test for inbreeding avoidance via mate selection and (2) model the potential consequences of avoidance on population persistence. Results suggested that wild dogs avoided mating with kin. Inbreeding was rare in natal packs, after reproductive vacancies, and between sibling cohorts (observed on 0.8%, 12.5%, and 3.8% of occasions, respectively). Only one of the six (16.7%) breeding pairs confirmed as third-order (or closer) kin consisted of animals that were familiar with each other, while no other paired individuals had any prior association. Computer-simulated populations allowed to experience inbreeding had only a 1.6% probability of extinction within 100 years, whereas all populations avoiding incestuous matings became extinct due to the absence of unrelated mates. Populations that avoided mating with first-order relatives became extinct after 63 years compared with persistence of 37 and 19 years for those also prevented from second-order and third-order matings, respectively. Although stronger inbreeding avoidance maintains significantly more genetic variation, our results demonstrate the potentially severe demographic impacts of reduced numbers of suitable mates on the future viability of small, isolated wild dog populations. The rapid rate of population decline suggests that extinction may occur before inbreeding depression is observed.
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Affiliation(s)
- Penny A Becker
- Center for Conservation and Evolutionary Genetics, Smithsonian Conservation Biology Institute, National Zoological Park, Smithsonian Institution, Washington, District of Columbia, United States of America.
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180
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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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181
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Schad J, Dechmann DKN, Voigt CC, Sommer S. Evidence for the 'good genes' model: association of MHC class II DRB alleles with ectoparasitism and reproductive state in the neotropical lesser bulldog bat, Noctilio albiventris. PLoS One 2012; 7:e37101. [PMID: 22615910 PMCID: PMC3353892 DOI: 10.1371/journal.pone.0037101] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 04/18/2012] [Indexed: 11/18/2022] Open
Abstract
The adaptive immune system has a major impact on parasite resistance and life history strategies. Immunological defence is costly both in terms of immediate activation and long-term maintenance. The 'good genes' model predicts that males with genotypes that promote a good disease resistance have the ability to allocate more resources to reproductive effort which favours the transmission of good alleles into future generations. Our study shows a correlation between immune gene constitution (Major Histocompatibility Complex, MHC class II DRB), ectoparasite loads (ticks and bat flies) and the reproductive state in a neotropical bat, Noctilio albiventris. Infestation rates with ectoparasites were linked to specific Noal-DRB alleles, differed among roosts, increased with body size and co-varied with reproductive state particularly in males. Non-reproductive adult males were more infested with ectoparasites than reproductively active males, and they had more often an allele (Noal-DRB*02) associated with a higher tick infestation than reproductively active males or subadults. We conclude that the individual immune gene constitution affects ectoparasite susceptibility, and contributes to fitness relevant trade-offs in male N. albiventris as suggested by the 'good genes' model.
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Affiliation(s)
- Julia Schad
- Leibniz Institute for Zoo and Wildlife Research, Evolutionary Genetics, Berlin, Germany
| | - Dina K. N. Dechmann
- Department of Migration and Immuno-Ecology, Max Planck Institute for Ornithology, Radolfzell, Germany
- Department of Biology, Universität Konstanz, Konstanz, Germany
| | - Christian C. Voigt
- Leibniz Institute for Zoo and Wildlife Research, Evolutionary Ecology, Berlin, Germany
| | - Simone Sommer
- Leibniz Institute for Zoo and Wildlife Research, Evolutionary Genetics, Berlin, Germany
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182
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Abstract
Mating with a member of another species can seriously reduce an organism's fitness, so mechanisms ought to evolve to prevent it where hybridizing species meet. This old idea of 'reinforcement' has found new support in an elegant pair of studies of the ecological genetics of flower colour in an annual herb.
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Affiliation(s)
- John R Pannell
- Department of Ecology and Evolution, University of Lausanne, Lausanne 1015, Switzerland.
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183
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Babik W, Kawałko A, Wójcik JM, Radwan J. Low Major Histocompatibility Complex Class I (MHC I) Variation in the European Bison (Bison bonasus). J Hered 2012; 103:349-59. [DOI: 10.1093/jhered/ess005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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184
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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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185
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Thünken T, Meuthen D, Bakker TCM, Baldauf SA. A sex-specific trade-off between mating preferences for genetic compatibility and body size in a cichlid fish with mutual mate choice. Proc Biol Sci 2012; 279:2959-64. [PMID: 22513859 DOI: 10.1098/rspb.2012.0333] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mating preferences for genetic compatibility strictly depend on the interplay of the genotypes of potential partners and are therein fundamentally different from directional preferences for ornamental secondary sexual traits. Thus, the most compatible partner is on average not the one with most pronounced ornaments and vice versa. Hence, mating preferences may often conflict. Here, we present a solution to this problem while investigating the interplay of mating preferences for relatedness (a compatibility criterion) and large body size (an ornamental or quality trait). In previous experiments, both sexes of Pelvicachromis taeniatus, a cichlid fish with mutual mate choice, showed preferences for kin and large partners when these criteria were tested separately. In the present study, test fish were given a conflicting choice between two potential mating partners differing in relatedness as well as in body size in such a way that preferences for both criteria could not simultaneously be satisfied. We show that a sex-specific trade-off occurs between mating preferences for body size and relatedness. For females, relatedness gained greater importance than body size, whereas the opposite was true for males. We discuss the potential role of the interplay between mating preferences for relatedness and body size for the evolution of inbreeding preference.
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Affiliation(s)
- Timo Thünken
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121 Bonn, Germany.
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186
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Knapp LA, Innocent SHS. Molecules and mating: positive selection and reproductive behaviour in primates. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 739:218-36. [PMID: 22399405 DOI: 10.1007/978-1-4614-1704-0_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Sexual reproduction is generally thought to be more costly than asexual reproduction. However, it does have the advantage of accelerating rates of adaptation through processes such as recombination and positive selection. Comparative studies of the human and nonhuman primate genomes have demonstrated that positive selection has played an important role in the evolutionary history of humans and other primates. To date, many dozens of genes, thought to be affected by positive selection, have been identified. In this chapter, we will focus on genes that are associated with mating behaviours and reproductive processes, concentrating on genes that are most likely to enhance reproductive success and that also show evidence of positive selection. The genes encode phenotypic features that potentially influence mate choice decisions or impact the evolution and function of genes involved in the perception and regulation of, and the response to, phenotypic signals. We will also consider genes that influence precopulatory behavioural traits in humans and nonhuman primates, such as social bonding and aggression. The evolution of post-copulatory strategies such as sperm competition and selective abortion may also evolve in the presence of intense competition and these adaptations will also be considered. Although behaviour may not be solely determined by genes, the evidence suggests that the genes discussed in this chapter have some influence on human and nonhuman primate behaviour and that positive selection on these genes results in some degree of population differentiation and diversity.
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Affiliation(s)
- Leslie A Knapp
- Primate Immunogenetics and Molecular Ecology Research Group, Department of Biological Anthropology, University of Cambridge, Cambridge, UK.
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187
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Beigneux E, Féron C, Gouat P. Concordance in mate choice in female mound-building mice. C R Biol 2012; 335:220-5. [PMID: 22464430 DOI: 10.1016/j.crvi.2012.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 01/12/2012] [Accepted: 01/13/2012] [Indexed: 12/01/2022]
Abstract
Females must evaluate male quality to perform mate choice. Since females generally base their selection on different male features, individual females may differ in their choice. In this study, we show that concordance between females in mate choice decisions may arise without any experimental maximization of a particular attractive trait. Choice tests were performed in mound-building mice, Mus spicilegus, a monogamous species. Body odours of two male donors were presented to 12 female subjects individually. To determine female choice, the same pair of males was presented three times to a female. Four different pairs of male body odours were used. Male donors, not related to females, were selected at random in our polymorphic breeding stock. Using this two-way choice design, female mice displayed a clear choice and had a similar preference for particular males.
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Affiliation(s)
- Emilie Beigneux
- laboratoire d'éthologie expérimentale et comparée, université Paris-13, Sorbonne-Paris Cité, Villetaneuse, France.
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188
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Independent evolution of functional MHC class II DRB genes in New World bat species. Immunogenetics 2012; 64:535-47. [PMID: 22426641 DOI: 10.1007/s00251-012-0609-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 02/23/2012] [Indexed: 12/21/2022]
Abstract
Genes of the major histocompatibility complex (MHC) play a pivotal role in the vertebrate immune system and are attractive markers for functional, fitness-related, genetic variation. Although bats (Chiroptera) represent the second largest mammalian order and are prone to various emerging infectious diseases, little is known about MHC evolution in bats. In the present study, we examined expressed MHC class II DRB sequences (exons 1 to 4) of New World bat species, Saccopteryx bilineata, Carollia perspicillata, Noctilio albiventris and Noctilio leporinus (only exon 2). We found a wide range of copy number variation of DRB loci with one locus detected in the genus Noctilio and up to ten functional loci observed in S. bilineata. Sequence variation between alleles of the same taxa was high with evidence for positive selection. We found statistical support for recombination or gene conversion events among sequences within the same but not between bat species. Phylogenetic relationships among DRB alleles provided strong evidence for independent evolution of the functional MHC class II DRB genes in the three investigated species, either by recent gene duplication, or homogenization of duplicated loci by frequent gene conversion events. Phylogenetic analysis of all available chiropteran DRB exon 2 sequences confirmed their monophyletic origin within families, but revealed a possible trans-species mode of evolution pattern in congeneric bat species, e.g. within the genera Noctilio and Myotis. This is the first study investigating phylogenetic relationships of MHC genes within bats and therefore contributes to a better understanding of MHC evolution in one of the most dominant mammalian order.
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189
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Extrapair copulations reduce inbreeding for female red-backed fairy-wrens, Malurus melanocephalus. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.01.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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190
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Cutrera AP, Fanjul MS, Zenuto RR. Females prefer good genes: MHC-associated mate choice in wild and captive tuco-tucos. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.01.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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191
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Whittaker DJ, Dapper AL, Peterson MP, Atwell JW, Ketterson ED. Maintenance of MHC Class IIB diversity in a recently established songbird population. JOURNAL OF AVIAN BIOLOGY 2012; 43:109-118. [PMID: 22685370 PMCID: PMC3368239 DOI: 10.1111/j.1600-048x.2012.05504.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We examined variation at MHC Class IIB genes in a recently established population of dark-eyed juncos (Junco hyemalis) in a coastal urban environment in southern California, USA relative to an ancestral-range population from a nearby species-typical montane environment. The founding population is estimated to have been quite small, but we predicted that variation at the major histocompatibility complex (MHC) among the founders would nevertheless be preserved owing to the high functional significance of MHC. Previous studies of MHC in songbirds have had varying degrees of success in isolating loci, as passerines show extensive MHC gene duplication. In order to compare diversity in the two populations, we employed two published approaches to sequencing MHC Class II exon 2: direct sequencing with exon-based primers, and traditional cloning and sequencing with intron-based primers. Results from both methods show that the colonist population has maintained high levels of variation. Our results also indicate varying numbers of alleles across individuals, corroborating evidence for gene duplication in songbird MHC. While future studies in songbirds may need to take a genomic approach to fully understand the structure of MHC in this lineage, our results show that it is possible to use traditional methods to reveal functional variation across populations.
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Affiliation(s)
- Danielle J. Whittaker
- BEACON Center for the Study of Evolution in Action, Michigan State University, 1441 Biomedical and Physical Sciences, East Lansing, MI, 48824
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Amy L. Dapper
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Mark P. Peterson
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Jonathan W. Atwell
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
| | - Ellen D. Ketterson
- Department of Biology, Indiana University, 1001 East Third St, Bloomington, IN, 47405
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192
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Gilbert OM, Strassmann JE, Queller DC. High relatedness in a social amoeba: the role of kin-discriminatory segregation. Proc Biol Sci 2012; 279:2619-24. [PMID: 22357265 DOI: 10.1098/rspb.2011.2514] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A major challenge for social theory is to explain the importance of kin discrimination for the evolution of altruism. One way to assess the importance of kin discrimination is to test its effects on increasing relatedness within groups. The social amoeba Dictyostelium discoideum aggregates to form a fruiting body composed of dead stalk and live spores. Previous studies of a natural population showed that where D. discoideum occurs in the soil, multiple clones are often found in the same small soil samples. However, actual fruiting bodies usually contain only one clone. We here performed experiments to gauge the effect of kin-discriminatory segregation on increasing relatedness. We mixed co-occurring clones from this population using a relatedness level found in small soil samples. We found a lower proportion of uniclonal fruiting bodies and a lower level of relatedness compared with natural fruiting bodies. We found that the amount of relatedness increase attributable to kin-discriminatory segregation was small. These findings suggest a relatively minor influence of kin-discriminatory segregation on relatedness in D. discoideum. We discuss our results comparing with the results of previous studies, including those of wild clones and laboratory mutants. We ask why wild clones of D. discoideum exhibit a low degree of kin-discriminatory segregation, and what alternative factors might account for high relatedness in D. discoideum.
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Affiliation(s)
- Owen M Gilbert
- Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA.
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193
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Laurent R, Chaix R. MHC-dependent mate choice in humans: why genomic patterns from the HapMap European American dataset support the hypothesis. Bioessays 2012; 34:267-71. [PMID: 22344965 DOI: 10.1002/bies.201100150] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The role of the major histocompatibility complex (MHC) in mate choice in humans is controversial. Nowadays, the availability of genetic variation data at genomic scales allows for a careful assessment of this question. In 2008, Chaix et al. reported evidence for MHC-dependent mate choice among European American spouses from the HapMap 2 dataset. Recently, Derti et al. suggested that this observation was not robust. Furthermore, when Derti et al. applied similar analyses to the HapMap 3 European American samples, they did not see a significant effect. Although some of the points raised by Derti et al. are relevant, we disagree with the reported absence of evidence for MHC-dependent mate choice within the HapMap samples. More precisely, we show here that the MHC dissimilarity among HapMap 3 European American spouses is still extreme in comparison to the rest of the genome, even after multiple testing correction. This finding supports the hypothesis of MHC-dependent mate choice in some human populations.
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Affiliation(s)
- Romain Laurent
- Eco-Anthropologie et Ethnobiologie, UMR 7206 CNRS, MNHN, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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194
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Oliver MK, Piertney SB. Selection maintains MHC diversity through a natural population bottleneck. Mol Biol Evol 2012; 29:1713-20. [PMID: 22323362 DOI: 10.1093/molbev/mss063] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A perceived consequence of a population bottleneck is the erosion of genetic diversity and concomitant reduction in individual fitness and evolutionary potential. Although reduced genetic variation associated with demographic perturbation has been amply demonstrated for neutral molecular markers, the effective management of genetic resources in natural populations is hindered by a lack of understanding of how adaptive genetic variation will respond to population fluctuations, given these are affected by selection as well as drift. Here, we demonstrate that selection counters drift to maintain polymorphism at a major histocompatibility complex (MHC) locus through a population bottleneck in an inbred island population of water voles. Before and after the bottleneck, MHC allele frequencies were close to balancing selection equilibrium but became skewed by drift when the population size was critically low. MHC heterozygosity generally conformed to Hardy-Weinberg expectations except in one generation during the population recovery where there was a significant excess of heterozygous genotypes, which simulations ascribed to strong differential MHC-dependent survival. Low allelic diversity and highly skewed frequency distributions at microsatellite loci indicated potent genetic drift due to a strong founder affect and/or previous population bottlenecks. This study is a real-time examination of the predictions of fundamental evolutionary theory in low genetic diversity situations. The findings highlight that conservation efforts to maintain the genetic health and evolutionary potential of natural populations should consider the genetic basis for fitness-related traits, and how such adaptive genetic diversity will vary in response to both the demographic fluctuations and the effects of selection.
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Affiliation(s)
- Matthew K Oliver
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, United Kingdom.
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195
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Experimental viral evolution to specific host MHC genotypes reveals fitness and virulence trade-offs in alternative MHC types. Proc Natl Acad Sci U S A 2012; 109:3422-7. [PMID: 22323587 DOI: 10.1073/pnas.1112633109] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The unprecedented genetic diversity found at vertebrate MHC (major histocompatibility complex) loci influences susceptibility to most infectious and autoimmune diseases. The evolutionary explanation for how these polymorphisms are maintained has been controversial. One leading explanation, antagonistic coevolution (also known as the Red Queen), postulates a never-ending molecular arms race where pathogens evolve to evade immune recognition by common MHC alleles, which in turn provides a selective advantage to hosts carrying rare MHC alleles. This cyclical process leads to negative frequency-dependent selection and promotes MHC diversity if two conditions are met: (i) pathogen adaptation must produce trade-offs that result in pathogen fitness being higher in familiar (i.e., host MHC genotype adapted to) vs. unfamiliar host MHC genotypes; and (ii) this adaptation must produce correlated patterns of virulence (i.e., disease severity). Here we test these fundamental assumptions using an experimental evolutionary approach (serial passage). We demonstrate rapid adaptation and virulence evolution of a mouse-specific retrovirus to its mammalian host across multiple MHC genotypes. Critically, this adaptive response results in trade-offs (i.e., antagonistic pleiotropy) between host MHC genotypes; both viral fitness and virulence is substantially higher in familiar versus unfamiliar MHC genotypes. These data are unique in experimentally confirming the requisite conditions of the antagonistic coevolution model of MHC evolution and providing quantification of fitness effects for pathogen and host. These data help explain the unprecedented diversity of MHC genes, including how disease-causing alleles are maintained.
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196
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Bahr A, Wilson AB. The evolution of MHC diversity: evidence of intralocus gene conversion and recombination in a single-locus system. Gene 2012; 497:52-7. [PMID: 22301266 DOI: 10.1016/j.gene.2012.01.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Revised: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 11/29/2022]
Abstract
Gene conversion, the unidirectional exchange of genetic material between homologous sequences, is thought to strongly influence patterns of genetic diversity. The high diversity of major histocompatibility complex (MHC) genes in many species is thought to reflect a long history of gene conversion events both within and among loci. Theoretical work suggests that intra- and interlocus gene conversion leave characteristic signatures of nucleotide diversity, but empirical studies of MHC variation have rarely been able to analyze the effects of conversion events in isolation, due to the presence of multiple gene copies in most species. The potbellied seahorse (Hippocampus abdominalis), a species with a single copy of the MH class II beta-chain gene (MHIIb), provides an ideal system in which to explore predictions on the effects of intralocus gene conversion on patterns of genetic diversity. The genetic diversity of the MHIIb peptide binding region (PBR) is high in the seahorse, similar to other vertebrate species. In contrast, the remainder of the gene shows a total absence of synonymous variation and low levels of intronic sequence diversity, concentrated in 3 short repetitive regions and 1-12 SNPs per intron. The distribution of substitutions across the gene results in a patchwork pattern of shared polymorphism between otherwise divergent sequences. The pattern of nucleotide diversity observed in the seahorse MHIIb gene is congruent with theoretical expectations for intralocus gene conversion, indicating that this evolutionary mechanism has played an important role in MHC gene evolution, contributing to both the high diversity in the PBR and the low diversity outside this region. Neutral variation at this locus may be further reduced due to biases in nucleotide composition and functional constraints.
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Affiliation(s)
- Angela Bahr
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
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197
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Hawley DM, Fleischer RC. Contrasting epidemic histories reveal pathogen-mediated balancing selection on class II MHC diversity in a wild songbird. PLoS One 2012; 7:e30222. [PMID: 22291920 PMCID: PMC3264569 DOI: 10.1371/journal.pone.0030222] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 12/14/2011] [Indexed: 11/20/2022] Open
Abstract
The extent to which pathogens maintain the extraordinary polymorphism at vertebrate Major Histocompatibility Complex (MHC) genes via balancing selection has intrigued evolutionary biologists for over half a century, but direct tests remain challenging. Here we examine whether a well-characterized epidemic of Mycoplasmal conjunctivitis resulted in balancing selection on class II MHC in a wild songbird host, the house finch (Carpodacus mexicanus). First, we confirmed the potential for pathogen-mediated balancing selection by experimentally demonstrating that house finches with intermediate to high multi-locus MHC diversity are more resistant to challenge with Mycoplasma gallisepticum. Second, we documented sequence and diversity-based signatures of pathogen-mediated balancing selection at class II MHC in exposed host populations that were absent in unexposed, control populations across an equivalent time period. Multi-locus MHC diversity significantly increased in exposed host populations following the epidemic despite initial compromised diversity levels from a recent introduction bottleneck in the exposed host range. We did not observe equivalent changes in allelic diversity or heterozygosity across eight neutral microsatellite loci, suggesting that the observations reflect selection rather than neutral demographic processes. Our results indicate that a virulent pathogen can exert sufficient balancing selection on class II MHC to rescue compromised levels of genetic variation for host resistance in a recently bottlenecked population. These results provide evidence for Haldane's long-standing hypothesis that pathogens directly contribute to the maintenance of the tremendous levels of genetic variation detected in natural populations of vertebrates.
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Affiliation(s)
- Dana M Hawley
- Center for Conservation and Evolutionary Genetics, Smithsonian Institution, Washington DC, United States of America.
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198
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Bahr A, Sommer S, Mattle B, Wilson AB. Mutual mate choice in the potbellied seahorse (Hippocampus abdominalis). Behav Ecol 2012. [DOI: 10.1093/beheco/ars045] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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199
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Kear PJ, McClure B. How did Flowering Plants Learn to Avoid Blind Date Mistakes? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 738:108-23. [DOI: 10.1007/978-1-4614-1680-7_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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200
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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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