Divergent patterns of selection on the DAB and DXB MHC class II loci in Xiphophorus fishes

Summers, Kyle; Roney, Kelly E.; Silva, Jack da; Capraro, Gerald A.; Cuthbertson, Brandon J.; Kazianis, Steven; Rosenthal, Gil G.; Ryan, Michael J.; McConnell, Thomas J.

doi:10.1007/s10709-008-9284-4

Cited by 8 publications

(6 citation statements)

References 60 publications

(62 reference statements)

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“…We obtained species occurrence data for all Xiphophorus species from the Fishnet2 Portal ( http://fishnet2.net ), the literature [ 59 , 60 , 81 – 86 ], and field collections in Mexico and Honduras conducted by the authors. All occurrence records were vetted against the literature to ensure that occurrences for each species fell within their documented, native distributions [ 59 , 60 ], and non-native records were removed from the dataset.…”

Section: Methodsmentioning

confidence: 99%

Ecological divergence and conservatism: spatiotemporal patterns of niche evolution in a genus of livebearing fishes (Poeciliidae: Xiphophorus)

Culumber

Tobler

2016

BMC Evol Biol

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BackgroundEcological factors often have a strong impact on spatiotemporal patterns of biodiversity. The integration of spatial ecology and phylogenetics allows for rigorous tests of whether speciation is associated with niche conservatism (constraints on ecological divergence) or niche divergence. We address this question in a genus of livebearing fishes for which the role of sexual selection in speciation has long been studied, but in which the potential role of ecological divergence during speciation has not been tested.ResultsBy combining reconstruction of ancestral climate tolerances and disparity indices, we show that the earliest evolutionary split in Xiphophorus was associated with significant divergence for temperature variables. Niche evolution and present day niches were most closely associated with each species’ geographic distribution relative to a biogeographic barrier, the Trans-Mexican Volcanic Belt. Tests for similarity of the environmental backgrounds of closely related species suggested that the relative importance of niche conservatism and divergence during speciation varied among the primary clades of Xiphophorus. Closely related species in the two swordtail clades exhibited higher levels of niche overlap than expected given environmental background similarity indicative of niche conservatism. In contrast, almost all species of platyfish had significantly divergent niches compared to environmental backgrounds, which is indicative of niche divergence.ConclusionThe results suggest that the relative importance of niche conservatism and divergence differed among the clades of Xiphophorus and that traits associated with niche evolution may be more evolutionarily labile in the platyfishes. Our results ultimately suggest that the taxonomic scale of tests for conservatism and divergence could greatly influence inferences of their relative importance in the speciation process.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0593-4) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 99%

Ecological divergence and conservatism: spatiotemporal patterns of niche evolution in a genus of livebearing fishes (Poeciliidae: Xiphophorus)

Culumber

Tobler

2016

BMC Evol Biol

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“…For the authors, the nucleotide divergence of DXB compared with DAB (McConnell et al , 1998 b ), and the alternative splicing of DXB, suggest that in Xiphophorus species, DXB may have a different role in the processing and presentation of peptides than the classical type DAB gene. Recent work investigating the sequence information of those transcripts demonstrated the presence of weak positive selection acting on DXB (Summers et al , 2009). As it is known that the signature of positive selection can persist for a very long time (Garrigan & Hedrick, 2003), it is possible that the signature detected in Xiphophorus spp.…”

Section: The Potential Of Mhc Genes For Local Adaptationmentioning

confidence: 99%

Major histocompatibility complex polymorphism: dynamics and consequences of parasite‐mediated local adaptation in fishes

Eizaguirre

Lenz

2010

Journal of Fish Biology

100

114

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Parasitism is a common form of life and represents a strong selective pressure for host organisms. In response to this evolutionary pressure, vertebrates have developed genetically coded defences such as the major histocompatibility complex (MHC). Mechanisms of parasite-mediated selection not only maintain outstanding polymorphism in these genes but have also been proposed to further promote host population divergence and ultimately speciation because it can drive evolution of local adaptation in which MHC genes play a crucial role. This review first highlights the dynamics and complexity of parasite-mediated selection in natural systems, which not only depends on dominating parasite strategies and on the taxonomic diversity of the parasite community but also includes the differences in parasite communities between habitats and niches, creating divergent selection on locally adapted populations. Then the different ways in which MHC genes potentially allow vertebrates to respond to these dynamics and to adapt locally are outlined. Finally, it is proposed that varying selection strength in time and space may lead to variation in the strength of precopulatory reproductive isolation which has evolved to maintain local adaptation.

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“…The identified sequences at the MHC locus were checked for homology against Xiphophorus fishes (Summers et al, 2009). �ew alleles were nominated according to accepted nomenclature rules (�avies et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

Genetic variation and balancing selection at MHC class II exon 2 in cultured stocks and wild populations of orange-spotted grouper (Epinephelus coioides)

Meng¹,

Yang²,

Fan³

et al. 2012

Genet. Mol. Res.

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ABSTRACT. Major histocompatibility complex (MHC) molecules play vital roles in triggering adaptive immune responses and are considered the most variable molecules in vertebrates. Recently, many studies have focused on the polymorphism and evolution mode of MHC in both model and non-model organisms. Here, we analyzed the MHC class II exon 2-encoding β chain in comparison with the mitochondrial Cytb gene and our previously published microsatellite data set in three cultured stocks and four wild populations of the orange-spotted grouper (Epinephelus coioides) in order to investigate its genetic variation and mechanism of evolution. We detected one to four alleles in one individual, suggesting that at least two loci exist in the orange-spotted grouper, as well as a particularly high level of allelic diversity at the MHC loci. Furthermore, the cultured stocks exhibited reduced allelic diversity compared to the wild counterparts. We found evidence of balancing selection at MHC class II exon 2, and codon sites under positive selection were largely correspondent to the proteinbinding region. In addition, MHC class II exon 2 revealed significant differences between population differentiation patterns from the neutral mitochondrial Cytb and microsatellites, which may indicate local adaptation at MHC loci in orange-spotted grouper originating from the South China Sea and Southeast Asia.

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Divergent patterns of selection on the DAB and DXB MHC class II loci in Xiphophorus fishes

Cited by 8 publications

References 60 publications

Ecological divergence and conservatism: spatiotemporal patterns of niche evolution in a genus of livebearing fishes (Poeciliidae: Xiphophorus)

Ecological divergence and conservatism: spatiotemporal patterns of niche evolution in a genus of livebearing fishes (Poeciliidae: Xiphophorus)

Major histocompatibility complex polymorphism: dynamics and consequences of parasite‐mediated local adaptation in fishes

Genetic variation and balancing selection at MHC class II exon 2 in cultured stocks and wild populations of orange-spotted grouper (Epinephelus coioides)

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