Population genetic diversity and geographical differentiation of MHC class II DAB genes in the vulnerable Chinese egret (Egretta eulophotes)
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Major histocompatibility complex (MHC) genes are excellent markers for the study of adaptive genetic variation occurring over different geographical scales. The Chinese egret (Egretta eulophotes) is a vulnerable ardeid species with an estimated global population of 2600–3400 individuals. In this study, we sampled 172 individuals of this egret (approximately 6 % of the global population) from five natural populations that span the entire distribution range of this species in China. We examined their population genetic diversity and geographical differentiation at three MHC class II DAB genes by identifying eight exon 2 alleles at Egeu-DAB1, eight at Egeu-DAB2 and four at Egeu-DAB3. Allelic distributions at each of these three Egeu-DAB loci varied substantially within the five populations, while levels of genetic diversity varied slightly among the populations. Analysis of molecular variance showed low but significant genetic differentiation among five populations at all three Egeu-DAB loci (haplotype-based ϕST: 0.029, 0.020 and 0.042; and distance-based ϕST: 0.036, 0.027 and 0.043, respectively; all P < 0.01). The Mantel test suggested that this significant population genetic differentiation was likely due to an isolation-by-distance pattern of MHC evolution. However, the phylogenetic analyses and the Bayesian clustering analysis based on the three Egeu-DAB loci indicated that there was little geographical structuring of the genetic differentiation among five populations. These results provide fundamental population information for the conservation genetics of the vulnerable Chinese egret.
KeywordsGenetic diversity Population differentiation Geographical variation MHC Threatened species
We thank Yufei Dai who helped collect some samples for this study. This work was funded by the National Natural Science Foundation of China (Grant Nos. 41476113 and 31272333) and by the Fujian Natural Science Foundation of China (2010Y2007).
Compliance with ethical standards
Conflict of interest
We declare that we have no conflict of interests.
All procedures involving collection of animal tissue in the wild were approved by the Administration Center for Wildlife Conservation in Fujian Province (FJWCA-1208) and were in accordance with its ethical standards.
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