Low Genetic Diversity and Low Gene Flow Corresponded to a Weak Genetic Structure of Ruddy-Breasted Crake (Porzana fusca) in China

Genetic diversity of toll-like receptor genes in the vulnerable Chinese egret (Egretta eulophotes)

Toll-like receptor (TLR) genes have recently been employed to assess genetic diversity, as they can be used to infer both demographic history and adaptation to environments with different pathogen pressure. Here, we sampled 120 individuals of the Chinese egret (Egretta eulophotes), a globally vulnerable species, from four breeding populations across China. We assessed the levels of genetic diversity, selection pressure, and population differentiation at seven TLR loci (TLR1LB, TLR2A, TLR3, TLR4, TLR5, TLR7, and TLR15). Using a variety of metrics (SNPs, heterozygosity, nucleotides, haplotypes), our analyses showed that genetic diversity was lower at 4 of the 7 TLR loci in the vulnerable Chinese egret compared to the more common little egret (Egretta garzetta). The selection test indicated TLRs, except for TLR5, were under purifying selection in TLR evolution, suggesting that low TLR genetic diversity in the Chinese egret may be caused by purifying selection. Moreover, analysis of molecular variance indicated low but significant population differentiation among four populations at all of the TLR loci in this egret. However, some comparisons based on fixation index analyses did not show significant population differentiation, and Bayesian clustering showed admixture. Our finding suggested that these four populations of the Chinese egret in China may be considered a single unit for conservation planning. These results, the new report of TLR genetic diversity in a long-distance migratory vulnerable Ardeid species, will provide fundamental TLR information for further studies on the conservation genetics of the Chinese egret and other Ardeids.

Bi-parentally Inherited Genetic Evidence for Male-Biased Dispersal in Common Moorhen (Gallinula chloropus)

Dispersal is a life history trait that has relevant effect on both the dynamics and the genetics of species and sex-biased dispersal depends on how resource competition affects each of the sexes. In this study, a total of 210 blood samples including 121 Common Moorhen (Gallinula chloropus) females and 89 males were collected from 18 diverse areas during the breeding season. Based on 8 microsatellite markers analyses, we found that the most genetic diversities from female populations were higher than those from the males, where only 2 male individuals were identified as the long-distance dispersal. Analyses of sex-biased dispersal conducted over all sampling sites indicated that m_AI (female m_AI = 0.195, male m_AI = - 0.265, P = 0.01), F_ST (female F_ST = 0.045, male F_ST = 0.026, P = 0.020), and r (female r = 0.118, male r = 0.064, P = 0.010) in females were all significantly higher than those in males at the 0.05 level, which suggested a male-biased dispersal pattern in this species. Our Mantel test results suggested a significant isolation-by-distance pattern for females but not for males, which corresponded to the more frequent dispersal and gene flow in males than in females. This dispersal pattern could be explained by the special life history trait and mating system that Common Moorhen pair formation occurs before they leave the flock in the spring to establish territories and its females initiate courtship more frequently than males and compete with each other to pair with small males with large fat reserves. The philopatric female could benefit most from knowledge of a particular area because they may win more intrasexual competitions in the breeding season and be able to produce more offspring if they are familiar with the local resources.