Analysis of Genetic Diversity and Population Structure of Endemic Endangered Goose (Anser cygnoides) Breeds Based on Mitochondrial CYTB.

Simple Summary: The diversity and specificity of the genetic structures of rare and endemic endangered goose (Anser cygnoides) breeds continue to be significant focal points of global concern. In this study, the mitochondrial genome was sequenced from six endemic endangered goose breeds to compare and assess the genetic structures of the rare bird breeds (♂:♀ = 1:1). The research results show that there are 81 haplotypes among the six endemic endangered goose breeds in China. At the same time, a historical dynamic analysis of the migration of endemic endangered goose breeds was conducted. The Wright's fixation index of endemic endangered goose breeds in China is significantly lower than that of European goose breeds. This indicates that the adaptability of endangered breeds in China is relatively low, which can easily affect the long-term survival and reproductive ability of the population. The conservation and exploitation of waterfowl genetic resources leverage the intra- and inter-population variations to enhance the traits relevant to human interests. Hence, there is an urgent need to strategically plan and safeguard the genetic resources of Chinese goose breeds while also devising suitable protection strategies. The analysis of the genetic diversity and historical dynamics of endemic endangered goose breeds structure has attracted great interest. Although various aspects of the goose breed structure have been elucidated, there is still insufficient research on the genetic basis of endemic endangered Chinese goose breeds. In this study, we collected blood samples from Lingxiang White (LX), Yan (YE), Yangjiang (YJ), Wuzong (WZ), Xupu (XP), and Baizi (BZ) geese (Anser cygnoides) and used Sanger sequencing to determine the partial sequence of the cytochrome b (CYTB) gene in a total of 180 geese. A total of 117 polymorphic sites were detected in the 707 bp sequence of the mtDNA CYTB gene after shearing and correction, accounting for approximately 16.55% of the entire sequence. The AT content (51.03%) of the processed sequence was slightly higher than the GC content (48.97%), indicating a preference for purine bases. The YJ, YE, and WZ breeds had the highest population genetic diversity, with a haplotype diversity greater than 0.9 (Hd > 0.9) and average population nucleotide difference of 8.01 (K > 8.01). A total of 81 haplotypes were detected and divided into six major branches. Among the six goose breeds, there were frequent genetic exchanges among LX, YJ, YE, and WZ geese (Nm > 15.00). We analyzed the distribution of base-mismatch differences in goose breeds and tested their historical dynamics for neutrality in Tajima's D and Fu's Fs. For YJ and WZ geese, Tajima's D > 0, but the difference was not significant (p > 0.05). The actual values for the two breeds exhibited multimodal Poisson distributions. The population patterns of the WZ and YJ geese are purportedly relatively stable, and the breeds have not experienced population expansions or bottleneck effects, which is consistent with the neutrality test results. This study provides new insights into the diverse genetic origins and historical dynamics that sustain endemic endangered goose breeds. [ABSTRACT FROM AUTHOR]