关键词: 大熊猫, 西氏贝蛔虫, 种群遗传多样性, 线粒体12S, 地理位置多态性, 保护生态学

Abstract: The giant panda is an iconic and threatened species for wildlife conservation in China. Baylisascaris schroederi is the most common intestinal parasite found in the giant panda and represents a significant threat to both wild and captive populations. Given that giant pandas are geographically and genetically distinct and that there often is co-evolution between parasites and hosts, whether the evolution of B. schroederi correlates with the evolution of giant pandas has been, and is still, a matter of controversy. In this study, 34 B. schroederi isolates from two main giant panda populations distributed in Minshan (14) and Qionglai (20) mountain ranges, respectively, were subjected to analysis of population genetic diversities in terms of the complete mitochondrial 12S genes. Results showed that (1) a total of nine haplotypes were detected in the 34 isolates, with high haplotype diversity and low nucleotide diversity; (2) the negative neutrality tests (Tajima’s D and Fu's Fs) and mismatch analysis indicated that B. schroederi experienced a temporary population expansion in the recent past; (3) the low Gst and high Nm values suggested a low genetic variability between Minshan and Qionglai populations; additionally, (4) the phylogenetic tree and network map exhibited a mixed population distribution without area-originated specificity. Collectively, B. schroederi across Minshan and Qionglai exhibited an insignificant genetic differentiation and had low genetic diversities between them. This finding implies different evolutionary rates between B. schroederi and pandas, and the results should contribute to the control of B. schroederi in different mountain-range pandas.

Key words: Baylisascaris schroederi, Conservation ecology, Genetic diversity, Giant pandas, Mitochondrial 12S, Phylogeography