利用粒線體與微衛星分子標記分析臺灣石虎族群遺傳結構

Abstract

石虎（Prionailurus bengalensis）為貓科豹貓屬物種，廣泛分布於亞洲地區，是臺灣僅有的兩種原生貓科動物之一。文獻指出島嶼型的石虎亞種多面臨遺傳變異性低與族群滅絕的風險，然臺灣缺乏相關的遺傳研究。是以本研究分析臺灣石虎粒線體分子標記多樣性與親緣關係，並篩選適用的微衛星分子標記，以檢視臺灣石虎族群的遺傳特性，並建構遺傳分析之基礎。分析68個石虎樣本之粒線體分子標記，發現臺灣石虎族群的粒線體遺傳多樣性偏低（細胞色素b/D-loop單套型歧異度為0.378/0.428；核苷酸歧異度為0.03% /0.12%）。細胞色素b/D-loop單套型有兩個遺傳分群，與地理分布無明顯相關，其中苗栗之遺傳多樣性高於南投。利用中性檢測、核苷酸變異分布與貝氏天際線圖檢視臺灣石虎族群歷史變動，發現距今5,000年前以前的石虎族群大小穩定，其後則有微幅的族群擴張。分析亞種的親緣關係樹（鄰接、最大似然及貝氏）與特徵序列，發現臺灣石虎的所有單套型形成獨立遺傳支系。此外本研究經由跨物種微衛星基因座測試以72%成功率篩選出13組在臺灣石虎族群具有多型性之微衛星基因座，未來若能測試其個體鑑別能力，或可做為有效評估近代演化事件的遺傳分析工具。本研究釐清臺灣石虎族群之遺傳多樣性組成，可做為保育策略擬定與族群遺傳監測之參考。

Leopard cat （Prionailurus bengalensis） is widely distributed in Asia, and it is a rare species protected by the Wildlife Conservation Law in Taiwan. Many studies have stated that island populations are at the risks of low genetic diversity and extinction. To understand the genetic status of leopard cat populations in Taiwan, this study tried to construct the techniques of genetic analysis. Sixty-eight samples were obtained to analyze mitochondrial DNA markers. The low values of haplotype diversity (H=0.378/0.425 in cytb/D-loop) and nucleotide diversity (π=0.03%/0.12% in cytb/D-loop) revealed that population bottleneck effect may have occurred recently. The leopard cat populations in Taiwan lack geography structure; as a result, the populations with relatively high genetic diversity, like Miaoli and Nantou, should be regarded as key groups to protect. The historical demography of leopard cat populations in Taiwan inferred from the neutrality test, mismatch distribution and Bayesian skyline plot indicated a stable population in the past, but slightly expanded since 5,000 years before present. The subspecies phylogenetic tree divided the populations of leopard cats into two clades. And the leopard cat populations in Taiwan form an independent genetic cluster. Results of this study help to clarify the genetic diversity of leopard cat populations in Taiwan, and served as a fundamental data to leopard cat conservation. For a better explanation of evolutionary history of leopard cats, we should collect more samples from each county and China. Additionally, we successfully selected 13 microsatellite loci with polymorphism, which can be regarded as an effective genetic analysis tool.