臺灣中部山區地景因子對台灣高山田鼠(Microtus kikuchii)和台灣森鼠(Apodemus semotus)族群遺傳結構之影響

The influence of landscape features on population genetic structure of Taiwan vole (Microtus kikuchii) and Formosan mouse (Apodemus semotus) in central Taiwan

李徵葳(Cheng-Wei Lee)

指導教授 ： 林雨德

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.02253

摘要

瞭解地景因子對目標物種的族群遺傳結構之影響，是族群生態學中很重要的一環。地景因子包括目標物種分布範圍內的植被類型、海拔高度、地形變化等，它們會影響棲地品質，進而影響個體的分散狀態和播遷，塑造出族群在空間上的遺傳結構變異。根據傳統的距離隔離效應(isolation by distance, IBD) 理論，族群間的遺傳距離會與地理距離成正相關，然而傳統的「直線距離」(Euclidean distance) 往往缺乏生物意義而與遺傳距離相關性不高；而以地景因子所建構出的「最小成本路徑距離」(least cost distance) 可直觀地提供族群遺傳變異更佳的解釋。本研究以台灣高山田鼠 (Microtus kikuchii)和台灣森鼠(Apodemus semotus)兩種小型哺乳動物為目標物種，探討地景因子對族群遺傳結構的影響。研究地點位於雪山山脈與中央山脈北段的思源啞口及兩側，武陵山區及南湖山區一帶。我在此三個樣區採集兩物種組織，以分析粒線體DNA中的D-loop片段得到各族群間的遺傳距離FST值；再利用地理資訊系統(GIS)建立三種不同的地理距離：直線距離、由地形變化或植被類型建構出的最小成本路徑距離，並與遺傳距離做相關分析。結果顯示，台灣森鼠不具族群遺傳結構，而台灣高山田鼠具高度族群遺傳結構，而其遺傳結構與植被類型有顯著正相關。

關鍵字

族群遺傳結構 ； 地景遺傳學 ； 距離隔離 ； 最小成本模式 ； 台灣高山田鼠 ； 台灣森鼠

並列摘要

Landscape features, including vegetation type, elevation, and topography, can influence the dispersal and distribution of animals, and lead to variation in spatial population genetic structure. According to the isolation-by-distance (IBD) model, the genetic distances among populations can be positively correlated with geographic distances. Recently, researchers have started to use the least-cost-path distance instead of Euclidean distance in examining IBD because of the unrealistic meaning of the latter to organisms. In this thesis, I studied the influences of landscape features on population genetic structure of two rodent species, the Taiwan field vole (Microtus kikuchii) and the Formosan field mouse (Apodemus semotus Thomas) in central Taiwan. Through amplifying the D-loop sequence in mtDNA from animal tissues from 6~8 populations of each species, I computed the genetic distance among populations, the FST value. I calculated the geographic distances under three models: Euclidean distance and two least-cost-path distances based on topography or vegetation type, using geographic information system (GIS). I then analyzed the correlation between genetic distance and the geographic distances conducted from the three models. The results showed that there was no population genetic structure among Apodemus semotus, yet a strong genetic structure was present among Microtus kikuchii populations, and significantly positively correlated with vegetation type.

並列關鍵字

Population genetic structure ； Landscape genetics ； Isolation by distance ； least cost model ； Microtus kikuchii ； Apodemus semotus

參考文獻

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