臺灣兩種共域石龍子的水分散失與棲地利用關係之探討

Abstract

物種生存直接受到可利用棲地的影響，而棲地的尺度又可分為大尺度與小尺度。本研究分別以大尺度與小尺度的角度調查臺灣中部麗紋石龍子與印度蜓蜥的分布狀況，並參考過去文獻預測兩個共域物種的微棲地尺度可能會有分化。研究調查的量化資料，顯示了麗紋石龍子傾向利用開闊，且高溫與乾燥的微環境；而印度蜓蜥則傾向利用較遮蔽度高，且低溫潮濕的環境。進一步比較兩個物種幼體、亞成體與雌雄之間水分散失量的差異，結果顯示出兩個物種的幼體保水能力都較差，而對照野外穿越線調查，兩物種的幼體也很少被肉眼記錄到，顯示幼體分布在相對隱蔽的環境中。比較兩個物種，印度蜓蜥的保水能力皆顯著較差，因此傾向分布在閉鬱低溫的潮濕環境。分析兩個物種所利用的微環境資料，顯示出兩個物種的環境溼度有明顯的區隔，但分布溫度仍有某程度的重疊。因此本研究推測，印度蜓蜥可能由於受到水分生理的限制，分布在高濕低溫的微環境；而麗紋石龍子則因為有較好的保水能力，加上本身在溫度生理上對於高溫的偏好，而傾向分布在開闊高溫且乾燥的環境中。但兩個物種的棲地分化是否也同時受到的影響，則需要進一步的操做性實驗來驗證。We study the habitat use of two sympatric skinks Eumeces elegans and Sphenomorphus indicus in central Taiwan. The environment data in wild was collection at two different scales: large habitat scales and microhabitat scales. The quantified results at these different spatial scales showed these two species select different environment. E. elegans occupied microhabitats with fewer trees, higher ambient temperature, and low humidity; whereas, S. indicus occupied microhabitats with more cover, lower ambient temperature, and high humidity. We also measured the evaporative water loss of these two skinks. Results indicated that the juveniles of both two skinks were loss more water through evaporationthan subadults or adults. On the other hand, S. indicus loss more water than E. elegans in either juveniles, subadults and adults. Comparisons of water loss data with wild investigation, we found that the juveniles of these two skinks were difficult to find in wild. Therefore, juveniles may be restricted to high covered microhabitat. Moreover, microenvironment data predict that S. indicus may be physiologically restricted to moist habitats; and E. elegans were prefer to use dry and high temperature site because its higher thermal requirements. However, the microhabitat partitioning of these two skinks may also a consequence of interaction in each other. Further operational experiment should be test.