從型態功能學探討台北盆地兩種攀木蜥蜴的共域機制

Abstract

斯文豪氏攀蜥(Japalura swinhonis)與黃口攀蜥(Japalura polygonata xanthostoma)兩物種的地理分佈範圍在台灣北部地區重疊，在大部份地區只有單一物種族群，但有少數地區為兩物種共存。為了解釋兩物種如何可以共存，探討共域和非共域地區族群型值是否具有差異(型值置換假說的先決條件)。野外結果部份，我們發現共域和非共域地區族群，在頭型(頭高)上具有差異。而在實驗室內試驗結果發現，頭型相對大小會影響咬合力大小，而咬合力大小是打鬥能力的重要指標，而且頭型大小也會影響到在不同尺寸棲木上的奔跑速度。雄性斯文豪氏攀蜥頭型較大，當其與黃口攀蜥競爭棲木資源時，雖然打鬥能力較強，但是黃口攀蜥棲木移動能力較強，因此兩物種間可能存在打鬥能力和移動能力間的取捨，造成這兩個物種可以共存。

The geographic distributions of Japalura swinhonis and Japalura polygonata xanthostoma overlap in northern Taiwan. Two species coexist in some locations, but not others. I investigated whether differences in morphology (standardized for overall sizes) occurred between sympatric and allopatric populations (a precondition for character displacement). I found morphological differences in head height and head dimensions in the field. In the laboratory test, I found head dimension can affect bite force and fighting ability, and it can affect sprint ability on different size of perch. When the two species competed for perch resource, male Japalura swinhonis had greater head size and bite force, but they suffered greater reduction in sprint ability than Japalura polygonata xanthostoma as perch incline change. It suggested a trade-off existed between fighting and motion ability in the two species, therefore they could coexist in some locations.