氣候及地理因子與不同海拔楓屬植物族群空間遺傳組成之關係

Abstract

物種的分布及遺傳結構可能反應環境差異，氣候變化可能造成族群分歧，而地理距離亦可能影響其遺傳結構。為探討區域環境差異及地理因子與其遺傳結構的關聯性，本研究利用台灣楓屬植物尖葉楓 (Acer caudatifolium)及紅榨楓 (A. rubescens)其廣泛分布以及海拔分布差異的特性，使用17組微衛星標記計算遺傳變異程度，並將遺傳結構與每一個體的經緯度、海拔及氣候變因進行相關性分析。根據Analysis of molecular variance (AMOVA)結果可知尖葉楓及紅榨楓具明顯遺傳分化，也支持STRUCTURE的歸群。由Redundancy analysis (RDA)結果可知尖葉楓和紅榨楓的個體遺傳變異與氣候及地理因子呈現相關，顯示氣候及空間效應可能支配兩物種的遺傳分布。此外地理因子與低海拔尖葉楓個體遺傳分布的相關性更為顯著，表示山脈的隔離效應對低海拔物種的基因交流的阻隔更為明顯。因此本研究推論氣候和地理因子對不同海拔分布物種的遺傳變異產生不同影響壓力，也反應近緣樹種因環境差異而維持其基礎生態棲位及遺傳分化。

Climate change and geographical distribution may affect population divergence and genetic structure of the species. To explore the effect of regional environmental differences on genetic structure, this study used the wide distribution and elevation difference of Acer caudatifolium and A. rubescens as material. This study used 17 microsatellites to detect climatic and geographic factors to correlate with genetic variation and to assess the genetic structure. The AMOVA showed the significant genetic differentiation between the two species in microsatellites, and also supported the assignment results. The results of RDA revealed that the individual genetic variation of the two species was related to the climate and geographical factors which revealed that the climatic and spatial effects may dominate the genetic distribution of the two species. In addition, the correlation between geographical factors and the genetic distribution of A. caudatifolium was more significant that indicated the isolation effect of physical barrier of mountain ranges on the gene flow among populations of low-elevational species. Therefore, this study inferred the climatic and geographical factors may produce different pressures on genetic variation of species at different elevations, which reflected the key rule of environmental heterogeneity on the maintenance of fundamental niches and genetic differentiation between closely related species.