Population differentiation at a regional scale in spadefoot toads： contributions of distance and divergent selective environments

作     者：Amber M. RICE Michael A. MCQUILLAN Heidi A. SEEARS Joanna A. WARREN 

作者机构：Department of Biological Sciences Lehigh University BethLehem PA 18015 USA 

出 版 物：《Current Zoology》 (动物学报（英文版）)

年 卷 期：2016年第62卷第2期

页      面：193-206页

核心收录：

学科分类：07[理学] 09[农学] 0904[农学-植物保护] 090401[农学-植物病理学] 090402[农学-农业昆虫与害虫防治] 0701[理学-数学] 070101[理学-基础数学] 

基　　金：funded by Lehigh University 

主　　题：cascade reinforcement character displacement reproductive isolation spatial scale Spea multipficata speciation 

摘      要：The causes of population differentiation can provide insight into the origins of early barriers to gene flow. Two key drivers of population differentiation are geographic distance and local adaptation to divergent selective environments. When reproductive isolation arises because some populations of a species are under selection to avoid hybridization while others are not, population differentiation and even speciation can result. Spadefoot toad populations Spea multiplicata that are sympatric with a congener have undergone reinforcement. This reinforcement has resulted not only in increased reproductive isolation from the congener, but also in the evolution of reproductive isolation from nearby and distant conspecific allopatric populations. We used multiple approaches to evaluate the contributions of geographic distance and divergent selective environments to population structure across this regional scale in S. multiplicata, based on genotypes from six nuclear microsatellite markers. We compared groups of populations varying in both geographic location and in the presence of a congener. Hierarchical F-statistics and results from cluster analyses and discriminant analyses of principal components all indicate that geographic distance is the stronger contributor to genetic differentiation among S. multiplicata populations at a regional scale. However, we found evidence that adaptation to divergent selective environments also contributes to population structure. Our findings highlight how variation in the balance of evolutionary forces acting across a species＇ range can lead to variation in the relative contributions of geographic distance and local adaptation to population differentiation across different spatial scales.