The influence of history, geography and environment on patterns of diversification in the western terrestrial garter snake

Aim: A central aim of biogeography is to understand how biodiversity is generated and maintained across landscapes. Here, we establish phylogenetic and population genetic patterns in a widespread reptile to quantify the influence of historical biogeography and current environmental variation on patterns of genetic diversity.
Location: Western North America.
Taxon: Western terrestrial garter snake, Thamnophis elegans.
Methods: We used double-digest RADseq to estimate phylogenetic relationships and characterize population genetic structure across the three widespread subspecies of T. elegans: T. e. vagrans (wandering garter snake), T. e. elegans (mountain garter snake) and T. e. terrestris (coast garter snake). We assessed patterns of dispersal and vicariance across biogeographic regions using ancestral area reconstruction (AAR) and deviations from isolation-by-distance across the landscape using estimated effective migration surfaces (EEMS). We identified environmental variables potentia...

目标：生物地理学的核心目标之一是理解生物多样性如何在景观中产生和维持。本研究通过解析一种广布爬行动物的系统发育与种群遗传模式，量化历史生物地理学及当前环境变异对遗传多样性格局的影响。
分布区域：北美西部。
分类单元：西部陆栖束带蛇（Thamnophis elegans）。
方法：我们采用双酶切RAD测序（double-digest RADseq）技术，评估了T. elegans三个广布亚种的系统发育关系并刻画其种群遗传结构，包括漫游束带蛇（T. e. vagrans）、山地束带蛇（T. e. elegans）及海岸束带蛇（T. e. terrestris）。通过祖先区域重建（AAR）分析生物地理区域间的扩散与隔离模式，并利用估计有效迁移表面（EEMS）探究景观中偏离距离隔离的现象。