Data from: Historical species distribution models predict species limits in western Plethodon salamanders

Allopatry is commonly used to predict boundaries in species delimitation investigations under the assumption that currently allopatric distributions are indicative of reproductive isolation; however, species ranges are known to change over time. Incorporating a temporal perspective of geographic distributions should improve species delimitation; to explore this, we investigate three species of western Plethodon salamanders that have shifted their ranges since the end of the Pleistocene. We generate species distribution models (SDM) of the current range, hindcast these models onto a climatic model 21 Ka, and use three molecular approaches to delimit species in an integrated fashion. In contrast to expectations based on the current distribution, we detect no independent lineages in species with allopatric and patchy distributions (Plethodon vandykei and Plethodon larselli). The SDMs indicate that probable habitat is more expansive than their current range, especially during the last glacial maximum (LGM) (21 Ka). However, with a contiguous distribution, two independent lineages were detected in Plethodon idahoensis, possibly due to isolation in multiple glacial refugia. Results indicate that historical SDMs are a better predictor of species boundaries than current distributions, and strongly imply that researchers should incorporate SDM and hindcasting into their investigations and the development of species hypotheses.异域分布（Allopatry）常被应用于物种界定研究的边界预测，其核心假设为当前呈异域分布的类群可作为生殖隔离的指征；但学界已证实物种分布范围会随时间动态变化。纳入地理分布的时间维度视角，有望优化物种界定工作。为探究这一议题，我们针对更新世末期以来分布范围发生变迁的3种西部无肺螈属（Plethodon）蝾螈展开研究：我们构建了当前分布范围的物种分布模型（Species Distribution Model, SDM），并将这些模型回溯至21 Ka的古气候场景中进行模拟；同时采用3种分子方法，以整合框架开展物种界定。与基于当前分布的预期结果相悖，我们在呈异域且斑块状分布的凡氏无肺螈（Plethodon vandykei）与拉氏无肺螈（Plethodon larselli）中未检测到独立演化支。物种分布模型结果显示，其潜在适宜栖息地范围较当前分布更为广阔，尤以末次盛冰期（Last Glacial Maximum, LGM，即21 Ka）时期为甚。而在呈连续分布的爱达荷无肺螈（Plethodon idahoensis）中则检测到2个独立演化支，这一现象可能与该类群曾在多个冰期避难所发生隔离有关。研究结果表明，基于历史物种分布模型的物种边界预测效果优于当前分布数据，且强烈提示研究者应将物种分布模型与回溯模拟方法纳入其研究工作及物种假说的构建流程。