Data from: Cryptic elevational zonation in trapdoor spiders (Araneae, Antrodiaetidae, Aliatypus janus complex) from the California southern Sierra Nevada

The relative roles of ecological niche conservatism versus niche divergence in promoting montane speciation remains an important topic in biogeography. Here, our aim was to test whether lineage diversification in a species complex of trapdoor spiders corresponds with riverine barriers or with an ecological gradient associated with elevational tiering. Aliatypus janus was sampled from throughout its range, with emphasis on populations in the southern Sierra Nevada Mountains of California. We collected multi-locus genetic data to generate a species tree for A. janus and its close relatives. Coalescent based hypothesis tests were conducted to determine if genetic breaks within A. janus conform to riverine barriers. Ecological niche models (ENM) under current and Last Glacial Maximum (LGM) conditions were generated and hypothesis tests of niche conservatism and divergence were performed. Coalescent analyses reveal deeply divergent genetic lineages within A. janus, likely corresponding to cryptic species. Two primary lineages meet along an elevational gradient on the western slopes of the southern Sierra Nevada Mountains. ENMs under both current and LGM conditions indicate that these groups occupy largely non-overlapping niches. ENM hypothesis testing rejected niche identity between the two groups, and supported a sharp ecological gradient occurring where the groups meet. However, the niche similarity test indicated that the two groups may not inhabit different niches from their backgrounds. The Sierra Nevada Mountains provide a natural laboratory for simultaneously testing ecological niche divergence and conservatism and their role in speciation across a diverse range of taxa. Aliatypus janus represents a species complex with cryptic lineages that may have diverged due to parapatric speciation along an ecological gradient, or been maintained by the evolution of ecological niche differences following allopatric speciation.生态位保守性（ecological niche conservatism）与生态位分化（niche divergence）在推动山地物种形成（montane speciation）中的相对作用，始终是生物地理学（biogeography）领域的重要研究议题。本研究旨在检验陷阱蛛（trapdoor spiders）物种复合群（species complex）的谱系分化，究竟与河流屏障（riverine barriers）相关，还是与海拔分层（elevational tiering）相关的生态梯度有关。我们对陷阱蛛属物种Aliatypus janus的整个分布范围进行了采样，重点关注美国加利福尼亚州内华达山脉南部的种群。本研究收集了多位点遗传数据，以构建A. janus及其近缘类群的物种树（species tree）。开展了基于溯祖（coalescent）的假设检验，以明确A. janus内部的遗传断裂（genetic breaks）是否符合河流屏障假说。我们构建了当前气候与末次盛冰期（Last Glacial Maximum, LGM）条件下的生态位模型（Ecological niche models, ENM），并针对生态位保守性与分化开展了假设检验。溯祖分析结果显示，A. janus内部存在深度分化的遗传谱系，这些谱系大概率对应隐存物种（cryptic species）。两支主要遗传谱系在内华达山脉南部西坡的海拔梯度上交汇。当前及末次盛冰期的生态位模型均表明，这两个类群的生态位基本不存在重叠。生态位模型的假设检验拒绝了两类群间的生态位同一性（niche identity）假说，并支持在两类群交汇区域存在显著的生态梯度。然而，生态位相似性检验（niche similarity test）结果显示，两类群与其所处背景环境的生态位未必存在显著差异。内华达山脉为同时检验生态位分化与保守性，以及二者在多样类群的物种形成过程中所发挥的作用，提供了天然实验室。Aliatypus janus代表了一个携带隐存谱系的物种复合群，这些隐存谱系可能通过沿生态梯度的邻域物种形成（parapatric speciation）而发生分化，或是在异域物种形成（allopatric speciation）后，经由生态位差异的演化得以维持。