Data from: Isolation-by-distance in landscapes: considerations for landscape genetics

In landscape genetics, isolation-by-distance (IBD) is regarded as a baseline pattern that is obtained without additional effects of landscape elements on gene flow. However, the configuration of suitable habitat patches determines deme topology, which in turn should affect rates of gene flow. IBD patterns can be characterized either by monotonically increasing pairwise genetic differentiation (for example, FST) with increasing interdeme geographic distance (case-I pattern) or by monotonically increasing pairwise genetic differentiation up to a certain geographical distance beyond which no correlation is detectable anymore (case-IV pattern). We investigated if landscape configuration influenced the rate at which a case-IV pattern changed to a case-I pattern. We also determined at what interdeme distance the highest correlation was measured between genetic differentiation and geographic distance and whether this distance corresponded to the maximum migration distance. We set up a population genetic simulation study and assessed the development of IBD patterns for several habitat configurations and maximum migration distances. We show that the rate and likelihood of the transition of case-IV to case-I FST–distance relationships was strongly influenced by habitat configuration and maximum migration distance. We also found that the maximum correlation between genetic differentiation and geographic distance was not related to the maximum migration distance and was measured across all deme pairs in a case-I pattern and, for a case-IV pattern, at the distance where the FST–distance curve flattens out. We argue that in landscape genetics, separate analyses should be performed to either assess IBD or the landscape effects on gene flow.在景观遗传学中，距离隔离（isolation-by-distance, IBD）被视作未受景观要素对基因流额外影响的基准格局。然而，适宜生境斑块的空间配置决定了局域种群（deme）的拓扑结构，进而对基因流速率产生影响。距离隔离格局可分为两类：其一为成对遗传分化（例如FST）随局域种群间地理距离增加呈单调递增趋势（模式I）；其二为成对遗传分化随地理距离增加单调递增至某一临界距离，此后便不再呈现可检测的相关性（模式IV）。本研究旨在探究景观配置是否会影响模式IV向模式I转变的速率，同时明确遗传分化与地理距离间最高相关系数所对应的局域种群间距，以及该间距是否与最大迁移距离相符。我们开展了种群遗传模拟研究，评估了多种生境配置与最大迁移距离下距离隔离格局的演化过程。研究结果表明，模式IV向模式I的FST-距离关系转变的速率与可能性，显著受生境配置与最大迁移距离的影响。此外我们发现，遗传分化与地理距离间的最高相关系数并不与最大迁移距离相关：在模式I格局中，该相关系数存在于所有局域种群对之间；而在模式IV格局中，该相关系数出现在FST-距离曲线趋于平缓的临界距离处。我们认为，在景观遗传学研究中，应分别开展距离隔离评估与景观要素对基因流影响的分析。