Despite the importance of the geographical arrangement of populations for the inference of species boundaries, only a few approaches that integrate spatial information into species delimitation have thus far been developed. Persistent differentiation of sympatric groups of individuals is the best criterion for species status. Species delimitation becomes more prone to error if allopatric metapopulations are considered because it is often difficult to assess whether observed differences between allopatric metapopulations would be sufficient to prevent the fusion of these metapopulations upon contact. We propose a novel approach for testing the hypothesis that the multilocus genetic distances between individuals or populations belonging to two different candidate species are not larger than expected based on their geographical distances and the relationship of genetic and geographical distances within the candidate species. A rejection of this null hypothesis is an argument for classifying the two studied candidate species as distinct species. Case studies show that the proposed tests are suitable to distinguish between intra‐ and interspecific differentiation. The regression approach proposed here is more appropriate for testing species hypotheses with regard to isolation by distance than (partial) Mantel tests. Our tests assume a linear relationship between genetic and (transformed) geographical distances. This assumption can be compromised by a high genetic variability within populations as found in a case study with microsatellite markers.

中文翻译：

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物种划界和地理。

尽管人口地理布局对于推断物种边界很重要，但迄今为止，仅开发了几种将空间信息整合到物种定界中的方法。个体同胞群体的持续分化是物种地位的最佳标准。如果考虑到异源性种群，物种定界变得更容易出错，因为通常很难评估所观察到的异源性种群之间的差异是否足以阻止这些亚种群在接触时融合。我们提出了一种新颖的方法来检验以下假设：根据两个候选物种的地理距离以及候选物种内遗传距离与地理距离的关系，属于两个不同候选物种的个体或种群之间的多位点遗传距离不大于预期。否定这个零假设是将两个研究的候选物种分类为不同物种的论点。案例研究表明，提出的测试适合区分种内和种间分化。与（部分）Mantel检验相比，此处提出的回归方法更适合于测试关于距离隔离的物种假设。我们的测试假设遗传距离与（转换的）地理距离之间存在线性关系。