During the historical building of a species range, individual colonizers have to confront different ecological challenges, and the capacity of the species to broaden its range may depend on the total amount of adaptive genetic variation supplied by evolution. We set out to increase our understanding of what defines a range and the role of underlying genetics by trying to predict an entire species’ range from the geographical distribution of its genetic diversity under selection. We sampled five populations of the western Mediterranean lizard Psammodromus algirus that inhabit a noticeable environmental gradient of temperature and precipitation. We correlated the genotypes of 95 individuals (18–20 individuals per population) for 21 SNPs putatively under selection with environmental scores on a bioclimatic gradient, using 1 × 1 km² grid cells as sampling units. By extrapolating the resulting model to all possible combinations of alleles, we inferred all the geographic cells that were theoretically suitable for a given amount of genetic variance under selection. The inferred distribution range overlapped to a large extent with the realized range of the species (77.46% of overlap), including an accurate prediction of internal gaps and range borders. Our results suggest an adaptability threshold determined by the amount of genetic variation available that would be required to warrant adaptation beyond a certain limit of environmental variation. These results support the idea that the expansion of a species’ range can be ultimately linked to the arising of new variants under selection (either newly selected variants from standing genetic variation or innovative mutations under selection).

中文翻译：

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不同选择下的位点环境关联建模预测蜥蜴的分布范围

在物种范围的历史构建过程中，个体殖民者不得不面对不同的生态挑战，物种扩大范围的能力可能取决于进化提供的适应性遗传变异总量。我们开始尝试通过选择下遗传多样性的地理分布来预测整个物种的范围，以增加我们对定义范围和潜在遗传学作用的理解。我们对西地中海蜥蜴Psammodromus algirus 的五个种群进行了采样它们栖息在明显的温度和降水环境梯度中。我们将 95 个个体（每个群体 18-20 个个体）的 21 个 SNP 的基因型与生物气候梯度上的环境评分相关联，使用 1 × 1 km ² 网格单元作为采样单元。通过将得到的模型外推到所有可能的等位基因组合，我们推断出理论上适合给定数量的选择遗传变异的所有地理细胞。推断的分布范围与物种的实际分布范围（重叠的 77.46%）在很大程度上重叠，包括对内部间隙和范围边界的准确预测。我们的结果表明，适应性阈值由可用的遗传变异量决定，这需要保证超出一定的环境变异限度的适应。