PDF(Pubmed)
Abstract：
Genetic adaptation is the change of a population toward a phenotype that best fits the present ecological conditions of the environment it inhabits. As environmental conditions change, allele frequencies shift, resulting in different populations of the same species possessing genetic variation and divergent phenotypes. Cooperatively breeding common mole-rats (Cryptomys hottentotus hottentotus) inhabit environments along an aridity gradient in South Africa, which provides an opportunity for local genetic adaptations to occur. Using one mitochondrial gene (cytochrome b) and 3,540 SNP loci across the whole genome, we determined the phylogenetic relationship, population structure and genetic diversity of five populations of C. h. hottentotus located along an aridity gradient. Mitochondrial data identified population-specific clades that were less distinct in the two mesic populations, potentially indicating historical or recent gene flow, or the retention of ancestral haplotypes. Arid and semi-arid populations formed a distinct cluster from the non-arid populations. Genetic diversity and gene flow were higher in arid-dwelling individuals, suggesting greater connectivity and interactions between colonies in arid regions in comparison to mesic ones. Using an Aridity Index, we determined that isolation by environment, rather than isolation by geographical distance, best explains the genetic distance between the populations. Further analyses using target loci may determine if there are differing underlying genetic adaptations among populations of C. h. hottentotus. These analyses could help unravel population differences in response to environmental factors within a subspecies of bathyergid mole-rat and determine the adaptive capacity of this small nonmigratory subterranean rodent species in response to aridification in the face of climate change.
摘要：
遗传适应是种群向最适合其栖息的当前生态条件的表型的变化。随着环境条件的变化,等位基因频率偏移，导致同一物种的不同种群具有遗传变异和不同的表型。在南非，合作繁殖的普通mole鼠（Cryptomyshottentotushottentotus）沿着干旱梯度栖息在环境中，这为当地的基因适应提供了机会。在整个基因组中使用一个线粒体基因（细胞色素b）和3,540个SNP基因座，我们确定了系统发育关系，沿干旱梯度分布的五个C.h.hottentotus种群的种群结构和遗传多样性。线粒体数据确定了在两个mesic种群中差异较小的种群特异性进化枝，可能表明历史或最近的基因流动，或保留祖先单倍型。干旱和半干旱种群与非干旱种群形成了明显的集群。干旱个体的遗传多样性和基因流动较高，表明干旱地区的殖民地之间的连通性和相互作用更大。使用干旱指数，我们决定通过环境隔离，而不是地理距离的孤立，最好地解释了种群之间的遗传距离。使用目标基因座的进一步分析可以确定在C.h.hottentotus种群之间是否存在不同的潜在遗传适应。这些分析可以帮助揭示种群差异，以响应地鼠鼠亚种中的环境因素，并确定这种小型非迁徙地下啮齿动物物种在面对气候变化时对干旱化的适应能力。
