Understanding the processes that underlie the development of population genetic structure is central to the study of evolution. Patterns of genetic structure, in turn, can reveal signatures of isolation by distance (IBD), barriers to gene flow, or even the genesis of speciation. However, it is unclear how severe range restriction might impact the processes that dominate the development of genetic structure. In narrow endemic species, is population structure likely to be adaptive in nature, or rather the result of genetic drift? In this study, we investigated patterns of genetic diversity and structure in the narrow endemic Hayden's ringlet butterfly. Specifically, we asked to what degree genetic structure in the Hayden's ringlet can be explained by IBD, isolation by resistance (IBR) (in the form of geographic or ecological barriers to migration between populations), and isolation by environment (in the form of differences in host plant availability and preference). We employed a genotyping-by-sequencing (GBS) approach coupled with host preference assays, Bayesian modelling, and population genomic analyses to answer these questions. Our results suggest that despite their restricted range, levels of genetic diversity in the Hayden's ringlet are comparable to those seen in more widespread butterfly species. Hayden's ringlets showed a strong preference for feeding on grasses relative to sedges, but neither larval preference nor potential host availability at sampling sites correlated with genetic structure. We conclude that geography, in the form of IBR and simple IBD, was the major driver of contemporary patterns of differentiation in this narrow endemic species.

中文翻译：

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尽管海登小环 (Coenonympha haydenii) 的特有性狭窄且生态专业化有限，但仍具有相当大的遗传多样性和结构

了解种群遗传结构发展的过程是进化研究的核心。反过来，遗传结构模式可以揭示距离隔离（IBD）的特征、基因流动的障碍，甚至物种形成的起源。然而，目前尚不清楚严格的范围限制可能会如何影响主导遗传结构发育的过程。在狭窄的特有物种中，种群结构是否可能本质上是适应性的，或者更确切地说是遗传漂变的结果？在这项研究中，我们研究了狭义地方性海登小环蝴蝶的遗传多样性和结构模式。具体来说，我们询问海登小环中的遗传结构在多大程度上可以用 IBD、抗性隔离（IBR）（以种群间迁移的地理或生态障碍的形式）和环境隔离（以差异的形式）来解释。宿主植物的可用性和偏好）。我们采用测序基因分型 (GBS) 方法，结合宿主偏好分析、贝叶斯建模和群体基因组分析来回答这些问题。我们的研究结果表明，尽管海登小环的范围有限，但其遗传多样性水平与更广泛的蝴蝶物种的遗传多样性水平相当。相对于莎草，海登小卷表现出对草类的强烈偏好，但幼虫偏好和采样点的潜在宿主可用性均与遗传结构无关。我们得出的结论是，以 IBR 和简单 IBD 形式出现的地理因素是这一狭窄特有物种当代分化模式的主要驱动力。