Abstract

The montane sky islands of the Great Basin are characterized by unique, isolated habitats and communities that likely are vulnerable to extirpation with environmental change. A subspecies of yellow pine chipmunk, the Humboldt yellow pine chipmunk (Tamias amoenus celeris), is associated with the whitebark and limber pine forests of the Pine Forest Range (PFR) in Nevada. We sampled T. amoenus and least chipmunks (T. minimus) from the isolated PFR and compared genetic diversity between these populations and more “mainland” populations, including other subspecies of chipmunks. Given the high frequency of hybridization in Tamias, we tested for hybridization between T. amoenus and T. minimus in the PFR. We examined phylogenetic relationships, population divergence and diversity, and screened populations for a common pathogen, Borrelia hermsii, to gain insight into population health. We found T. amoenus of the PFR are closely related to T. amoenus in the Warner Mountains and Sierra Nevada, but maintain substantively lower genetic variation. Microsatellite analyses show PFR T. amoenus are highly genetically differentiated from other populations. In contrast, PFR T. minimus had higher genetic diversity that was comparable to the other T. minimus population we sampled. Pathogen screening revealed that T. amoenus carried higher pathogen loads than T. minimus in the PFR, although the prevalence of infection was similar to other Tamias populations. Our assessment of habitat associations suggests that the Humboldt yellow pine chipmunk almost entirely is restricted to the conifer systems of the PFR, while least chipmunks are prevalent in the other forests. Our work highlights the need for continued conservation and research efforts to identify how response to environmental change can be facilitated in isolated species and habitats.

中文翻译：

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迷失在艾树海中：Tamias amoenus 孤立山地种群的比较遗传评估

摘要

大盆地的山地天空岛屿以独特、孤立的栖息地和社区为特征，很可能会随着环境变化而灭绝。黄松花栗鼠的一个亚种，洪堡黄松花栗鼠 ( Tamias amoenus celeris )，与内华达州松林山脉 (PFR) 的白皮和松林有关。我们从孤立的 PFR 中采集了T. amoenus和 least chipmunks ( T. minimus )，并比较了这些种群与更多“大陆”种群（包括花栗鼠的其他亚种）之间的遗传多样性。鉴于Tamias的杂交频率很高，我们测试了T. amoenus和T. minimus之间的杂交在 PFR 中。我们检查了系统发育关系、种群差异和多样性，并针对常见病原体赫氏疏螺旋体对种群进行了筛查，以深入了解种群健康状况。我们发现PFR 的T. amoenus与华纳山脉和内华达山脉的T. amoenus密切相关，但保持显着较低的遗传变异。微卫星分析显示 PFR T. amoenus在遗传上与其他种群高度不同。相比之下，PFR T. minimus具有更高的遗传多样性，与我们采样的其他T. minimus种群相当。病原体筛选显示T. amoenus携带的病原体负荷高于PFR 中的T. minimus ，尽管感染流行率与其他Tamias种群相似。我们对栖息地协会的评估表明，洪堡黄松花栗鼠几乎完全局限于 PFR 的针叶树系统，而最少的花栗鼠在其他森林中普遍存在。我们的工作强调需要继续进行保护和研究工作，以确定如何在孤立的物种和栖息地促进对环境变化的反应。