Solmundson Kirsten, Bowman Jeff, Manseau Micheline, Taylor Rebecca S, Keobouasone Sonesinh, Wilson Paul J
Environmental & Life Sciences Graduate Program Trent University Peterborough Ontario Canada.
Wildlife Research and Monitoring Section, Ontario Ministry of Natural Resources and Forestry Trent University Peterborough Ontario Canada.
Ecol Evol. 2023 Jul 7;13(7):e10278. doi: 10.1002/ece3.10278. eCollection 2023 Jul.
Caribou () have experienced dramatic declines in both range and population size across Canada over the past century. Boreal caribou (), 1 of the 12 Designatable Units, has lost approximately half of its historic range in the last 150 years, particularly along the southern edge of its distribution. Despite this overall northward contraction, some populations have persisted at the trailing range edge, over 150 km south of the continuous boreal caribou range in Ontario, along the coast and nearshore islands of Lake Superior. The population history of caribou along Lake Superior remains unclear. It appears that these caribou likely represent a remnant distribution at the trailing edge of the receding population of boreal caribou, but they may also exhibit local adaptation to the coastal environment. A better understanding of the population structure and history of caribou along Lake Superior is important for their conservation and management. Here, we use high-coverage whole genomes ( = 20) from boreal, eastern migratory, and barren-ground caribou sampled in Manitoba, Ontario, and Quebec to investigate population structure and inbreeding histories. We discovered that caribou from the Lake Superior range form a distinct group but also found some evidence of gene flow with the continuous boreal caribou range. Notably, caribou along Lake Superior demonstrated relatively high levels of inbreeding (measured as runs of homozygosity; ROH) and genetic drift, which may contribute to the differentiation observed between ranges. Despite inbreeding, caribou along Lake Superior retained high heterozygosity, particularly in genomic regions without ROH. These results suggest that they present distinct genomic characteristics but also some level of gene flow with the continuous range. Our study provides key insights into the genomics of the southernmost range of caribou in Ontario, beginning to unravel the evolutionary history of these small, isolated caribou populations.
在过去的一个世纪里，加拿大的驯鹿（）在分布范围和种群数量上都经历了显著下降。北方驯鹿（）是12个可指定单元之一，在过去150年里，其历史分布范围已丧失了约一半，尤其是在其分布的南部边缘。尽管总体上向北收缩，但一些种群仍在分布范围的边缘地带存续，位于安大略省北方驯鹿连续分布范围以南150多公里处，苏必利尔湖沿岸及近岸岛屿。苏必利尔湖沿岸驯鹿的种群历史仍不清楚。这些驯鹿似乎可能代表了北方驯鹿种群退缩后边缘地带的残余分布，但它们也可能表现出对沿海环境的局部适应。更好地了解苏必利尔湖沿岸驯鹿的种群结构和历史对其保护和管理至关重要。在此，我们使用从马尼托巴省、安大略省和魁北克省采集的北方、东部迁徙和贫瘠地驯鹿的高覆盖度全基因组（ = 20）来研究种群结构和近亲繁殖历史。我们发现，来自苏必利尔湖分布范围的驯鹿形成了一个独特的群体，但也发现了一些与北方驯鹿连续分布范围存在基因流动的证据。值得注意的是，苏必利尔湖沿岸的驯鹿表现出相对较高水平的近亲繁殖（以纯合子连续片段衡量；ROH）和遗传漂变，这可能导致了不同分布范围之间观察到的差异。尽管存在近亲繁殖，苏必利尔湖沿岸的驯鹿仍保持着较高的杂合度，尤其是在没有ROH的基因组区域。这些结果表明，它们呈现出独特的基因组特征，但也与连续分布范围存在一定程度的基因流动。我们的研究为安大略省最南端驯鹿的基因组学提供了关键见解，开始揭示这些小型孤立驯鹿种群的进化历史。
