School of Science, Technology and Engineering, University of the Sunshine Coast, Petrie, QLD, Australia.
Department of Biology, Edward Grey Institute of Field Ornithology, University of Oxford, Oxford, UK.
Sci Rep. 2024 Sep 3;14(1):20426. doi: 10.1038/s41598-024-71364-9.
Identifying mechanisms that drive population divergence under varying geographic and ecological scenarios can inform our understanding of evolution and speciation. In particular, analysis of genetic data from island populations with known colonisation timelines allows us to identify potential source populations of diverging island subspecies and current relationships among populations. Silvereyes (Zosterops lateralis) are a small passerine that have served as a valuable study system to investigate evolutionary patterns on both large and small geographic scales. We examined genetic relatedness and diversity of two silvereye subspecies, the mainland Z. l. cornwalli and island Z. l. chlorocephalus, and used 18 077 single nucleotide polymorphisms (SNPs), to compare locations across southeast Queensland, Australia. Although silvereyes are prolific island colonisers our findings revealed population divergence over relatively small spatial scales was strongly influenced by geographic isolation mediated by water barriers. Strong genetic connectivity was displayed between mainland sites, but minimal inter-island connectivity was shown despite comparable sampling distances. Genetic diversity analysis showed little difference in heterozygosity between island and mainland populations, but lower inbreeding scores among the island populations. Our study confirmed the range of the Z. l. chlorocephalus subspecies throughout the southern Great Barrier Reef. Our results show that water barriers and not geographic distance per se are important in driving incipient divergence in island populations. This helps to explain the relatively high number of phenotypically differentiated, but often geographically proximate, island silvereye subspecies compared to a lower number of phenotypically less well-defined Australian continental subspecies.
确定在不同地理和生态环境下导致种群分歧的机制，可以帮助我们理解进化和物种形成。特别是，对具有已知殖民时间线的岛屿种群的遗传数据进行分析，可以确定正在分化的岛屿亚种的潜在起源种群，以及种群之间的当前关系。银眼鸟（Zosterops lateralis）是一种小型雀形目鸟类，是研究大、小地理尺度进化模式的宝贵研究系统。我们研究了两种银眼鸟亚种，即大陆 Z. l. cornwalli 和岛屿 Z. l. chlorocephalus 的遗传亲缘关系和多样性，并使用了 18077 个单核苷酸多态性（SNP），来比较澳大利亚昆士兰州东南部的不同地点。尽管银眼鸟是大量的岛屿殖民者，但我们的研究结果表明，相对较小的空间尺度上的种群分歧主要受到水障介导的地理隔离的影响。大陆站点之间显示出很强的遗传连通性，但尽管采样距离相当，岛屿之间的连通性却很小。遗传多样性分析表明，岛屿和大陆种群之间的杂合度差异不大，但岛屿种群的近交分数较低。我们的研究证实了 Z. l. chlorocephalus 亚种在大堡礁南部的分布范围。我们的研究结果表明，水障而不是地理距离本身是驱动岛屿种群初始分歧的重要因素。这有助于解释为什么与澳大利亚大陆亚种相比，具有表型分化但通常地理上相近的岛屿银眼鸟亚种数量相对较高，而表型差异较小的亚种数量较低。
