Mammalian Ecology and Conservation Unit, Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis, California, USA.
USDA Forest Service, Rocky Mountain Research Station, National Genomics Center for Wildlife and Fish Conservation, Missoula, Montana, USA.
Mol Ecol. 2024 Jul;33(13):e17418. doi: 10.1111/mec.17418. Epub 2024 Jun 7.
Human-facilitated introductions of nonnative populations can lead to secondary contact between allopatric lineages, resulting in lineage homogenisation or the formation of stable hybrid zones maintained by reproductive barriers. We investigated patterns of gene flow between the native Sacramento Valley red fox (Vulpes vulpes patwin) and introduced conspecifics of captive-bred origin in California's Central Valley. Considering their recent divergence (20-70 kya), we hypothesised that any observed barriers to gene flow were primarily driven by pre-zygotic (e.g. behavioural differences) rather than post-zygotic (e.g. reduced hybrid fitness) barriers. We also explored whether nonnative genes could confer higher fitness in the human-dominated landscape resulting in selective introgression into the native population. Genetic analysis of red foxes (n = 682) at both mitochondrial (cytochrome b + D-loop) and nuclear (19,051 SNPs) loci revealed narrower cline widths than expected under a simulated model of unrestricted gene flow, consistent with the existence of reproductive barriers. We identified several loci with reduced introgression that were previously linked to behavioural divergence in captive-bred and domestic canids, supporting pre-zygotic, yet possibly hereditary, barriers as a mechanism driving the narrowness and stability of the hybrid zone. Several loci with elevated gene flow from the nonnative into the native population were linked to genes associated with domestication and adaptation to human-dominated landscapes. This study contributes to our understanding of hybridisation dynamics in vertebrates, particularly in the context of species introductions and landscape changes, underscoring the importance of considering how multiple mechanisms may be maintaining lineages at the species and subspecies level.
人类介导的非本地种群的引入可能导致异域谱系之间的二次接触，从而导致谱系同质化或由生殖障碍维持的稳定杂交区的形成。我们调查了加利福尼亚州中央谷中本地萨克拉门托谷红狐（Vulpes vulpes patwin）和引入的圈养同种狐狸之间的基因流动模式。考虑到它们最近的分化（20-70 千年前），我们假设任何观察到的基因流动障碍主要是由前合子（例如行为差异）而不是后合子（例如杂种适应性降低）障碍驱动的。我们还探讨了非本地基因是否可以在人类主导的景观中赋予更高的适应性，从而导致选择性渐渗到本地种群中。对红狐（n = 682）的线粒体（细胞色素 b + D 环）和核（19051 个 SNPs）基因座的遗传分析表明，与不受限制的基因流动模拟模型下预期的狭窄程度相比，其变异性更窄，这与生殖障碍的存在一致。我们确定了几个基因渐渗程度降低的基因座，这些基因座与圈养和家养犬科动物的行为分化有关，支持前合子，但可能是遗传性障碍作为驱动杂交区狭窄和稳定的机制。从非本地种群到本地种群的几个基因流动增加的基因座与与驯化和适应人类主导景观相关的基因有关。本研究有助于我们理解脊椎动物的杂交动态，特别是在物种引入和景观变化的背景下，强调了考虑多种机制如何维持物种和亚种水平的谱系的重要性。
