Center for Veterinary Genetics, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA.
Mol Ecol. 2011 Jan;20(2):326-41. doi: 10.1111/j.1365-294X.2010.04943.x. Epub 2010 Dec 9.
Introduced species can threaten native taxa in multiple ways, including competition and hybridization, which can reduce fitness, alter ecological niches or swamp native genomes. Encroachment and hybridization by introduced species also provide opportunities to study the dynamics of invasiveness and hybridization during early stages following contact. We used 33 microsatellites, 51 single nucleotide polymorphisms and a mtDNA marker to characterize the extent and spatial pattern of encroachment and hybridization between a native, endemic subspecies of red fox (Vulpes vulpes patwin) and an introduced red fox population composed of highly admixed, phylogenetically divergent stock, resulting from a century of domestication. Both nuclear and mtDNA markers indicated that hybridization was primarily restricted to a narrow zone where the two populations came into contact. Although a few introgressed genotypes were detected in the interior of the native range, we found no immigrant foxes or F(1) or F(2) hybrids there, suggesting native foxes excluded introduced individuals. We speculate that the observed interbreeding at the periphery was facilitated by low densities. In total, 98% of mtDNA haplotypes in the native range were native and 96% of the nuclear ancestry was estimated to be native. Although the introduced range had expanded fivefold over the past four decades, native and non-native haplotypes from museum samples collected in and near the native range three decades earlier showed a similar geographic distribution as today, suggesting that the native range and hybrid zone were relatively stable. We hypothesize that the monogamous mating system of red foxes and other wild canids may enhance their resistance to hybridization because of greater fitness consequences associated with mate discrimination.
引入物种可以通过多种方式威胁本地分类群，包括竞争和杂交，这可能会降低适应性、改变生态位或淹没本地基因组。引入物种的侵占和杂交也提供了机会，可以在接触后的早期阶段研究入侵和杂交的动态。我们使用了 33 个微卫星、51 个单核苷酸多态性和一个 mtDNA 标记来描述本地特有亚种红狐（Vulpes vulpes patwin）和由高度混合、系统发育上分化的种群组成的引入红狐种群之间的侵占和杂交的程度和空间模式，这些种群是一个世纪以来驯化的结果。核和 mtDNA 标记都表明，杂交主要局限于两个种群接触的狭窄区域。尽管在本地范围内检测到了少数杂交基因型，但我们没有在那里发现移民狐狸或 F1 或 F2 杂种，这表明本地狐狸排斥了引入的个体。我们推测，在边缘观察到的杂交是由低密度促成的。总的来说，在本地范围内，98%的 mtDNA 单倍型是本地的，96%的核遗传背景估计是本地的。尽管引入的范围在过去四十年中扩大了五倍，但在本地范围内和附近收集的博物馆样本中的本地和非本地单倍型与今天的分布相似，这表明本地范围和杂交区相对稳定。我们假设红狐和其他野生犬科动物的一夫一妻制交配系统可能会增强它们对杂交的抵抗力，因为与伴侣识别相关的适应性后果更大。
