Hybrid swarm between divergent lineages of mule deer (Odocoileus hemionus)

Studies of hybrid zones have revealed an array of evolutionary outcomes, yet the underlying structure is typically characterized as one of three types: a hybrid zone, a hybrid swarm or a hybrid taxon. Our primary objective was to determine which of these three structures best characterizes a zone of hybridization between two divergent lineages of mule deer (Odocoileus hemionus), mule deer and black-tailed deer. These lineages are morphologically, ecologically and genetically distinct, yet hybridize readily along a zone of secondary contact between the east and west slopes of the Cascade Mountains (Washington and Oregon, USA). Using microsatellite and mitochondrial DNA, we found clear evidence for extensive hybridization and introgression between lineages, with varying degrees of admixture across the zone of contact. The pattern of hybridization in this region closely resembles a hybrid swarm; based on data from 10 microsatellite loci, we detected hybrids that extend well beyond the F1 g...对杂交带的相关研究已揭示出多种演化结局，但其核心结构通常可划分为三类：杂交带、杂交群（hybrid swarm）与杂交类群（hybrid taxon）。本研究旨在明确北美骡鹿（Odocoileus hemionus）的两个分化支系——骡鹿与黑尾鹿之间的杂交带，更符合上述三类结构中的哪一种。这两个支系在形态学、生态学与遗传学上均存在显著分化，但在美国喀斯喀特山脉（Cascade Mountains）东西两侧（华盛顿州与俄勒冈州）的次生接触带中，二者可频繁发生杂交。本研究借助微卫星（microsatellite）与线粒体DNA（mitochondrial DNA）标记，发现两支系间存在广泛的杂交与基因渐渗现象，且接触带内的遗传混合程度存在空间异质性。该区域的杂交模式与杂交群特征高度吻合；基于10个微卫星位点的数据，我们检测到的杂交个体远超出F1代（原文未完整）