INCIPIENT SPECIATION DESPITE LITTLE ASSORTATIVE MATING: THE YELLOW-RUMPED WARBLER HYBRID ZONE
INCIPIENT SPECIATION DESPITE LITTLE ASSORTATIVE MATING: THE YELLOW-RUMPED WARBLER HYBRID ZONE
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DOI：
10.1111/j.1558-5646.2009.00777.x
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发表时间：
2009-12-01
期刊：
影响因子：
3.3
通讯作者：
Irwin, Darren E.
中科院分区：
文献类型：
--
作者：
Brelsford, Alan;Irwin, Darren E.
最近分化的分类群之间的杂交区是物种形成研究的天然实验室，使我们能够确定不同类型之间是否存在生殖隔离以及这种隔离的原因。我们提出了一个典型的鸟类杂交区在北美的两个亚种的黄腰林莺(Dendroica Coronata)的研究。虽然之前的工作表明线粒体DNA在这个杂交区的分化很小，但我们发现了两个核基因座(一个是性别连锁的，一个是常染色体的)，它们在杂交区显示了固定的差异，这与羽毛变异的模式非常一致。杂交区的时间稳定性和有限的宽度，以及位于区中央的这两个诊断标记之间的显著连锁不平衡，表明这些群体之间存在适度的生殖隔离，估计选择强度保持在18%。配对数据表明，分类交配要么非常弱，要么没有，这表明这种生殖隔离在很大程度上是由于交配后的障碍。因此，尽管进行了广泛的杂交，但这两种形式是不同的进化群体，携带着不同适应高峰的基因，这种情况似乎相对稳定。
Hybrid zones between recently diverged taxa are natural laboratories for speciation research, allowing us to determine whether there is reproductive isolation between divergent forms and the causes of that isolation. We present a study of a classic avian hybrid zone in North America between two subspecies of the yellow-rumped warbler (Dendroica coronata). Although previous work has shown very little differentiation in mitochondrial DNA across this hybrid zone, we identified two nuclear loci (one sex-linked and one autosomal) that show fixed differences across the hybrid zone, in a close concordance with patterns of plumage variation. Temporal stability and limited width of the hybrid zone, along with substantial linkage disequilibrium between these two diagnostic markers in the center of the zone, indicate that there is moderate reproductive isolation between these populations, with an estimated strength of selection maintaining the zone of 18%. Pairing data indicate that assortative mating is either very weak or absent, suggesting that this reproductive isolation is largely due to postmating barriers. Thus, despite extensive hybridization the two forms are distinct evolutionary groups carrying genes for divergent adaptive peaks, and this situation appears relatively stable.