Taylor Scott A, Curry Robert L, White Thomas A, Ferretti Valentina, Lovette Irby
Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, 159 Sapsucker Woods Road, Ithaca, New York 14850; Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14850.
Evolution. 2014 Nov;68(11):3066-81. doi: 10.1111/evo.12510. Epub 2014 Sep 19.
Studies of hybrid zone dynamics often investigate a single sampling period and draw conclusions from that temporal snapshot. Stochasticity can, however, result in loci with spurious outlier patterns, which is exacerbated by limited temporal or geographic sampling. Comparing admixed populations from different geographic regions is one way to detect repeatedly divergent genomic regions potentially involved in reproductive isolation. Temporal comparisons also allow us to control partially for the role of stochasticity, but the power of temporal sampling has not yet been adequately explored. In North America, black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadees hybridize in a contact zone extending from New Jersey to Kansas. The hybrid zone is likely maintained by strong intrinsic selection against hybrids, and it is moving north. We used a reduced representation genomic approach and temporally spaced sampling-two samples of ∼80 individuals separated by a decade-to determine the pattern and consistency of selection and genomic introgression in the chickadee hybrid zone. We report consistently low introgression for highly divergent loci between P. atricapillus and P. carolinensis in this moving hybrid zone. This is strong evidence that these loci may be linked to genomic regions involved in reproductive isolation between chickadees.
杂交带动态的研究通常调查单个采样期，并从该时间快照得出结论。然而，随机性可能导致出现具有虚假异常模式的基因座，有限的时间或地理采样会加剧这种情况。比较来自不同地理区域的混合种群是检测可能参与生殖隔离的反复分化的基因组区域的一种方法。时间比较也使我们能够部分控制随机性的作用，但时间采样的功效尚未得到充分探索。在北美，黑顶山雀（Poecile atricapillus）和卡罗来纳山雀（P. carolinensis）在从新泽西州到堪萨斯州的接触带杂交。杂交带可能通过对杂交种的强烈内在选择而维持，并且正在向北移动。我们使用了一种简化代表性基因组方法和时间间隔采样——相隔十年的两个约80个个体的样本——来确定山雀杂交带中选择和基因组渐渗的模式及一致性。我们报告说，在这个移动的杂交带中，黑顶山雀和卡罗来纳山雀之间高度分化的基因座的渐渗一直很低。这有力地证明，这些基因座可能与山雀之间参与生殖隔离的基因组区域有关。
