Genomic variation in cline shape across a hybrid zone

Ecology and Evolution

Sarah E. Kingston¹  Robert W. Jernigan³  William F. Fagan⁴  David Braun² 

[1] Vertebrate Zoology, Smithsonian Institution, National Museum of Natural History, Washington, District of Columbia, USA;Plateau Land and Wildlife Management, Dripping Springs, Texas, USA;Department of Mathematics and Statistics, American University, Washington, District of Columbia, USA;Department of Biology, University of Maryland, College Park, Maryland, USA

关键词: AFLP;    gene flow;    hybridization;    introgression;    isozyme;    mitochondrial DNA;    Pipilo maculatus;    Pipilo ocai;    tension zone model;    towhee;   

DOI  :  10.1002/ece3.375

来源: Wiley

【 摘 要 】

Abstract

Hybrid zones are unique biological interfaces that reveal both population level and species level evolutionary processes. A genome-scale approach to assess gene flow across hybrid zones is vital, and now possible. In Mexican towhees (genus Pipilo), several morphological hybrid gradients exist. We completed a genome survey across one such gradient (9 populations, 140 birds) using mitochondrial DNA, 28 isozyme, and 377 AFLP markers. To assess variation in introgression among loci, cline parameters (i.e., width, center) for the 61 clinally varying loci were estimated and compiled into genomic distributions for tests against three empirical models spanning the range of observed cline shape. No single model accounts for observed variation in cline shape among loci. Numerous backcross individuals near the gradient center confirm a hybrid origin for these populations, contrary to a previous hypothesis based on social mimicry and character displacement. In addition, the observed variation does not bin into well-defined categories of locus types (e.g., neutral vs. highly selected). Our multi-locus analysis reveals cross-genomic variation in selective constraints on gene flow and locus-specific flexibility in the permeability of the interspecies membrane.

【 授权许可】

CC BY   
© 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.

Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.