Rosenblum Erica Bree
Museum of Vertebrate Zoology, University of California, Berkeley, California 94720, USA.
Am Nat. 2006 Jan;167(1):1-15. doi: 10.1086/498397. Epub 2005 Nov 7.
Ecological transition zones, where organismal phenotypes result from a delicate balance between selection and migration, highlight the interplay of local adaptation and gene flow. Here, I study the response of an entire species assemblage to natural selection across a common ecotone. Three lizard species, distributed along a dramatic environmental gradient in substrate color, display convergent adaptation of blanched coloration on the gypsum dunes of White Sands National Monument. I investigate the role of gene flow in modulating phenotypic response to selection by quantifying color variation and genetic variation across the ecotone. I find species differences in degree of background matching and in genetic connectivity of populations across the ecotone. Differences among species in phenotypic response to selection scale precisely to levels of genetic isolation. Species with higher levels of gene flow across the ecotone exhibit less dramatic responses to selection. Results also reveal a strong signal of ecologically mediated divergence for White Sands lizards. For all species, phenotypic variation is better explained by habitat similarity than genetic similarity. Convergent evolution of blanched coloration at White Sands clearly reflects the action of strong divergent selection; however, adaptive response appears to be modulated by gene flow and demographic history and can be predicted by divergence-with-gene-flow models.
生态过渡带中，生物体表型是由选择与迁移之间的微妙平衡所导致的，这突出了局部适应与基因流之间的相互作用。在此，我研究了整个物种组合对跨越一个共同生态交错带的自然选择的响应。三种蜥蜴物种沿着底物颜色的剧烈环境梯度分布，在白沙国家纪念区的石膏沙丘上呈现出趋同的白化体色适应。我通过量化生态交错带上的颜色变异和遗传变异，来研究基因流在调节对选择的表型响应中的作用。我发现生态交错带上各物种在背景匹配程度和种群遗传连通性方面存在差异。物种对选择的表型响应差异精确地与遗传隔离水平相对应。在生态交错带上基因流水平较高的物种对选择的响应不那么显著。结果还揭示了白沙蜥蜴存在由生态介导的分化的强烈信号。对于所有物种而言，栖息地相似性比遗传相似性能更好地解释表型变异。白沙地区白化体色的趋同进化清楚地反映了强烈的趋异选择的作用；然而，适应性响应似乎受到基因流和种群历史的调节，并且可以通过带基因流的分化模型进行预测。
