Brisson Jennifer A, De Toni Daniela Cristina, Duncan Ian, Templeton Alan R
Campus Box 1137, Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
Evolution. 2005 May;59(5):1046-59.
Drosophila polymorpha is a widespread species that exhibits abdominal pigmentation variation throughout its range. To gain insight into this variation we combined phenotypic and genotypic data to test a series of nested hypotheses. First, we tested the null hypothesis that geographic variation in pigmentation is due to neutral factors. We used nested clade analysis to examine the distribution of haplotypes from a nuclear and a mitochrondrial locus. Restricted gene flow via isolation by distance, the primary inference of this phylogeographic analysis, was then used to generate and test the hypothesis of increasing average abdominal pigmentation difference with increasing geographic distance. We found no correlation between geographic distance and phenotypic distance. We then tested the hypothesis that pigmentation is affected by environmental differences among localities. We found a significant effect of habitat type on the average abdominal pigmentation phenotype of different localities. Finally, we tested the hypothesis that pigmentation in D. polymorpha is associated with desiccation resistance. We found that dark individuals of both sexes survived significantly longer in a desiccating environment than light individuals. These patterns combined lead us to hypothesize that abdominal pigmentation variation in D. polymorpha is important in mediating the organism's interactions with local ecological factors.
多型果蝇是一种分布广泛的物种，在其分布范围内表现出腹部色素沉着的变化。为了深入了解这种变化，我们结合了表型和基因型数据来检验一系列嵌套假设。首先，我们检验了色素沉着的地理变异是由中性因素导致的零假设。我们使用嵌套进化枝分析来检查来自一个核基因座和一个线粒体基因座的单倍型分布。通过距离隔离导致的有限基因流动，是这种系统地理学分析的主要推断，随后被用于生成和检验随着地理距离增加平均腹部色素沉着差异也增加的假设。我们发现地理距离与表型距离之间没有相关性。然后我们检验了色素沉着受不同地点环境差异影响的假设。我们发现栖息地类型对不同地点的平均腹部色素沉着表型有显著影响。最后，我们检验了多型果蝇的色素沉着与抗干燥能力相关的假设。我们发现，在干燥环境中，深色的雌雄个体比浅色个体存活时间显著更长。这些模式综合起来使我们推测，多型果蝇腹部色素沉着的变化在介导生物体与当地生态因素的相互作用中很重要。
