Dissertation Research: Separating Population Structure from Population History in South American Cactophylic Drosophila of the Cluster buzzatii

9701809 Templeton解释物种分布是生物地理学的主要挑战之一。历史和生态因素可以解释为什么有些物种分布广泛，而另一些物种分布有限。本研究将调查分布在南美洲东部大部分干旱地区的两种果蝇。sersophila serido是一个由至少5个假定物种组成的超物种复合体，在这个范围内表现出显著的变化。另一方面，D. buzzatii没有表现出多样化的迹象。这些模式是如何从种群结构等当前力量和种群历史等过去力量中产生的，将通过分析这些物种范围内的DNA序列变异（mtDNA和核）来解决。所采用的程序是新的，应区分影响分布的历史因素和生态因素。所开发的方法将适用于一般物种，以帮助了解影响物种分布的基本力量。需要像这样的实证研究来检验这些假设的有效性。这项研究还将提供过去气候变化期间南美洲干旱地区分布的信息，这与保护有关。

9701809 Templeton Explaining species distributions is one of the major challenges in biogeography. Historical and ecological factors may explain why some species are widespread while others have restricted distributions. This study will investigate two fruitfly species distributed through most of the dry areas in east South America. Drosophila serido, a superspecies complex composed of at least 5 putative species, shows remarkable variation throughout this range. On the other hand, D. buzzatii shows no sign of diversification. How these patterns result from present forces such as population structure and past forces such as population history will be addressed by the analysis of DNA sequence variation (mtDNA and nuclear) across the range of these species. The procedure to be used is new and should differentiate historical from ecological factors affecting distributions. The methods developed will apply to species in general, to help understand basic forces affecting the distributions of species. Empirical studies such as this one are needed to test the validity of the assumptions. This study will also provide information on the distribution of dry areas during past climate changes in South America, which is relevant to conservation.