DISSERTATION RESEARCH: Effects of Reduced Population Size on the Genomics of Adaptation during Drosophila Experimental Evolution

众所周知，种群规模的缩小以及由此导致的近亲交配会降低对选择的功能性反应。本研究测量了近亲交配对普通实验室果蝇选择的基因组影响。大多数动物研究使用的是近亲繁殖的实验室种群，但对于像人类这样种群规模很大的物种来说，这种近亲繁殖的动物可能不是很好的研究模型。了解近亲交配的基因组效应将有助于阐明正在进行密集选择的小种群的困境。这对于像保护这样的应用环境非常重要，因为濒危物种的种群通常很少。这项工作还将帮助研究人员了解人口如何适应新的、有压力的环境。这项研究涉及对维持在小人口普查规模的近30个果蝇种群的混合DNA进行测序。这些种群中有一半接受了抗饥性的强选择，而其余种群没有直接进行选择。在这些近亲交配的果蝇中，对强选择的功能反应已经被证明是受损的。基因组分析将揭示削弱它们对选择反应的遗传机制。然后，这些基因组研究结果将与维持在更大种群规模下的果蝇种群的基因组研究进行比较。这种比较将揭示近亲交配导致选择反应减弱的遗传基础。

Reduced population size, and the inbreeding that results from it, is known to reduce the functional response to selection. The present research measures the genomic impact of inbreeding on selection in the common lab fruit fly. Most animal research uses laboratory populations that are inbred, but such inbred animals may not be good research models for species that have large population sizes like humans. Understanding the genomic effects of inbreeding will help elucidate the plight of small populations undergoing intense selection. This is of great importance for such applied settings as conservation since endangered species often have very small populations. The work will also help researchers understand how populations adapt to novel, stressful environments. The research involves sequencing pooled DNA from nearly 30 Drosophila populations maintained at small census sizes. Half of these populations were subjected to strong selection for starvation resistance, while no selection was directly imposed on the remainder. The functional response to strong selection has already been shown to be impaired in these inbred flies. Genomic analysis will reveal the genetic machinery that has impaired their response to selection. These genomic findings will then be compared to genomic studies of fruit fly populations maintained at much larger population sizes. The comparison will reveal the genetic basis of reduced response to selection with inbreeding.