Dissertation Research: Evolutionary Genetics of the Speciation Gene, Maternal Hybrid Rescue

物种形成--将一个物种一分为二--创造了生物多样性。随着两个杂交种群进化出阻止基因交换的机制，它们成为具有独立进化命运的新物种。物种间的遗传交换往往受到其杂交后代的不育或不能存活的限制。至少在动物身上，这样的杂交问题是由遗传不相容引起的：当把物种A的一些基因放在一起进行杂交时，物种A的一些基因不再与物种B的基因正常运作。这里提出的工作将调查导致果蝇物种之间杂交死亡的基因。利用这些模式生物中可用的遗传和发育技术，该项目将首先识别杂交种中错误沟通的基因的DNA序列，然后描述它们之间致命的相互作用。这些实验将集中在一个候选的“物种形成基因”的作用上，即母体杂交拯救。一旦在分子水平上确定，人们就可以问，这些基因的序列在物种之间是如何变化的，为什么它们的产物在杂交中不能正确地相互作用，以及是什么进化力量驱动了它们的分歧。只有通过从基因上解剖杂交问题，生物学家才能开始了解遗传不亲和性的进化，从而了解新物种的起源。

Speciation - the splitting of one species into two - creates biodiversity. As two interbreeding populations evolve mechanisms preventing the exchange of genes, they become new species with independent evolutionary fates. Genetic exchange between species is often limited by the sterility or inviability of their hybrids. At least in animals, such hybrid problems are caused by genetic incompatibilities: some genes from species A no longer function properly with those of species B when brought together in hybrids. The work proposed here will investigate the genes that cause hybrid inviability between species of the fruitfly Drosophila. Using the genetic and developmental techniques available in these model organisms, the project will first identify the DNA sequences of genes that miscommunicate in hybrids and, second, characterize their lethal interaction. The experiments will focus on the role of one candidate "speciation gene", maternal hybrid rescue. Once identified at the molecular level, one can then ask how the sequences of such genes changed between species, why their products fail to properly interact in hybrids, and what evolutionary forces drove their divergence. Only by genetically dissecting hybrid problems can biologists begin to understand the evolution of genetic incompatibilities and thus the origin of new species.