DISSERTATION RESEARCH: Reproductive Incompatibility by Compensatory Mutations.

维持较小规模的种群可能会导致有害突变的积累，从而破坏个体的适应性。然而，随后回到大的种群规模可能会导致有益的突变固定在其他基因座上，以弥补这些负面影响。这种有利的结合可能在异交过程中被破坏，从而导致杂种的适合度下降，并代表着形成新物种的第一步。这项研究是首次对代偿性突变在生殖不亲和性进化中的作用进行实验测试。利用线虫模型系统线虫，这个项目试图：1)通过敲除一个关键的DNA错配修复基因，使多个品系在小种群规模下保持有害突变积累的机制；2)通过在大种群规模下积累补偿突变，在突变退化的品系中启动适应度恢复，从而创建品系特异性共适应基因复合体；以及3)测试杂交后代中降低的适合度。这项研究将测试基因座间的相互作用在生殖不亲和性进化中的作用，评估一个关键的物种形成模型的有效性，并对保护管理实践具有指导意义。

The maintenance of populations at small sizes can lead to the accumulation of deleterious mutations that undermine the fitness of individuals. However, subsequent return to large population size can result in the fixation of beneficial mutations at other loci that compensate for these negative effects. Such an advantageous association can be disrupted during outcrossing, thereby leading to a fitness decline in hybrids and representing a first step in the formation of new species. This research represents the first experimental test of the role of compensatory mutations in the evolution of reproductive incompatibility. Using the nematode model system C. elegans, this project attempts to: 1) subject multiple lines to a regime of deleterious mutation accumulation by maintenance at small population sizes with a knockout of a key DNA mismatch repair gene; 2) initiate fitness recovery in mutationally degraded lines via the accumulation of compensatory mutations under large population sizes, thereby creating line-specific coadapted gene complexes and 3) test for diminished fitness in hybrid progeny. This study will test the role of inter-locus gene interactions in the evolution of reproductive incompatibility, evaluate the validity of a key model of speciation, and have implications for conservation management practices.