The Molecular Basis of Coadaptation and Hybrid Breakdown

当来自遗传分化群体的动物或植物进行杂交时，所产生的杂交往往表现出比它们的亲本更差的表现(杂交失败)。这在第二代(F2)杂交种中尤其如此，在这种杂交种中，不相容的基因型可能通过重组而出现。这项拟议的工作使用海洋桡足类老虎作为模型系统来分析杂交崩溃的分子机制。这个项目包括两个部分。首先，实验聚焦于核基因和线粒体基因之间的相互作用，验证了杂交扰乱线粒体能量产生的假设。这项研究的第二部分验证了这样的假设，即杂交扰乱了rRNA基因的转录，从而导致杂交后代蛋白质合成速度降低(和性能降低)。杂交种的破坏在自然界中广泛存在，在医学、农业和保护生物学中具有重要的影响。该项目的结果可能有助于理解：(1)已知的与线粒体功能中断的线粒体DNA和核基因突变有关的人类疾病的数量不断增加，(2)基因相互作用在农业中的作用，在农业中，强有力的F1杂交菌株往往导致表现不佳的F2杂交菌株，以及(3)野生动物管理和保护措施应该在多大程度上限制生物在地理位置之间的移动。该项目还将为本科生、研究生和博士后研究人员提供极好的培训机会。

When animals or plants from genetically divergent populations interbreed, the resulting hybrids often show reduced performance (hybrid breakdown) relative to their parents. This is especially true in second generation (F2) hybrids, where incompatible genotypes may arise via recombination. The proposed work uses the marine copepod Tigriopus californicus as a model system for analyses of the molecular mechanisms underlying hybrid breakdown. This project has two parts. In the first, experiments focus on interactions between nuclear and mitochondrial genes, testing the hypothesis that hybridization disrupts energy production in mitochondria. The second part of the study tests the hypothesis that hybridization disrupts transcription of rRNA genes and this results in reduced rates of protein synthesis (and reduced performance) in hybrids. Hybrid breakdown is widespread in nature and has important ramifications in medicine, agriculture and conservation biology. Results from this project may aid in understanding: (1) the growing number of human diseases known to be associated with mtDNA and nuclear gene mutations which disrupt mitochondrial function, (2) the role of gene interactions in agriculture, where vigorous F1 hybrid strains often give rise to poor-performing F2 hybrids, and (3) the extent to which wildlife management and conservation practices should restrict movement of organisms among geographic locales. The project will also provide excellent training opportunities for undergraduate, graduate and postdoctoral researchers.