Molecular Basis of F2 Hybrid Breakdown

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Geographically isolated populations diverge genetically over time and may ultimately become new species. Early in the process, when the populations can still interbreed, genetic incompatibilities often result in loss of fitness in interpopulation hybrids. The proposed research uses the marine copepod, Tigriopus californicus, to examine molecular mechanisms underlying loss of fitness in hybrids. Recent work has shown that hybrids are characterized by reduced activity of the electron transport system in mitochondria, the energy producing part of all animal cells. Experiments are proposed to extend our understanding of mitochondrial dysfunction in hybrids using two recently developed molecular tools, RNA interference (to manipulate gene expression) and whole transcriptome sequencing (to obtain a global view of gene expression). Together, these will tease apart changes in gene expression in response to genome hybridization versus changes in response to the external environment. These methods will be used to compare the responses of natural populations and laboratory hybrids to determine the genes involved in population incompatibility. Although the proposed work is primarily motivated by questions in evolutionary biology, its focus on mitochondrial dysfunction is of broad interest throughout biomedical sciences, especially in the fields of aging and nuclear transplantation. The investigations will provide unique training opportunities for undergraduate, graduate and postdoctoral researchers seeking to integrate studies of molecular biology, physiology, and genetics to address important questions in biology. The results of the work (and the methods employed) also serve as starting points for diverse outreach activities including public lectures, curriculum development in molecular ecology, and development of K-12 laboratory activities implemented in public schools by an environmental education organization.