Collaborative Research: Molecular Basis Of Novel Phenotypes Resulting From Interpopulation Hybridization

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Climate change affects the geographic distribution of populations and species and can result in increased opportunities for hybridization between previously isolated populations. Hybridization can have a range of outcomes. Most frequently, hybridization results in loss of fitness (hybrid breakdown), effectively reducing interbreeding and promoting the formation of new species. Occasionally, however, novel combinations of genes yield ecological advantages to hybrids, including adaptation to new ecological niches. What attributes of parental populations predict the outcome of hybridization? Answering this question is the focus of this project, and will provide new insights into the effects of climate and ecological changes on adaptation rates and species formation. The researchers also will engage in novel public informal education at the Birch Aquarium and in hands-on experiences in marine biology for 5th grade students in underserved San Diego neighborhoods. Predicting hybridization outcomes requires an understanding of the molecular basis of hybrid phenotypes. This project will conduct genomic analyses of hybrids produced by crosses between divergent populations of the copepod Tigriopus californicus. Previous work has shown that energy production by mitochondria is frequently disrupted in hybrids. Whole genome sequencing will be used to determine genetic differences between groups of hybrid copepods with normal versus disrupted mitochondrial performance; differentiation between the groups will identify candidate genes that are potentially responsible for hybrid breakdown. Results will address: a) Does hybridization result in widespread incompatibilities across the genome, or can targeted genes be identified? b) Are the same genomic regions responsible for hybrid breakdown in different interpopulation crosses? A similar approach will be used to examine the genomic basis of improved hybrid thermal tolerance. What genetic interactions allow some hybrids to survive temperatures that are lethal to both parental populations? Is hybrid performance predictable from genetic or ecological differences between parental populations?