Genomic impact of transition to asexuality in hybrids

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Genome content and organization are extremely dynamic across animals and deciphering the mechanisms underlying this variation is critical to understand evolution and how biodiversity is generated. Sexual reproduction is one of the most beneficial forces acting on animal genome evolution, but some animals nevertheless reproduce asexually. Asexual organisms do not benefit from the positive impact of sexual reproduction and are thus expected to accumulate deleterious mutations and eventually go extinct. My students and I will examine two species of Canadian fish, the mummichog (Fundulus heteroclitus) and the Banded Killifish (Fundulus diaphanus) and their sexually and asexually reproducing hybrids. We will first determine whether their asexual hybrids are temporarilly stable by comparing freshly collected individuals to samples that were collected over two decades ago. We will then examine the genomes of sexual and asexual hybrids to investigate whether and how their genomes differ compared to the mummichog and the Banded Killifish. Finally, we will determine whether asexual hybrids accumulate more deleterious mutations compared to sexually reproducing hybrids and parental species. Together, these approaches will help us understand how genomes evolve, how sexual reproduction benefits organisms and why sexual reproduction is so widespread. Ten undergraduate and graduate students as well as one research assistant will be trained over the course of this research program. Publications stemming from our work will help understand how biodiversity is generated and maintained, and benefit the large community of evolutionary biologists that seeks to decipher the mechanisms underlying genome evolution.