Hybridization underlies localized trait evolution in cavefish
Authors: Suzanne McGaugh 1; Rachel Moran 1; James Jaggard 2,3; Emma Roback 1; Alexander Kenzior 4; Nicolas Rohner 4,5; Johanna Kowalko 6; Patricia Ornelas-Garcia 7; Alex Keene 8
Affiliations: 1) 1. Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN; 2) 2. Department of Biological Sciences, Florida Atlantic University, Jupiter FL; 3) 3. Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA; 4) 4. Stowers Institute for Medical Research, Kansas City, MO; 5) 5. Department of Molecular & Integrative Physiology, KU Medical Center, Kansas City, KS; 6) 6. Department of Biological Sciences, Lehigh University, Bethlehem, PA; 7) 7. Departamento de Zoología, Instituto de Biología, Universidad Autónoma de México, CP 04510, Mexico City, Mexico; 8) 8. Department of Biology, Texas A&M University, College Station, TX 77843
Keywords: Comparative genomics & genome evolution
Introgressive hybridization often drives patterns of phenotypic evolution and may play an integral role in the evolutionary processes of local adaptation and speciation. In the Mexican tetra Astyanax mexicanus, cave populations have repeatedly evolved traits including eye loss, sleep loss, and albinism. Of the 30 caves inhabited by A. mexicanus, Chica cave is unique because it contains multiple individual pools inhabited by putative hybrids between surface and cave populations, providing an opportunity to investigate the impact of hybridization on complex trait evolution. We provide evidence that hybridization between cave and surface populations may contribute to localized variation in traits associated with cave evolution, including pigmentation, eye development, and sleep. We also uncover an example of convergent evolution in a circadian clock gene in multiple cavefish lineages and burrowing mammals, suggesting a shared genetic mechanism underlying circadian disruption in subterranean vertebrates. Our results provide insight into the role of hybridization in facilitating phenotypic evolution.