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Herman A, Brandvain Y, Weagley J, Jeffery WR, Keene AC, Kono TJY, Bilandžija H, Borowsky R, Espinasa L, O'Quin K, Ornelas-García CP, Yoshizawa M, Carlson B, Maldonado E, Gross JB, Cartwright RA, Rohner N, Warren WC, McGaugh SE. The role of gene flow in rapid and repeated evolution of cave-related traits in Mexican tetra, Astyanax mexicanus. Mol Ecol 2018; 27:4397-4416. [PMID: 30252986 PMCID: PMC6261294 DOI: 10.1111/mec.14877] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 08/08/2018] [Accepted: 08/19/2018] [Indexed: 12/13/2022]
Abstract
Understanding the molecular basis of repeatedly evolved phenotypes can yield key insights into the evolutionary process. Quantifying gene flow between populations is especially important in interpreting mechanisms of repeated phenotypic evolution, and genomic analyses have revealed that admixture occurs more frequently between diverging lineages than previously thought. In this study, we resequenced 47 whole genomes of the Mexican tetra from three cave populations, two surface populations and outgroup samples. We confirmed that cave populations are polyphyletic and two Astyanax mexicanus lineages are present in our data set. The two lineages likely diverged much more recently than previous mitochondrial estimates of 5-7 mya. Divergence of cave populations from their phylogenetically closest surface population likely occurred between ~161 and 191 k generations ago. The favoured demographic model for most population pairs accounts for divergence with secondary contact and heterogeneous gene flow across the genome, and we rigorously identified gene flow among all lineages sampled. Therefore, the evolution of cave-related traits occurred more rapidly than previously thought, and trogolomorphic traits are maintained despite gene flow with surface populations. The recency of these estimated divergence events suggests that selection may drive the evolution of cave-derived traits, as opposed to disuse and drift. Finally, we show that a key trogolomorphic phenotype QTL is enriched for genomic regions with low divergence between caves, suggesting that regions important for cave phenotypes may be transferred between caves via gene flow. Our study shows that gene flow must be considered in studies of independent, repeated trait evolution.
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Affiliation(s)
- Adam Herman
- Plant and Microbial Biology, Gortner Lab, University of Minnesota, Saint Paul, Minnesota
- Department of Molecular Biology, Rudjer Boskovic Institute, Zagreb, Croatia
| | - Yaniv Brandvain
- Plant and Microbial Biology, Gortner Lab, University of Minnesota, Saint Paul, Minnesota
| | - James Weagley
- Ecology, Evolution, and Behavior, Gortner Lab, University of Minnesota, Saint Paul, Minnesota
| | - William R Jeffery
- Department of Biology, University of Maryland, College Park, Maryland
| | - Alex C Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida
| | - Thomas J Y Kono
- Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota
| | - Helena Bilandžija
- Department of Molecular Biology, Rudjer Boskovic Institute, Zagreb, Croatia
- Department of Biology, University of Maryland, College Park, Maryland
| | | | - Luis Espinasa
- School of Science, Marist College, Poughkeepsie, New York
| | - Kelly O'Quin
- Department of Biology, Centre College, Danville, Kentucky
| | - Claudia P Ornelas-García
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Coyoacán, Mexico
| | - Masato Yoshizawa
- Department of Biology, University of Hawai'i at Mānoa, Honolulu, Hawaii
| | - Brian Carlson
- Department of Biology, College of Wooster, Wooster, Ohio
| | - Ernesto Maldonado
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Mexico
| | - Joshua B Gross
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio
| | - Reed A Cartwright
- The Biodesign Institute, Arizona State University, Tempe, Arizona
- School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, Missouri
- Department of Molecular and Integrative Physiology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Wesley C Warren
- McDonnell Genome Institute, Washington University, St Louis, Missouri
| | - Suzanne E McGaugh
- Department of Molecular Biology, Rudjer Boskovic Institute, Zagreb, Croatia
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