The genetic architecture of phenotypic diversity in the Betta fish ( <i>Betta splendens</i> )

Abstract

The Betta fish displays a remarkable variety of phenotypes selected during domestication. However, the genetic basis underlying these traits remains largely unexplored. Here, we report a high-quality genome assembly and resequencing of 727 individuals representing diverse morphotypes of the Betta fish. We show that current breeds have a complex domestication history with extensive introgression with wild species. Using a genome-wide association study, we identify the genetic basis of multiple traits, including coloration patterns, the "Dumbo" phenotype with pectoral fin outgrowth, extraordinary enlargement of body size that we map to a major locus on chromosome 8, the sex determination locus that we map to <i>dmrt1</i>, and the long-fin phenotype that maps to the locus containing <i>kcnj15</i>. We also identify a polygenic signal related to aggression, involving multiple neural system-related genes such as <i>esyt2</i>, <i>apbb2</i>, and <i>pank2</i>. Our study provides a resource for developing the Betta fish as a genetic model for morphological and behavioral research in vertebrates.