Abstract
Teleost fish provide some of the most intriguing examples of sexually dimorphic coloration, which is often advantageous for only one of the sexes. Mapping studies demonstrated that the genetic loci underlying such color patterns are frequently in tight linkage to the sex-determining locus of a species, ensuring sex-specific expression of the corresponding trait. Several genes affecting color synthesis and pigment cell development have been previously described, but the color loci on the sex chromosomes have mostly remained elusive as yet. Here, we summarize the current knowledge about the genetics of such color loci in teleosts, mainly from studies on poeciliids and cichlids. Further studies on these color loci will certainly provide important insights into the evolution of sex chromosomes.
Highlights
The color pattern of vertebrates is generated by pigment cells, which are derived from the neural crest [44,45]
Sex chromosomes are a fascinating part of the genome, posing intriguing questions at the interface of evolution and genetics
Antagonistic color loci in close linkage to the sex-determining locus can contribute greatly to the development and divergence of sex chromosomes but are notoriously difficult to study at the molecular level due to the complex and usually repeat-rich genomic structure of the region in which they are located
Summary
Teleost fish display a spectacular diversity of color patterns, making them one of the most colorful vertebrate groups. While the coloration of females and males of well-studied species such as the zebrafish (Danio rerio) and the medaka (Oryzias latipes) is mostly similar, the sexes of many other teleost fish can be distinguished from each other by their pigmentation. When novel male- or female-beneficial loci emerge at the borders of the sex-determining region where substantial cross-over still occurs, selection favors the expansion of the non-recombining region along the sex chromosome [29]. This positive feedback loop leads to the formation of distinct evolutionary strata along the sex chromosomes that differ in their genetic divergence [29,33,34]. As sexually antagonistic genes can be linked to Y- and W-chromosomes or be present in polyfactorial systems, the study of such genes is illuminating in this group
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