The Colorful Sex Chromosomes of Teleost Fish

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.

Multiple Sex Chromosomes and Evolutionary Relationships in Amazonian Catfishes: The Outstanding Model of the Genus Harttia (Siluriformes: Loricariidae)

“…Besides, the bigger size of the neo-X chromosome in comparison with the Y and the loss of a A(n) rich region closer to the ribosomal loci in the later support this hypothesis. Among fishes, some cases of neo-XY sex chromosomes emerging from X and/or Y-autosomal translocations have been also observed [ 46 , 47 , 48 ]. Neo-sex chromosomes may not necessarily lead to the emergence of multiple sex chromosomes, as equal addition of autosomal segments to both sex chromosomes generates neo-XY or neo-ZW systems.…”

Mapping of the Sex Determining Region on Linkage Group 12 of Guppy (Poecilia reticulata)

“…Guppies were characterized with an XY sex chromosome system (Winge 1922). Coloring pattern and fin-shape polymorphism are inherited in a sex linked manner (Winge 1923; Kottler and Schartl 2018). Guppy sex chromosomes are morphologically distinct, containing a pseudo autosomal and unique Y non-recombining region.…”

Sex Chromosomes and Internal Telomeric Sequences in Dormitator latifrons (Richardson 1844) (Eleotridae: Eleotrinae): An Insight into Their Origin in the Genus

“…The presence of cytologically distinguishable sex chromosomes (CDSC) characterizes only a minority of fish, corresponding to less than 1% of Teleosts [ 48 , 49 ] and about 10% of the karyotped fish species [ 50 , 51 , 52 , 53 , 54 ], as in most of them the sex chromosomes are cryptic. CDSC largely appeared independently and at various times in different fish lineages, following distinct patterns of differentiation even in closely related species ([ 53 , 55 ] and references herein); they can be associated to male or female heterogamety, or even to multi-chromosomal sex determination [ 56 ].…”