Genomic basis of Y‐linked dwarfism in cichlids pursuing alternative reproductive tactics

Abstract

Sex determination is extremely diverse across eukaryotes and can be controlled environmentally or genetically (Bachtrog et al., 2014).In most organisms with genetic control, the sex-determining locus is carried on a sex chromosome. Highly differentiated (i.e., heteromorphic) sex chromosome pairs, such as the XY chromosome pair in mammals and ZW chromosome pair in birds, have repeatedly evolved across the tree of life (Bachtrog et al., 2014). The first step in the evolution of sex chromosomes from autosomes in species with separate

Y-Linked Copy Number Polymorphism of Target of Rapamycin Is Associated with Sexual Size Dimorphism in Seed Beetles

“…Recombination is a key mechanism generating and maintaining allelic diversity across loci. Finding substantial diversity in the absence of recombination is therefore unexpected, but echoes similar recent findings in Y-polymorphic fish species ( Sandkam et al 2021 ; Singh et al 2023 ), including Xiphophorus where CNV in Y linked melanocortin 4 receptor gene is associated with male limited body size polymorphism ( Lampert et al 2010 ). Genetic variation should be rapidly fixed by selection and drift on the Y chromosome.…”

“…Y linked genes show typically testis specific expression, for example ( Skaletsky et al 2003 ; Hughes et al 2012 ; Soh et al 2014 ; Peichel et al 2020 ), which suggests they are associated with male primary reproductive functions. But recently, heteromorphic Y chromosomes have also been shown to affect sexually dimorphic, nonreproductive traits in humans ( Prokop and Deschepper 2015 ), drosophila ( Nielsen et al 2023 ), fish ( Lampert et al 2010 ; Sandkam et al 2021 ; Singh et al 2023 ), and seed beetles ( Kaufmann et al 2021 ), suggesting a wider role in nonsexual traits than previously appreciated ( Cīrulis et al 2022 ).…”

“…Body size is a classic quantitative trait, and although quantitative genetic evidence suggests that even the autosomal genetic architecture of body size in C. maculatus consist of a combination of few major effect loci and many small effect loci ( Kaufmann et al 2023 ), finding that a substantial part of its architecture in males is controlled by a nonrecombining “supergene” is surprising. But, a Y-linked element has also been implicated in male body size variation in humans ( Ellis et al 2001 ) and fish ( Lampert et al 2010 ; Sandkam et al 2021 ; Singh et al 2023 ) suggesting that Y-linkage may be a common way to mitigate sexual conflict over growth across diverse taxa.…”