The Biology of Polymorphic Melanic Side-Spotting Patterns in Poeciliid Fishes

Melanin-based color patterns are an emerging model for studying molecular and evolutionary mechanisms driving phenotypic correlations. Extensive literature exists on their correlated traits in the family Poeciliidae, indicating that these fishes tractable models. We review biology of polymorphic melanic side-spotting characterized by macromelanophores forming irregular spotted across fishes’ flanks. These present genera Gambusia, Limia, Phalloceros, Poecilia , Xiphophorus . Their presence is controlled dominant genes autosomes or sex chromosomes. Variation expression under polygenic control; however, genes’ identities still largely unknown. In some Gambusia holbrooki latipinna dependent low temperature exposure, but underlying Spotted fish develop melanoma rare cases a well-developed research. Little known about other physiological correlates except G. males exhibit higher basal cortisol levels than unspotted metabolic rate does not differ between morphs species. Behavioral differences widespread, specific to population, species, social context. appear be more dominant. Juvenile have lower behavioral flexibility, X. variatus greater stress resistance. Findings conflict whether sexual behavior selection females. Melanic uncommon (<30%) populations, although extreme high-frequency populations exist. This frequency surprising genes, variety selective pressures influence both traits. reproductive life history larger survival when uncommon, remain strong advantage during predation. Predators prefer attack consume morphs; this preference disappears common, negative frequency-dependent selection. preferred socially turbid conditions, environmental factors shape correlations morph fitness been studied. Finally, we questions future studies patterns.