The role of character displacement in the speciation of Central American members of the genus Poecilia (Poeciliidae)

Abstract

Fishes of the genus Poecilia are predominant inhabitants of the Central American mainland and of the Greater Antilles. The genus also occupies specific habitats on the South American continent and adjacent islands. In Central America, there is a confusing array of species, in which morphological and meristic characters show more variation within species than between species. By applying the principle of character displacement to the genus, several regularities emerge. Three species pairs (of which one has uni‐cuspid inner jaw teeth, the other has tricuspid inner teeth for each species pair) are present, amongst which six widely dispersed species may be discriminated. A species concept based on phylogenetic and taxonomic methods is defined for the genus Poecilia. The application of a peculiar mode of character displacement to two species of fish from El Salvador suggests a general mechanism that explains much of the morphological variation within the Central American members of Poecilia. This method also defines species boundaries and patterns of speciation based on ecologically derived mechanisms.

Key words:

• Poecilia
• Character displacement
• Species pairs
• Speciation