Comparative ecology and historical biogeography of the genus Brachyrhaphis

Abstract

Phylogenetic systematics was used to reveal micro-evolutionary processes and macro-evolutionary patterns that have resulted in the current distribution of species of the live-bearing fish genus Brachyrhaphis. A previously constructed molecular phylogeny for the genus determined that two distinct clades, deep-bodied and slender-bodied, exist within the genus. Micro-habitat variables were measured for all extant members of the genus. Water flow differed significantly between the clades and was converted to a discrete variable and, along with elevation and micro-habitat type, mapped onto the phylogeny for the genus. The evolution of micro-habitat choice was hypothesized using these results. A detailed distribution map was constructed to unveil biogeographic patterns and was also interpreted in light of the molecular phylogeny. The phylogeny was then used to construct an area cladogram. This cladogram was compared to the one derived from paleogeography. The molecular-based area cladogram adds to the growing database required to resolve the biogeography of the Caribbean.