The evolutionary history of the goby Elacatinus puncticulatus in the tropical eastern pacific: Effects of habitat discontinuities and local environmental variability.

Habitat discontinuities, temperature gradients, upwelling systems, and ocean currents, gyres and fronts, can affect distributions of species with narrow environmental tolerance or motility and influence the dispersal of pelagic larvae, with effects ranging from the isolation of adjacent populations to connections between them. The coast of the Tropical Eastern Pacific (TEP) is a highly dynamic environment, with various large gyres and upwelling systems, alternating currents and large rocky-habitat discontinuities, which may greatly influence the genetic connectivity of populations in different parts of the coast. Elacatinus puncticulatus is a cryptic, shallow-living goby that is distributed along the continental shore of virtually the entire TEP, which makes it a good model for testing the influence of these environmental characteristics in the molecular evolution of widespread species in this region. A multilocus phylogeny was used to evaluate the influence of habitat gaps, and oceanographic processes in the evolutionary history of E. puncticulatus throughout its geographical range in the TEP. Two well-supported allopatric clades (one with two allopatric subclades) were recovered, the geographic distribution of which does not correspond to any previously proposed major biogeographic provinces. These populations show strong genetic structure and substantial genetic distances between clades and sub-clades (cytb 0.8-7.3%), with divergence times between them ranging from 0.53 to 4.88 Mya, and recent population expansions dated at 170-130 Kya. The ancestral area of all populations appears to be the Gulf of Panama, while several isolation events have formed the phylogeographic patterns evident in this species. Local and regional oceanographic processes as well as habitat discontinuities have shaped the distribution patterns of the genetic lineages along the continental TEP. Large genetic distances, high genetic differentiation, and the results of species-tree and phylogenetic analyses indicate that E. puncticulatus comprises a complex of three allopatric species with an unusual geographic arrangement.