Comparative population genetics of Basilichthys microlepidotus (Atheriniformes: Atherinopsidae) and Trichomycterus areolatus (Siluriformes: Trichomycteridae) in north central Chile

Abstract

To describe comparative population genetic structure of the Chilean silverside Basilichthys microlepidotus and the catfish Trichomycterus areolatus, four rivers and three sites within each river were investigated by the analysis of haplotype polymorphisms of the mitochondrial Control Region. For both species, analyses revealed significant differentiation among rivers and low differences within rivers. However, the species differ in haplotype composition; individuals of B. microlepidotus shared some haplotypes in all four rivers, while individuals of T. areolatus showed a different haplotype composition in most rivers. This difference may be explained by the different ecological features of the species. Assuming that both silversides and catfish were present before the separation of the rivers, B. microlepidotus migrated after river isolation, probably using coastal water, while T. areolatus has probably never migrated between these rivers. The long times that the studied rivers have been separated should be taken into account in future conservation plans for the freshwater fish of Chile.This work was supported by Fondecyt 11060496 to DV. DV thanks also Grant PFB-23 (CONICYT, Chile) and Grant ICM P05-002. CQR thanks Master CONICYT Grant

Morphological analysis of Trichomycterus areolatus Valenciennes, 1846 from southern Chilean rivers using a truss-based system (Siluriformes, Trichomycteridae)

“…It is also possible that preexisting genetic differences among current populations can be enhanced by their isolation, resulting in a notable inter-population structuring (Esguícero and Arcifa 2010). Previous molecular studies of T. areolatus across its distribution range reveal a high level of genetic differentiation among populations within and between watersheds (Unmack et al 2009a, Quezada–Romegialli et al 2010). This high degree of genetic divergence seem to be related to geographic isolation and the subsequent low genetic flow among populations of this species, given that Chilean watersheds flow relatively straight from the east (Andean mountains) to the west (Pacific Ocean), limiting opportunities for contact despite relatively short geographical distances among populations.…”

“…The origin of morphological variation in T. areolatus remains unknown, but potential causes include local adaptation, due to the environmental variability of rivers, or geographic isolation of populations due to the physical separation between hydrographic basins (Pardo 2002). Another possible source of variation is the marked genetic structure of this species throughout its distribution range, associated with the low gene flow among drainage systems (Unmack et al 2009a; Quezada–Romegialli et al 2010). As studies undergone to date have mainly targeted northern and central regions of its range; it is unclear whether southern Chilean populations of T. areolatus exhibit similar levels of morphological variation.…”

Evaluating taxonomic homogenization of freshwater fish assemblages in Chile

“…We thus welcome further taxonomic and phylogenetic assessments to validate this issue. Indeed, recent phylogeographic studies of native Orestias, Basilichthys, Hatcheria, Trichomycterus, and Aplochiton have provided molecular evidence for increasing or decreasing the number of taxa, and such evidence is incorporated in our analyses to the extent of our knowledge (e.g., Vila 2006;Unmack et al 2009;Quezada-Romegialli et al 2010;Vila et al 2011;Véliz et al 2012;Alò et al 2013). Regarding our choice of Sørensen's index, this has been sometimes criticized as it may fail to distinguish the effects of species turnover and species richness on beta diversity (Baselga 2010, Carvalho et al 2012, Baisier et al 2012).…”

Contrasting population genetic structure of two widespread aquatic insects in the Chilean high-slope rivers

“…Quezada-Romegialli et al (2010) demonstrated a contrasting pattern of spatial genetic structure of two fish species in the same area, with one species (silverside) using the coast to cross between drainages, maintaining population connectivity and the other (a catfish) not using marine routes for dispersal thus their populations become disconnected with the separation of the river basins during the Andes uplift. This evidence showed that not all of the components of the river community have the potential to recover their habitat after perturbation, endangering the persistence and resilience of the communities.…”