Unexpected diversity in the catfish Pseudancistrus brevispinis reveals dispersal routes in a Neotropical center of endemism: the Guyanas Region

Abstract

Neotropical freshwater fishes have reached an unrivalled diversity, organized into several areas of endemism, yet the underlying processes are still largely unknown. The topographical and ecological characteristics of the Guyanas Region make it an ideal area of endemism in which to investigate the forces that have shaped this great diversity. This region is thought to be inhabited by species descending from Amazonian ancestors, which would have used two documented routes that, however, hardly explain the entrance of species adapted to running waters. Here, we investigate the evolutionary history of Pseudancistrus brevispinis, a catfish endemic to this region and exclusively found in running waters, thus making it an ideal model for investigating colonization routes and dispersal in such habitats. Our analyses, based on mitochondrial and nuclear markers, revealed an unexpected diversity consisting of six monophyletic lineages within P. brevispinis, showing a disjoint distribution pattern. The lineages endemic to Guyanas coastal rivers form a monophyletic group that originated via an ancestral colonization event from the Amazon basin. Evidence given favours a colonization pathway through river capture between an Amazonian tributary and the Upper Maroni River. Population genetic analyses of the most widespread species indicate that subsequent dispersal among Guyanas coastal rivers occurred principally by temporary connections between adjacent rivers during periods of lower sea level, yet instances of dispersal via interbasin river captures are not excluded. During high sea level intervals, the isolated populations would have diverged leading to the observed allopatric species. This evolutionary process is named the sea level fluctuation (SLF) hypothesis of diversification.

Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units

“…Biotic dispersal has been a major factor in historical hybridization and diversity generation in Amazonian rivers. This is a consequence of the importance of neotectonic activity and resulting rearrangements in the drainage network as diversity-generating factors, both in freshwater fishes in general (Burridge et al, 2006Cardoso, Montoya-Burgos, 2009;Waters et al, 2007) and neotropical fishes in particular Lima, Ribeiro, 2011;Ribeiro et al, 2013;Roxo et al, 2014;Tagliacollo et al, 2015). Those observations and ensuing conclusions prompt a reevaluation of the assumption that vicariant and dispersalist events in their pure form are the best explanation for the diversification of the neotropical fish fauna.…”

A recent transposition of river involving Paraná and São Francisco basins: Effects on the genetic variability and structure of the neotropical fishParauchenipterus galeatus(Siluriformes, Auchenipteridae)

“…The control region of the mitochondrial DNA (D-loop) has been featured in population studies due to its high mutation rate (Galtier et al 2009), which is up to 100 times faster when compared to nuclear DNA. Hence, this is the main mitochondrial DNA sequence used for population studies and for phylogenetically close species, including several examples in fish (Faber and Stepien 1977;Meyer 1994;Suárez et al 2001;Prioli et al 2002;Avise 2004;Li and Gui 2007;Cardoso and Montoya-Burgos 2009. This study aimed to characterize, through the sequencing of the control region of the mitochondrial DNA, three populations of P. galeatus from the Paraná, São Francisco, and Piumhi River basins and, through this information, investigate the process of divergence between these populations, including the possible effect of anthropic action on this species of fish present in a transposition river region.…”

Determinants of fish assemblage structure in Mount Itoupé mountain streams (French Guiana)

“…As most fish cannot cross dry land and/or salt water, each basin can be considered as a biogeographic island and hence only rarely share individual fish with its counterparts (Hugueny, 1989;Oberdorff et al, 2011). Inter-basin colonization is therefore a rare event due to tributary captures from one basin to another or variations in sea water levels (Hubert and Renno, 2006;Cardoso and Montoya-Burgos, 2009;de Me´rona et al, 2012). The fish assemblage of each basin is hence dependent on equilibrium between immigration/emigration and speciation/extinction events (MacArthur and Wilson, 1967;Oberdorff et al, 2011).…”