Riverine habitat specificity constrains dispersion in a Neotropical fish (Characidae) along Southern Brazilian drainages

Abstract

Riverine habitat specificity constrains dispersion in a Neotropical fish (Characidae) along Southern Brazilian drainages. -Zoologica Scripta, 44, 374-382. Freshwater fishes often display a marked phylogeographic structure strongly associated with historical and ecological changes in the aquatic environment. Different ecological conditions in the same river drainage may act as permeable barriers to dispersion and gene flow. Previous studies recognized two discrete spatial components for the ichthyofauna in the freshwater coastal drainages of southern Brazil: the lowland fish fauna in the lagoons and the fish fauna of the rivers flowing in the valleys. In order to test if the coastal lagoons may limit the dispersion of a riverine species, we describe the phylogeographic structure among populations of Cyanocharax itaimbe, a species endemic to this region. We analysed 55 specimens characterized for two mitochondrial and one nuclear genes. Sequences were analysed using gene trees and species tree approaches, together with standard population genetics methods. Molecular analyses indicated three evolutionary groups which diverged from each other between an estimated 1,600,000 and 450,000 years before the present. However, two currently isolated river systems share the same evolutionary clade, whereas a single drainage contains two different lineages. Our results indicate strong genetic structure among populations along with generally conserved morphology. The strong genetic structure among populations living in the same drainage system may be explained by ecological differences between lagoons and rivers (or palaeochannels) that act as barriers to dispersion. Corresponding author: Alice Hirschmann, Programa de P os-Graduac ßão em Biologia Animal, Av. Bento Gonc ßalves, 9500, Universidade Federal do Rio Grande do Sul,

Ontogenetic changes in mouth morphology triggers conflicting hypotheses of relationships in characid fishes (Ostariophysi: Characiformes)

“…Considering that B. lethostigmus and D. itaimbe occur in the same drainages, are syntopic, and share a similar life history, the different phylogeographic pattern found for both species is striking. While D. itaimbe shows a strong genetic structure with well-defined mtDNA clades (Hirschmann et al, 2015), B. lethostigmus showed no genealogical structure, and only a very weak genetic structure based on mtDNA data. Such phylogeographic difference between these species may be explained by three different scenarios, or a combination of them: (1) Different mtDNA evolutionary rates between the two species; (2) Different colonization times of the two species in these drainages; and (3) Gene flow among B. lethostigmus populations through paleaodrainages hampering population structure.…”

“…The mtDNA data set was analysed assuming an evolutionary rate of 0.01/site/Myr (Bermingham et al, 1997;Reeves, Bermingham, 2006;Ornelas-García et al, 2008) and a strict clock model, which is a generally well justified for analysis within a species or among a few closely related species (Li, Drummond, 2011). To compare the evolutionary history of B. lethostigmus to that of a sympatric species, we estimated coalescence times and population sizes for D. itaimbe based on sequences obtained from GenBank (KP399679 to KP399733; KP406648 to KP406702; Hirschmann et al, 2015). Based on the Bayesian Information Criterion in PartitionFinder (Lanfear et al, 2012) we assumed the HKY+I substitution model for COI and ND2.…”

“…1), an area of high endemism of fish species because of the congruent distributional pattern among several species that are solely found among these three drainages (Malabarba, Isaia, 1992). Recently, Hirschmann et al (2015) showed that Diapoma itaimbe (Malabarba & Weitzman, 2003), another member of Stevardiinae, has a very strong genetic structure among these drainages, and that the rio Araranguá population is the most distinct among them. Bryconamericus lethostigmus and D. itaimbe are sympatric and share the same habitats with clear and cold waters over rocky substrates, leading to the hypothesis that B. lethostigmus may also have strong population structure among these drainages.…”

“…Next, we describe and analyse the mouth shape and the origin of a single series of teeth in the premaxilla in B. lethostigmus, a species of a group characterized by the presence of two tooth series, and discuss its phylogenetic implications and possible homologies with other stevardiines. Finally, we analyse the genetic variation found in the populations of B. lethostigmus from the Tramandai-Mampituba ecoregion (Abell et al, 2008) to test if this species displays the same phylogeographic structure observed for D. itaimbe (Hirschmann et al, 2015), and if the rio Araranguá population represents a different species (Malabarba, 1998: 232).…”

New species of Scleromystax Günther, 1864 (Siluriformes: Callichthyidae) - extending the meridional distribution of genera endemic to the Atlantic Forest

“…That species was described from the rio Mampituba and rio Araranguá, in Santa Catarina State (Britto & Reis, 2005) based on a few lots. These two rivers form, along with the rio Tramandaí drainage, an area of endemism in southern Brazil, sharing a number of endemic fish species (Malabarba & Isaia, 1992;Reis & Schaefer, 1998;Hirschmann et al, 2015), and historically united in a single palaeodrainage in the area exposed with the retreat in sea level during the Last Glacial Maximum . Surprisingly, S. salmacis was not recorded from the rio Maquiné or rio Três Forquilhas in the rio Tramandaí drainage, regardless the extensive collections of fishes from rio Tramandaí drainage (e.g., see map of distributional records of Corydoras paleatus in this drainage at Malabarba et al, 2013: 65).…”