Fine-scale genetic structure patterns in two freshwater fish species, Geophagus brasiliensis (Osteichthyes, Cichlidae) and Astyanax altiparanae (Osteichthyes, Characidae) throughout a Neotropical stream

Abstract

ABSTRACT. Streams are very important environments for Neotropical freshwater fish fauna, and possess a high number of species. These small drainages are also highlighted by their intrinsic biological and physicochemical features; however, knowledge on the genetic distribution of fish in these drainages is limited. Therefore, in the present study, RAPD (random amplified polymorphic DNA) and microsatellite markers were used to analyze population differentiation and gene flow of Astyanax altiparanae and Geophagus brasiliensis from three sites (high, medium, and low) throughout the Penacho stream (about 32 km long), which is a Neotropical stream. Both markers revealed higher levels of genetic diversity levels for A. altiparanae ( P : 90.05; H S : 0.350) compared to G. brasiliensis ( P : 30.43; H S : 0.118), which may be related to the particular biology of each species. AMOVA revealed significant genetic variation among populations of each species. All pairwise Ф ST values were significant, ranging from 0.020 to 0.056 for A. altiparanae samples, and from 0.065 to 0.190 for G. brasiliensis samples. Bayesian clustering analysis corroborated these results and revealed clusters of both A. altiparanae (two based on RAPD data) and G. brasiliensis (two based on RAPD data and three on microsatellite data). Gene flow estimates showed that there were similar rates of migration among A. altiparanae samples and low rates of migration among some G. brasiliensis samples. These results suggest patterns of fine-scale genetic structure for both species in the Penacho stream. This information may enhance knowledge of Neotropical streams and may be useful for future management and conservation activities.

Molecular data reveal a complex population genetic structure for Psalidodon scabripinnis (Teleostei: Characidae) in the Atlantic Rainforest, Brazil

“…This population also presented low genetic diversity, which, according to the authors, may have been caused by overexploitation of fishing, pollution, or destruction of spawning sites. Ferreira et al . (2016 ) detected signs of bottleneck in five of six populations of Geophagus braziliensis studied, and the only population that did not present a bottleneck is the one in the least anthropized environment.…”

Polygynandry and high genetic diversity supported by kinship and population genetics from neotropical catfish ichthyoplankton

“…We analysed a dataset marked by highly polymorphic loci (up to 29 alleles/locus), a high probability of exclusion (>99%) and unrelated individuals. The sample sizes (>27 individuals/sample) analysed are equivalent to population studies on different fish species (Ashikaga et al, 2015; Ferreira et al, 2015, 2016, 2017, 2022; Ribolli et al, 2012). Likewise, the genetic diversity and structure are also similar to the records for adult populations of P. maculatus from the same river basin (Ferreira et al, 2022) and others (Ribolli et al, 2012).…”

Conservation genetic assessment of the paleback darter, Etheostoma pallididorsum, a narrowly distributed endemic in the Ouachita Highlands, Arkansas, USA

“…Studies assessing N e among freshwater species restricted to headwater systems (e.g. darters, Fluker et al, 2010; cichlids, Ferreira et al, 2016; cutthroat trout, Cook, Rahel, & Hubert, 2010; Atlantic salmon, Vähä, Erkinaro, Niemelä, & Primmer, 2008) have reported stable populations that exhibit small effective population sizes. Therefore, small N e estimates may be characteristic of headwater stream populations and should be taken as a cautionary warning that if the habitat becomes unstable, these populations are inherently vulnerable to extirpation or extinction.…”