<b>Genetic variability and evidence of founder effect in <i>Hemiodus orthonops</i> (Characiformes: Hemiodontidae) from the upper Paraná River basin, Brazil

Abstract

ABSTRACT. Hemiodus orthonops is a small fish of the Hemiodontidae family, order Characiformes, with a maximum of 25 cm standard length. Until recently, H. orthonops was an endemic species from the Paraná-Paraguay basin and it was absent from the upper Paraná River basin. Since 2008, it has started to be collected in the upper Paraná River, representing up to 10% of catches. Two population samples of H. orthonops from two localities of the upper Parana River basin (Porto Camargo and Porto Figueira) were analyzed using the allozymes electrophoresis technique. Twenty-one enzymatic loci were detected. The population sample from Porto Camargo displayed a genetic variability (He = 0.1061) higher than that from Porto Figueira (He = 0.0580) and homozygote excess in both of them. The F ST value (0.2081) indicated genetic structure. The excess of homozygotes in both samples was probably due to founder effect in the population.Keywords: Allozymes, fish, genetic distance, heterozygosity, protein polymorphism.Variabilidade genética e evidência do efeito do fundador em Hemiodus orthonops (Characiformes: Hemiodontidae) da bacia do alto rio Paraná, Brasil

Tempo and mode of allopatric divergence in the weakly electric fish Sternopygus dariensis in the Isthmus of Panama

“…An expected consequence of allopatric divergence is the accumulation of genetic differences across large portions of the species’ genome due to random drift 38,53,54 . However, allopatric divergence may also be affected by adaptive processes (e.g., local adaptation 55,56 ), which might lead to genomic islands of divergence 57,58 .…”

Demography and esterase polymorphism of brazilian populations of Zaprionus indianus (Diptera: Drosophilidae) from the Brazilian Cerrado localities

“…One of the ways to expand the knowledge about these bioinvaders is to identify the genetic structure of different populations aiming to evaluate the degree of isolation and gene flow among them as an indication of their movement along the geographical landscape. One tool for this purpose is the evaluation of genetic polymorphisms from the isoenzyme variation in populations [36][37][38][39][40] .…”

“…These enzymes show different electrophoretic mobility patterns, which indicates polymorphisms that could differ between populations and species that inhabit different environments [36][37][38][39][40] . From enzymatic polymorphisms, it is possible to study genetic population structure, detect and calculate the endogamy coefficient and verify the gene flow, natural selection and genetic drift occurrence.…”

Founder effect in tupian languages

“…Taking into consideration dispersal of small groups, we can reason that these migrations can lead to bottlenecks, and, consequently, to genetic drifts, putting, thus, genetic equilibrium at risk. Founder populations usually display a reduction in heterozygoticity, which reflects a cline in allelic richness, although reduction in allelic richness can be more expressive than reduction in heterozygoticity given that allelic reduction can affect rare alleles, which does not really contribute to heterozygoticity (BARTON & CHARLESWORTH, 1984;DLUGOSCH & PARKER, 2008;PIERCE et al, 2014;MARQUES & RENESTO, 2017).…”

“…Hemiodus orthonops, a small fish endemic from the Paraná-Paraguay basin, has recently migrated to the upper part of the Paraná River, founding new populations. Marques & Renesto (2017) analyzed the genotype of two founder populations, concluding that they both display a low mean of alleles per locus and an excess of homozygotes, which the authors take to be a reflex of founder events during the migration process.…”