Phylogeography of the Neotropical catfish Pimelodus albicans (Siluriformes: Pimelodidae) from río de la Plata basin, South America, and conservation remarks

Abstract

Pimelodus albicans Valenciennes, 1840 (common name "moncholo" or "bagre blanco") is an endemic species of the family Pimelodidae in the río de la Plata basin. Phylogenetic approach based on cytochrome b sequences was performed to test the existence of a unique evolutionary lineage in P. albicans and to discriminate populations units or subpopulations related to a migration behavior of this taxon in the río de la Plata basin. This study included 34 samples of P. albicans of different collecting sites in the río de la Plata estuary and in the río Arrecifes belonging to the río Paraná basin. Among 614 base pairs in the cytochrome b sequence data set, 203 were variable and 120 were phylogenetically informative sites in P. albicans. A total of twenty haplotypes, nucleotide diversity ( ) = 0.032 and haplotype diversity = 0.941 were found. Tajima's test showed significant value D= -1.88 (p<0.05) rejecting the neutral mutation hypothesis for the P. albicans data set. All phylogenetic approaches showed that P. albicans included four monophyletic assemblages that were supported by high bootstrap and Bayesian posterior probability values. Minimum spanning network corroborated these groups for P. albicans haplotypes. High genetic structure was found in P. albicans by means of AMOVA analysis showing that the río Arrecifes samples constitute an isolated lineage. Moreover, the high value of genetic divergence (10%) between the río de la Plata and the río Arrecifes populations could suggest that P. albicans may be conformed by a sibling species complex. On the other hand, a degree of genetic structuring was detected among different sites of the río de la Plata. A partial isolation of the 760 site may suggest that P. albicans could migrates to different tributaries for reproduction, generating different schools of haplotypes which could mix in the río de la Plata estuary. The high nucleotide diversity found in the 765 site and the existence of gene flow with the remaining collecting sites would be concordant with the outlined hypothetic scenarios of the mixing populations in the middle of the río de la Plata estuary.Pimelodus albicans Valenciennes, 1840 (popularmente conhecida como moncholo ou bagre branco) é uma espécie endêmica da família Pimelodidae na bacia do rio da Prata. Estudos filogeográficos baseados nas seqüências do citocromo b mitocondrial foram realizados para testar a existência de uma única linhagem evolutiva in P. albicans e para discriminar unidades populacionais relacionadas ao comportamento migratório desse táxon na bacia do rio da Prata. Um total de 34 amostras de P. albicans provenientes de diferentes lugares de coleta no estuário do rio da Prata e rio Arrecifes na bacia do rio Paraná foram analisados. Entre as 614 pares de bases do citocromo b no conjunto de dados, 203 deles variaram e 120 foram sítios filogeneticamente informativos para P. albicans. No presente estudo foi encontrado um total de vinte haplótipos, diversidade de nucleotídeos ( ) = 0,032 e diversidade de haplótipos = 0,941. O teste de Tajima...

Molecular and karyotypic phylogeography in the NeotropicalHoplias malabaricus(Erythrinidae) fish in eastern Brazil

“…In the highly migratory species, Prochilodus spp., substitution rates of ATPase 6,8 range from 0·8 to 2·5% (Sivasundar et al, 2001), suggesting haplotypes in H. malabaricus are among the most divergent in the Neotropical region. The present study is the first to indicate such a deep molecular divergence within the same karyomorph, although deep cytochrome b divergences were also observed among populations of the catfish Pimelodus albicans (Valenciennes) in the River Plate basin (Vergara et al, 2008).…”

Comparative application of direct sequencing, PCR-RFLP, and cytogenetic markers in the genetic characterization of Pimelodus (Siluriformes: Pimelodidae) species: Possible implications for fish conservation

“…The majority of molecular studies available for the genus Pimelodus use isozymes (Renesto et al, 2000) and random amplification of polymorphic DNA (RAPD) markers (Almeida et al, 2003) to differentiate distinct species within this genus. Only recently, P. albicans was the focus of studies involving the sequencing of mitochondrial genes, which revealed a remarkable haplotype diversity among the samples analyzed and confirmed the occurrence of a species complex (Vergara et al, 2008).…”

“…Among pimelodids, Pimelodus is the most genetically studied genus (Renesto et al, 2000;. Because several populations present quite similar morphological traits but distinctive genetic features, some species are commonly known as species complexes, like P. maculatus (Almeida et al, 2003) and P. albicans (Vergara et al, 2008).…”

“…Only a few studies have attempted to define the evolutionary relationships among species of a single genus (Vergara et al, 2008). Cytogenetics and molecular genetics proved to be efficient in the characterization and differentiation of several species in fish studies.…”

Cryptic Diversity Between Two Imparfinis Species (Siluriformes, Heptapteridae) by Cytogenetic Analysis and DNA Barcoding

“…[1][2][3][4] One of the main problems related to taxonomic and systematic conflicts involving Siluriformes, and specifically Heptapteridae, resides in the fact that many of these animals present cryptic diversity, which is reflected in the numerous propositions of species complexes for the group, mainly for the very specious genera or species with a wide geographic distribution. [5][6][7] Among the Heptapteridae genera, Imparfinis has been highlighted as taxonomically problematic, accounting for 21 recognized species, 9 of which occur in Brazil. 2,[8][9][10] There have been few cytogenetic studies on this genus, and data are available for only five species: Imparfinis borodini, 11 Imparfinis mirini, 12 Imparfinis hollandi, 13 Imparfinis piperatus, 14 and Imparfinis schubarti.…”