Abstract
Abstract The coastal basins in Northeastern Brazil used in this study make up two different ecoregions for freshwater fishes (Amazonas estuary and coastal drainages, and Parnaiba) and two areas of endemism for Characiformes (Maranhão and Parnaíba), and exhibits a diversified yet poorly explored freshwater fish fauna. The population structure and biogeography of two migratory freshwater fish species that are commercially exploited from Maranhão and Parnaíba regions were herein analyzed. Molecular sequence data and statistical analyses were used to estimate haplotypes networks and lineage divergence times and correlated with hydrographic history of drainage and paleodrainages of the region. A total of 171 sequences was produced for both species, Schizodon dissimilis (coI, n = 70) and Prochilodus lacustris (D-loop, n = 101). All analyses identified the presence of three genetically delimited groups of S. dissimilis and six groups of P. lacustris. The lineage time analyses indicate diversification among these species within the past 1 million year. The results indicate the influence of geodispersal in the formation of the ichthyofauna in the studied area through headwater stream capture events and reticulated connections between the mouths of rivers along the coastal plain due to eustatic sea level fluctuations.
Highlights
Studies using phylogenetic and comparative approaches to understand the biodiversity and biogeography of South American fishes are many and varied (e.g. Sivasundar et al, 2001; Beheregaray et al, 2002; Farias, Hrbek, 2008; Albert et al, 2011a; Pereira et al, 2013)
Seventy individuals of Schizodon dissimilis and 101 individuals of Prochilodus lacustris were sampled from 14 localities across the Maranhão coastal basins including the Parnaíba, Itapecuru, Mearim, Turiaçu, and Tocantins basins (Tab. 1)
The Cytochrome oxidase subunit I gene was amplified by polymerase chain reaction (PCR) for S. dissimilis samples using the primers FishF1 and FishR1 (Ward et al, 2005)
Summary
Studies using phylogenetic and comparative approaches to understand the biodiversity and biogeography of South American fishes are many and varied (e.g. Sivasundar et al, 2001; Beheregaray et al, 2002; Farias, Hrbek, 2008; Albert et al, 2011a; Pereira et al, 2013). Sivasundar et al, 2001; Beheregaray et al, 2002; Farias, Hrbek, 2008; Albert et al, 2011a; Pereira et al, 2013) Most of these studies focus on hypotheses to explain the origin, richness, and distribution patterns of fishes in fauna of the Amazon and adjacent river basins of northern South America. The Maranhão region of Northeastern Brazil exhibits a diverse and poorly explored freshwater fish fauna and is represented in different configurations in studies based in the distribution patterns of the species This area has been treated as representing two different ecoregions (Abell et al, 2008; the Amazonas estuary and coastal drainages, and Parnaiba), and alternatively two distinct areas of endemism (to Hubert, Renno, 2006; Maranhão and Parnaíba), differentiated by the size of the areas. Through the use of haplotypes network, lineage divergence times, and statistical analyses using molecular data, and by comparing these biological data with available geological information from the region, we identify the most important paleogeographic events that promoted the differentiation of these species
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