Mitochondrial genetic structure of two populations of Uca urugayensis fails to reveal an impact of the Rio de la Plata on gene flow

Abstract

The Rio de la Plata. located between Uruguay and Argentina, generates a tremendous freshwater influx from the estuary into the coastal sea. It is thus suggested to constitute a biogeographic barrier for many taxa exhibiting a marine planktonic larval dispersal. However, evidence for corresponding intraspecific dispersal constraint has yet to be provided. We compared mitochondrial haplotypes of ten individuals for each of two populations of Uca (Leptuca) uruguayensis north and south of the estuary to examine the potential effect of the Rio de la Plata on the species' distribution. The populations are separated by nearly 2,000 km and were collected in São Paulo State (Brazil) and Mar Chiquita (Argentina). We found no significant indication for restricted gene flow between them, based on 823 basepairs of the mitochondrial cytochrome c oxidase subunit I gene. The structure of the corresponding haplotype network and the estimated nucleotide diversities, however, suggest that the Argentinean population is genetically more diverse than the one from Brazil. In order to establish possible significant differences in haplotype distribution, further research including more populations and larger sample sizes will be necessary.

Morphological variability in populations of the fiddler crab Leptuca uruguayensis (Nobili, 1901) (Crustacea, Decapoda, Ocypodidae) from South America

“…Considering all populations of Leptuca uruguayensis occurring along its distribution without barriers for gene flux as suggested by LAURENZANO et al (2012), the intraspecific difference in the carapace width between the two populations found in the present work is remarkable. Actually, the largest male found in the present study (=19.5 mm CW) was bigger than that recorded by CRANE (1975) in the same Province of Maldonado, Uruguay.…”

“…Based on cytochrome c oxidase I gene data, LAURENZANO et al (2012) did not find any significant restriction in the gene flux between the Brazilian (São Paulo State) and Argentinean (Mar Chiquita) populations of L. uruguayensis, that are living as far as 2,000 Km, and separated by a barrier consisting of Río de La Plata.…”

Intraspecific variation in carapace morphology among fiddler crabs (Genus Uca) from the Atlantic coast of Brazil

“…maracoani distributed between Amapá (AP) and Paraná (PR). Studies on other crab species also suggest that marine populations along the southern coast of Brazil are intimately connected by gene flow (Oliveira-Neto et al 2007, Laurenzano et al 2012. However, other brachyuran species along this coast may exhibit strong genetic differentiation in patterns that indicate isolation-by-distance over about the same length of coastline (Ituarte et al 2012).…”

Genetic homogeneity in the commercial pink shrimp Farfantepenaeus paulensis revealed by COI barcoding gene

“…In South America, other studies using COI gene with different groups of decapods have found no structuration among different localities: Laurenzano et al (2012), with fiddler crab Uca uruguayensis (Nobili, 1901); Rossi and Mantelatto (2013), with estuarine shrimp Macrobrachium olfersii (Wiegmann, 1836); Wieman et al (2013), with Uca maracoani (Latreille, 1802e1803); and Laurenzano et al (2013), with Uca rapax, Smith 1870. However, when analyzing the population structure of F. paulensis using allozymes, Gusmão et al (2005) found that the studied populations were genetically structured in two different stocks (one from South and other from Southeast Brazil).…”