Population differentiation in the franciscana (Pontoporia blainvillei) from two geographic locations in Brazil as determined from mitochondrial DNA control region sequences

Abstract

The franciscana, Pontoporia blainvillei, is a dolphin that experiences extensive incidental mortality in fisheries throughout its restricted distribution and is perhaps the most exploited species along the Atlantic coast of South America. However, the basic information required for effective conservation of this species is lacking. To understand the population structure of this platanistoid dolphin, we sequenced 418 base pairs (bp) of the control region and 68 bp of the adjacent pro-tRNA gene of the mtDNA from 20 franciscana that were captured incidentally by gill-net fisheries of Rio Grande do Sul and Rio de Janeiro, Brazil. Of 11 haplotypes found, 5 were exclusive to franciscana from Rio Grande do Sul and 6 were found only in franciscana from Rio de Janeiro and no haplotypes were shared between locations. Reconstruction of the phylogenetic relationships among the haplotypes through a maximum-likelihood analysis of sequences revealed two distinct lineages that were consistent with the geographic sampling locations. Analysis of molecular variance also showed the population structure (phiST = 0.403, p < 0.0001). Furthermore, the estimate of nucleotide diversity for the northern population (0.38 ± 0.13%) was significantly lower than for the southern population (1.01 ± 0.30%). The genetic evidence indicated that at least two populations of franciscana exist.

Morphometric relationships of franciscana dolphin, Pontoporia blainvillei (Cetacea), off Rio Grande do Sul coast, southern Brazil

“…This suggested a model based upon a single sample of both sexes, with its increased precision due to larger sample size, may be preferable. Several morphometric and genetic studies (Pinedo, 1991(Pinedo, , 1995Secchi et al, 1998Secchi et al, , 2003aOtt et al, 2002;Ramos et al, 2002;Lázaro et al, 2004;Barreto and Rosas, 2006) have established the existence of three franciscana morphotypes/genotypes: one found in FMA I (Rio de Janeiro and Espírito Santo states, Brazil); a second one in FMA II (from São Paulo to Santa Catarina states, Brazil) and the third in FMA III and IV (from Rio Grande do Sul state, Brazil down to Buenos Aires Province, Argentina). Animals inhabiting FMA I are smaller than animals from FMA III and IV but larger than those from FMA II.…”

Incidental mortality of franciscana (<i>Pontoporia blainvillei</i>) in the artisanal fishery of Praia Grande, São Paulo State, Brazil

“…Pinedo (1991) Secchi et al (1998) examined mitochondrial DNA from individuals of these two forms and also found significant differences between them. Both studies suggested that the two populations should be treated as separate management units.…”

Report of the Fourth Workshop for the Coordinated Research and Conservation of the Franciscana Dolphin (<i>Pontoporia blainvillei</i>) in the Western South Altantic

“…The results were compared with those published by Secchi et al (1998), which included animals from Rio Grande do Sul (GS 9 and 10) and Rio de Janeiro (GS 3). Lázaro suggested that franciscanas from Rio Grande do Sul, Uruguay and Argentina may belong to a single large genetic population.…”

“…She also presented the results of a comparative analysis of mtDNA control region sequences between these animals and those from Rio Grande do Sul and Rio de Janeiro analysed by Secchi et al (1998). The results indicated that individuals from Paraná were more similar to those of Rio Grande do Sul than to those of Rio de Janeiro and that the population off Rio de Janeiro may be isolated.…”