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Inclusion of South American samples reveals new population structuring of the blacktip shark (Carcharhinus limbatus) in the western Atlantic.

Sodré D, Rodrigues-Filho LF, Souza RF, Rêgo PS, Schneider H, Sampaio I, Vallinoto M - Genet. Mol. Biol. (2012)

Bottom Line: In the present study, we analyzed a sample of adult individuals collected on the northern coast of Brazil and compared the sequences of the mitochondrial control region with those of populations already genotyped.In contrast to populations studied previously, which were represented by neonates, the pronounced allelic variability found in the South American individuals may have resulted from migrations from other populations in the region that have yet to be genotyped.These findings indicate that the C. limbatus population from northern Brazil is genetically distinct from all other populations and should be considered as a different management unit for the protection of stocks.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Genética e Biologia Molecular, Instituto de Estudos Costeiros, Universidade Federal do Pará, Bragança, PA, Brazil.

ABSTRACT
Carcharhinus limbatus has a cosmopolitan distribution and marked genetic structuring, mainly because of its philopatric behavior. However, analysis of this structuring has not previously included South American populations. In the present study, we analyzed a sample of adult individuals collected on the northern coast of Brazil and compared the sequences of the mitochondrial control region with those of populations already genotyped. Relatively high haplotype diversity (12 haplotypes, genetic diversity of 0.796) was observed, similar to that in other populations but with a much larger number of private alleles. In contrast to populations studied previously, which were represented by neonates, the pronounced allelic variability found in the South American individuals may have resulted from migrations from other populations in the region that have yet to be genotyped. This population was also genetically distinct from the other Atlantic populations (F(st) > 0.8), probably because of female philopatry, and apparently separated from the northwestern Atlantic group 1.39 million years ago. These findings indicate that the C. limbatus population from northern Brazil is genetically distinct from all other populations and should be considered as a different management unit for the protection of stocks.

No MeSH data available.


Mismatch distribution of all populations (A), eastern Atlantic populations (B) and Brazilian samples (C). The solid line represents the curve expected (Exp) based on the expansion model. Obs – observed.
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f2-gmb-35-752: Mismatch distribution of all populations (A), eastern Atlantic populations (B) and Brazilian samples (C). The solid line represents the curve expected (Exp) based on the expansion model. Obs – observed.

Mentions: A plot of the mismatch distribution that included all of the samples genotyped worldwide (Keeney et al., 2003, 2005; Keeney and Heist, 2006) and the Brazilian samples resulted in a multimodal curve (Figure 2A) that could be accounted for by structuring of the different groups of haplotypes. However, when only the western Atlantic samples were included, the curve was bimodal (Figure 2B), indicating the existence of two groups of haplotypes that corresponded to the populations genotyped by Keeney et al. (2003, 2005) and the Brazilian samples, respectively. This finding further emphasized the differentiation of these two groups.


Inclusion of South American samples reveals new population structuring of the blacktip shark (Carcharhinus limbatus) in the western Atlantic.

Sodré D, Rodrigues-Filho LF, Souza RF, Rêgo PS, Schneider H, Sampaio I, Vallinoto M - Genet. Mol. Biol. (2012)

Mismatch distribution of all populations (A), eastern Atlantic populations (B) and Brazilian samples (C). The solid line represents the curve expected (Exp) based on the expansion model. Obs – observed.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3526082&req=5

f2-gmb-35-752: Mismatch distribution of all populations (A), eastern Atlantic populations (B) and Brazilian samples (C). The solid line represents the curve expected (Exp) based on the expansion model. Obs – observed.
Mentions: A plot of the mismatch distribution that included all of the samples genotyped worldwide (Keeney et al., 2003, 2005; Keeney and Heist, 2006) and the Brazilian samples resulted in a multimodal curve (Figure 2A) that could be accounted for by structuring of the different groups of haplotypes. However, when only the western Atlantic samples were included, the curve was bimodal (Figure 2B), indicating the existence of two groups of haplotypes that corresponded to the populations genotyped by Keeney et al. (2003, 2005) and the Brazilian samples, respectively. This finding further emphasized the differentiation of these two groups.

Bottom Line: In the present study, we analyzed a sample of adult individuals collected on the northern coast of Brazil and compared the sequences of the mitochondrial control region with those of populations already genotyped.In contrast to populations studied previously, which were represented by neonates, the pronounced allelic variability found in the South American individuals may have resulted from migrations from other populations in the region that have yet to be genotyped.These findings indicate that the C. limbatus population from northern Brazil is genetically distinct from all other populations and should be considered as a different management unit for the protection of stocks.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Genética e Biologia Molecular, Instituto de Estudos Costeiros, Universidade Federal do Pará, Bragança, PA, Brazil.

ABSTRACT
Carcharhinus limbatus has a cosmopolitan distribution and marked genetic structuring, mainly because of its philopatric behavior. However, analysis of this structuring has not previously included South American populations. In the present study, we analyzed a sample of adult individuals collected on the northern coast of Brazil and compared the sequences of the mitochondrial control region with those of populations already genotyped. Relatively high haplotype diversity (12 haplotypes, genetic diversity of 0.796) was observed, similar to that in other populations but with a much larger number of private alleles. In contrast to populations studied previously, which were represented by neonates, the pronounced allelic variability found in the South American individuals may have resulted from migrations from other populations in the region that have yet to be genotyped. This population was also genetically distinct from the other Atlantic populations (F(st) > 0.8), probably because of female philopatry, and apparently separated from the northwestern Atlantic group 1.39 million years ago. These findings indicate that the C. limbatus population from northern Brazil is genetically distinct from all other populations and should be considered as a different management unit for the protection of stocks.

No MeSH data available.