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Population Genetics of Franciscana Dolphins (Pontoporia blainvillei): Introducing a New Population from the Southern Edge of Their Distribution.

Gariboldi MC, Túnez JI, Dejean CB, Failla M, Vitullo AD, Negri MF, Cappozzo HL - PLoS ONE (2015)

Bottom Line: From the analysis of mitochondrial DNA control region sequences, 5 novel haplotypes were found, totalizing 60 haplotypes for the entire distribution range.The haplotype network did not show an apparent phylogeographical signal for the southern FMAs.The apparent increase in NC+CL+RN size would be consistent with the higher genetic variability found, since genetic diversity is generally higher in older and expanding populations.

View Article: PubMed Central - PubMed

Affiliation: Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.

ABSTRACT
Due to anthropogenic factors, the franciscana dolphin, Pontoporia blainvillei, is the most threatened small cetacean on the Atlantic coast of South America. Four Franciscana Management Areas have been proposed: Espiritu Santo to Rio de Janeiro (FMA I), São Paulo to Santa Catarina (FMA II), Rio Grande do Sul to Uruguay (FMA III), and Argentina (FMA IV). Further genetic studies distinguished additional populations within these FMAs. We analyzed the population structure, phylogeography, and demographic history in the southernmost portion of the species range. From the analysis of mitochondrial DNA control region sequences, 5 novel haplotypes were found, totalizing 60 haplotypes for the entire distribution range. The haplotype network did not show an apparent phylogeographical signal for the southern FMAs. Two populations were identified: Monte Hermoso (MH) and Necochea (NC)+Claromecó (CL)+Río Negro (RN). The low levels of genetic variability, the relative constant size over time, and the low levels of gene flow may indicate that MH has been colonized by a few maternal lineages and became isolated from geographically close populations. The apparent increase in NC+CL+RN size would be consistent with the higher genetic variability found, since genetic diversity is generally higher in older and expanding populations. Additionally, RN may have experienced a recent split from CL and NC; current high levels of gene flow may be occurring between the latter ones. FMA IV would comprise four franciscana dolphin populations: Samborombón West+Samborombón South, Cabo San Antonio+Buenos Aires East, NC+CL+Buenos Aires Southwest+RN and MH. Results achieved in this study need to be taken into account in order to ensure the long-term survival of the species.

No MeSH data available.


Demographic history based on the mtDNA control region sequences from populations NC+CL+NC and MH.A) Mismatch distributions. Observed and expected distributions are shown with bars and lines, respectively. B) Bayesian skyline plots. The black line is the median estimated and the blue lines show the 95% highest posterior density (HPD) intervals. NC: Necochea; CL: Claromecó; RN: Río Negro; MH: Monte Hermoso.
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pone.0132854.g003: Demographic history based on the mtDNA control region sequences from populations NC+CL+NC and MH.A) Mismatch distributions. Observed and expected distributions are shown with bars and lines, respectively. B) Bayesian skyline plots. The black line is the median estimated and the blue lines show the 95% highest posterior density (HPD) intervals. NC: Necochea; CL: Claromecó; RN: Río Negro; MH: Monte Hermoso.

Mentions: When demographic history was analyzed based on the mismatch distribution, populations differed among their demographic histories. Using goodness of fit tests based on the r, the adequacy of the sudden expansion model could not be rejected for NC+CL+RN (P = 0.15 for NC+CL+RN; P = 0.02 for MH). Furthermore, the distribution obtained for this population showed a bimodal graph, suggestive of two expansions at different times, with a dominant right wave crest translated to an estimated time since expansion of approximately 631,500 years before present (ybp) (Fig 3). In contrast, as expected under a model of relative constant population size, MH showed a multimodal mismatch distribution (Fig 3). Also, for both populations non-departure from the hypothesis of neutrality was observed (Table 1).


Population Genetics of Franciscana Dolphins (Pontoporia blainvillei): Introducing a New Population from the Southern Edge of Their Distribution.

Gariboldi MC, Túnez JI, Dejean CB, Failla M, Vitullo AD, Negri MF, Cappozzo HL - PLoS ONE (2015)

Demographic history based on the mtDNA control region sequences from populations NC+CL+NC and MH.A) Mismatch distributions. Observed and expected distributions are shown with bars and lines, respectively. B) Bayesian skyline plots. The black line is the median estimated and the blue lines show the 95% highest posterior density (HPD) intervals. NC: Necochea; CL: Claromecó; RN: Río Negro; MH: Monte Hermoso.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519281&req=5

pone.0132854.g003: Demographic history based on the mtDNA control region sequences from populations NC+CL+NC and MH.A) Mismatch distributions. Observed and expected distributions are shown with bars and lines, respectively. B) Bayesian skyline plots. The black line is the median estimated and the blue lines show the 95% highest posterior density (HPD) intervals. NC: Necochea; CL: Claromecó; RN: Río Negro; MH: Monte Hermoso.
Mentions: When demographic history was analyzed based on the mismatch distribution, populations differed among their demographic histories. Using goodness of fit tests based on the r, the adequacy of the sudden expansion model could not be rejected for NC+CL+RN (P = 0.15 for NC+CL+RN; P = 0.02 for MH). Furthermore, the distribution obtained for this population showed a bimodal graph, suggestive of two expansions at different times, with a dominant right wave crest translated to an estimated time since expansion of approximately 631,500 years before present (ybp) (Fig 3). In contrast, as expected under a model of relative constant population size, MH showed a multimodal mismatch distribution (Fig 3). Also, for both populations non-departure from the hypothesis of neutrality was observed (Table 1).

Bottom Line: From the analysis of mitochondrial DNA control region sequences, 5 novel haplotypes were found, totalizing 60 haplotypes for the entire distribution range.The haplotype network did not show an apparent phylogeographical signal for the southern FMAs.The apparent increase in NC+CL+RN size would be consistent with the higher genetic variability found, since genetic diversity is generally higher in older and expanding populations.

View Article: PubMed Central - PubMed

Affiliation: Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.

ABSTRACT
Due to anthropogenic factors, the franciscana dolphin, Pontoporia blainvillei, is the most threatened small cetacean on the Atlantic coast of South America. Four Franciscana Management Areas have been proposed: Espiritu Santo to Rio de Janeiro (FMA I), São Paulo to Santa Catarina (FMA II), Rio Grande do Sul to Uruguay (FMA III), and Argentina (FMA IV). Further genetic studies distinguished additional populations within these FMAs. We analyzed the population structure, phylogeography, and demographic history in the southernmost portion of the species range. From the analysis of mitochondrial DNA control region sequences, 5 novel haplotypes were found, totalizing 60 haplotypes for the entire distribution range. The haplotype network did not show an apparent phylogeographical signal for the southern FMAs. Two populations were identified: Monte Hermoso (MH) and Necochea (NC)+Claromecó (CL)+Río Negro (RN). The low levels of genetic variability, the relative constant size over time, and the low levels of gene flow may indicate that MH has been colonized by a few maternal lineages and became isolated from geographically close populations. The apparent increase in NC+CL+RN size would be consistent with the higher genetic variability found, since genetic diversity is generally higher in older and expanding populations. Additionally, RN may have experienced a recent split from CL and NC; current high levels of gene flow may be occurring between the latter ones. FMA IV would comprise four franciscana dolphin populations: Samborombón West+Samborombón South, Cabo San Antonio+Buenos Aires East, NC+CL+Buenos Aires Southwest+RN and MH. Results achieved in this study need to be taken into account in order to ensure the long-term survival of the species.

No MeSH data available.