Phylogenetic Status and Timescale for the Diversification of Steno and Sotalia Dolphins

Abstract

Molecular data have provided many insights into cetacean evolution but some unsettled issues still remain. We estimated the topology and timing of cetacean evolutionary relationships using Bayesian and maximum likelihood analyses of complete mitochondrial genomes. In order to clarify the phylogenetic placement of Sotalia and Steno within the Delphinidae, we sequenced three new delphinid mitogenomes. Our analyses support three delphinid clades: one joining Steno and Sotalia (supporting the revised subfamily Stenoninae); another placing Sousa within the Delphininae; and a third, the Globicephalinae, which includes Globicephala, Feresa, Pseudorca, Peponocephala and Grampus. We also conclude that Orcinus does not belong in the Globicephalinae, but Orcaella may be part of that subfamily. Divergence dates were estimated using the relaxed molecular clock calibrated with fossil data. We hypothesise that the timing of separation of the marine and Amazonian Sotalia species (2.3 Ma) coincided with the establishment of the modern Amazon River basin.

Molecular Identification and Historic Demography of the Marine Tucuxi (Sotalia guianensis) at the Amazon River’s Mouth by Means of Mitochondrial Control Region Gene Sequences and Implications for Conservation

“…and Stenella spp., were all inferred to have diversified in the late Pliocene and in the beginning of the Pleistocene [40], as it could occur with the different Sotalia lineages herein studied, showing that these climatic and geological changes had an overall repercussion on the marine dolphin diversification.…”

“…A stepwise (constant) Bayesian skyline variant was selected with the maximum time as the upper 95% highest posterior densities (HPD) and the trace of the root height as the treeModel.rootHeight. For S. guianensis, this analysis was carried out for the last 2.3 million years with a standard deviation of ±0.5 MYA (3.4-1.4 MYA) for the split between S. guianensis and S. fluviatilis [40].…”

“…It is noteworthy that, in spite of being a supermatrix analysis (of 15 mitochondrial and nuclear markers) using seven fossil calibration points and relaxed clock models, the divergence between the Sotalia species, in this last referred work, was based exclusively on the mtDNA cytochrome b gene. However, we preferred the estimation of Cunha et al [40] because it considered the complete mitochondrial DNA molecule (2.3 MYA). Taking this last divergence split between S. guianensis and S. fluviatilis, we found that the population of S. guianensis, from the estuary of the Amazon River, suffered a population expansion that began around 1 MYA (Bayesian skyline plot with the mean) or around 0.4 MYA (Bayesian skyline plot with median and MJN) and that practically continued until present day.…”

Whistle comparison of four delphinid species in Southeastern Brazil

“…8 (3.2 -16.6) 6.9 (2.5 -10.3) 13.9 (8.1 -26.6) 11.3 (3.6 -26.1) F1/2 10.4 6 2.9 6.9 6 1.5 14.3 6 4.3 14.8 6 4.9 9.6 (4.5 -20.3) 6.8 (3.9 -11.1) 14.6 (6.2 -33.0) 14.8 (3.5 -29.9) F3/4 11.0 6 2.9 7.2 6 1.6 13.8 6 3.9 18.8 6 6.5 11.0 (3.5 -19.4) 7.0 (3. The largest differences obtained in this study were found between whistles of species that were closest phylogenetically (Cunha et al, 2012), which highlights the fact that interspecific differences may not be exclusively attributed to phylogenetic relationships. Differences may be influenced by divergences in ecological characteristics such as adaptations to different environments.…”

KAJIAN MOLEKULER LUMBA-LUMBA HIDUNG BOTOL (Tursiops sp.) ASAL LAUT JAWA BERDASAR URUTAN GEN CYTOCHROME C OXIDASE SUB-UNIT II (COX II) (Molecular Studies of Bottlenose Dolphins (Tursiops sp.) from Java Sea by Gene Sequences of Cytochrome C Oxidase Sub-Unit II (COX II))

“…Hasil dari filogram ini sama seperti dengan jarak genetik spesies tersebut yang disajikan pada Tabel 3. Filogram yang dihasilkan pada penelitian ini juga sama dengan hasil penelitian Duchene et al (2011), Cunha et al (2011), Xiong et al (2009), Widayanti et al (2014 …”