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Cetartiodactyla comprises one of the most diverse mammal radiations. Currently, 23 families, 131 genera and more than 330 species are recognized. Several studies have been trying to resolve its phylogenetic relationships. The most comprehensive dated phylogenetic hypothesis available includes only 55% of the extant species, precluding a clear understanding of ecological and evolutionary patterns in Cetartiodactyla. Here, we gathered all mitochondrial genetic data available in GenBank to build a robust Cetartiodactyla calibrated phylogenetic tree using 21 fossil calibration points. We found mitogenomic data for 225 species and included other 93 species from which there was at least one mitochondrial gene available. Using a Bayesian approach, we generated a dated tree comprising 90% of the extant Cetartiodactyla species (n = 318). The major lineages showed robust support and families divergence times are congruent with the available fossil evidence and with previously published phylogenetic hypotheses. By making available a dated phylogeny with extensively sampled clades, we expect to foster future studies on the origin, tempo and mode of Cetartiodactyla diversification.

Tropical reef fishes show contrasting patterns of karyotypic diversity. Some families have a high chromosomal conservatism while others show wide variation in karyotypic macrostructure. However, the influence of life-history traits on karyotypic diversity is largely unknown. Using phylogenetic comparative methods, we assessed the effects of larval and adult species traits on chromosomal diversity rates of 280 reef species in 24 families. We employed a novel approach to account for trait variation within families as well as phylogenetic uncertainties. We found a strong negative relationship between karyotypic diversity rates and body size and depth range. These results suggest that lineages with higher dispersal potential and gene flow possess lower karyotypic diversity. Taken together, these results provide evidence that biological traits might modulate the rate of karyotypic diversity in tropical reef fishes.

Repetitive DNA varies in nature and abundance, and has had an important role in genome evolution of higher eukaryotes. In the present study we analyzed the dynamics of heterochromatic regions and telomeric sequences in three endemic South American canid species, Chrysocyon brachyurus, Lycalopex gymnocercus, and two subspecies of Cerdocyon thous by means of C-banding and fluorescence in situ hybridization (FISH) with telomeric probes. The three species revealed different banding patterns evidencing amplifications of centromeric heterochromatic and telomeric regions co-localized with telomeric sequences in L. gymnocercus and C. thous, and the presence of a heterochromatic terminal block in the Y chromosome of C. brachyurus. Additionally, an unusual heteromorphism of chromosome pair 1 was observed in the subspecies Cerdocyon thous entrerrianus. Our work emphasizes the importance of cytogenetic studies at the population level comprising the largest possible area of the geographic distribution of the species. Fil: Zurano, Juan Pablo. Parque Ecológico ‘El Puma’. Centro de Rehabilitación y Cría de Animales Silvestres; Argentina Fil: Ojeda, Diego Sebastian. Parque Ecológico ‘El Puma’. Centro de Rehabilitación y Cría de Animales Silvestres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentina Fil: Bidau, Claudio Juan. Universidad Nacional de Rio Negro. Sede Alto Valle; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentina Fil: Molina, Wagner F.. Universidade Federal do Rio Grande do Norte; Brasil Fil: Ledesma, Mario A.. Parque Ecológico ‘El Puma’. Centro de Rehabilitación y Cría de Animales Silvestres; Argentina Fil: Martinez, Pablo A.. Universidade Federal do Rio Grande do Norte; Brasil