Tandemly repeated satellite DNA ofDolichopoda schiavazzii: A test for models on the evolution of highly repetitive DNA

The evolutionary relationships among the Carnivora were studied in a phylogenetic analysis based on the complete mitochondrial cytochromeb gene. The study, which addressed primarily the relationships among the Caniformia, included 4 feliform and 26 caniform species, with 9 pinnipeds. The analysis identified five caniform clades: Canidae, Ailuridae (with the monotypic lesser panda), Musteloidea (Mustelidae+Procyonidae), Ursidae (including the giant panda), and Pinnipedia. The closest relatives of the Pinnipedia among terrestrial caniforms were not identified conclusively. Our analysis shows that the skunks are only distantly related to remaining mustelids (Mustelidae sensu stricto) and that the family Mustelidae, including the skunks, is paraphyletic. The relationship among the five caniform clades was unresolved, suggesting an evolutionary separation within a relatively short period of time. Based on distance values, we propose that this primary diversification took place 45 million years ago.     

Sexual size dimorphism in musteloids: An anomalous allometric pattern is explained by feeding ecology

Rensch's rule states that sexual size dimorphism (SSD) increases with body size in taxa where males are larger, and decreases when females are larger. The dominant explanation for the trend is currently that competitive advantage for males is greater in larger individuals, whereas female size is constrained by the energetics of rearing offspring. This rule holds for a variety of vertebrate taxa, and opposing trends are rare. We examine the allometry of SSD within the Musteloidea and demonstrate a hypo‐allometry contrary to Rensch's rule, with lower SSD associated with larger body size. We provide evidence that feeding ecology is involved. Where diet promotes group‐living, the optimal strategy for the males of larger species is often not to attempt to defend access to multiple females, obviating any competitive advantage of relatively greater size. We conclude that the effect of feeding ecology on mating systems may be a hitherto neglected factor explaining variation in SSD.     

Shared extremes by ectotherms and endotherms: Body elongation in mustelids is associated with small size and reduced limbs

An elongate body with reduced or absent limbs has evolved independently in many ectothermic vertebrate lineages. While much effort has been spent examining the morphological pathways to elongation in these clades, quantitative investigations into the evolution of elongation in endothermic clades are lacking. We quantified body shape in 61 musteloid mammals (red panda, skunks, raccoons, and weasels) using the head‐body elongation ratio. We also examined the morphological changes that may underlie the evolution toward more extreme body plans. We found that a mustelid clade comprised of the subfamilies Helictidinae, Guloninae, Ictonychinae, Mustelinae, and Lutrinae exhibited an evolutionary transition toward more elongate bodies. Furthermore, we discovered that elongation of the body is associated with the evolution of other key traits such as a reduction in body size and a reduction in forelimb length but not hindlimb length. This relationship between body elongation and forelimb length has not previously been quantitatively established for mammals but is consistent with trends exhibited by ectothermic vertebrates and suggests a common pattern of trait covariance associated with body shape evolution. This study provides the framework for documenting body shapes across a wider range of mammalian clades to better understand the morphological changes influencing shape disparity across all vertebrates.     

Phylogenetic relationships within caniform carnivores based on analyses of the mitochondrial 12S rRNA gene

The complete 12S rRNA gene of 32 carnivore species, including four feliforms and 28 caniforms, was sequenced. The sequences were aligned on the basis of their secondary structures and used in phylogenetic analyses that addressed several evolutionary relationships within the Caniformia. The analyses showed an unresolved polytomy of the basic caniform clades; pinnipeds, mustelids, procyonids, skunks,Ailurus (lesser panda), ursids, and canids. The polytomy indicates a major diversification of caniforms during a relatively short period of time. The lesser panda was distinct from other caniforms, suggesting its inclusion in a monotypic family, Ailuridae. The giant panda and the bears were joined on the same branch. The skunks are traditionally included in the family Mustelidae. The present analysis, however, showed a less close molecular relationship between the skunks and the remaining Mustelidae (sensu stricto) than between Mustelidae (sensu stricto) and Procyonidae, making Mustelidae (sensu lato) paraphyletic. The results suggest that the skunks should be included in a separate family, Mephitidae. Within the Pinnipedia, the grouping of walrus, sea lions, and fur seals was strongly supported. Analyses of a combined set of 12S rRNA and cytochromeb data were generally consistent with the findings based on each gene.     

Mitogenomic analyses of caniform relationships

Extant members of the order Carnivora split into two basal groups, Caniformia (dog-like carnivorans) and Feliformia (cat-like carnivorans). In this study we address phylogenetic relationships within Caniformia applying various methodological approaches to analyses of complete mitochondrial genomes. Pinnipeds are currently well represented with respect to mitogenomic data and here we add seven mt genomes to the non-pinniped caniform collection. The analyses identified a basal caniform divergence between Cynoidea and Arctoidea. Arctoidea split into three primary groups, Ursidae (including the giant panda), Pinnipedia, and a branch, Musteloidea, which encompassed Ailuridae (red panda), Mephitidae (skunks), Procyonidae (raccoons) and Mustelidae (mustelids). The analyses favored a basal arctoid split between Ursidae and a branch containing Pinnipedia and Musteloidea. Within the Musteloidea there was a preference for a basal divergence between Ailuridae and remaining families. Among the latter, the analyses identified a sister group relationship between Mephitidae and a branch that contained Procyonidae and Mustelidae. The mitogenomic distance between the wolf and the dog was shown to be at the same level as that of basal human divergences. The wolf and the dog are commonly considered as separate species in the popular literature. The mitogenomic result is inconsistent with that understanding at the same time as it provides insight into the time of the domestication of the dog relative to basal human mitogenomic divergences.