Multigene phylogeny of the Mustelidae: Resolving relationships, tempo and biogeographic history of a mammalian adaptive radiation

<p>Abstract</p> <p>Background</p> <p>Adaptive radiation, the evolution of ecological and phenotypic diversity from a common ancestor, is a central concept in evolutionary biology and characterizes the evolutionary histories of many groups of organisms. One such group is the Mustelidae, the most species-rich family within the mammalian order Carnivora, encompassing 59 species classified into 22 genera. Extant mustelids display extensive ecomorphological diversity, with different lineages having evolved into an array of adaptive zones, from fossorial badgers to semi-aquatic otters. Mustelids are also widely distributed, with multiple genera found on different continents. As with other groups that have undergone adaptive radiation, resolving the phylogenetic history of mustelids presents a number of challenges because ecomorphological convergence may potentially confound morphologically based phylogenetic inferences, and because adaptive radiations often include one or more periods of rapid cladogenesis that require a large amount of data to resolve.</p> <p>Results</p> <p>We constructed a nearly complete generic-level phylogeny of the Mustelidae using a data matrix comprising 22 gene segments (~12,000 base pairs) analyzed with maximum parsimony, maximum likelihood and Bayesian inference methods. We show that mustelids are consistently resolved with high nodal support into four major clades and three monotypic lineages. Using Bayesian dating techniques, we provide evidence that mustelids underwent two bursts of diversification that coincide with major paleoenvironmental and biotic changes that occurred during the Neogene and correspond with similar bursts of cladogenesis in other vertebrate groups. Biogeographical analyses indicate that most of the extant diversity of mustelids originated in Eurasia and mustelids have colonized Africa, North America and South America on multiple occasions.</p> <p>Conclusion</p> <p>Combined with information from the fossil record, our phylogenetic and dating analyses suggest that mustelid diversification may have been spurred by a combination of faunal turnover events and diversification at lower trophic levels, ultimately caused by climatically driven environmental changes. Our biogeographic analyses show Eurasia as the center of origin of mustelid diversity and that mustelids in Africa, North America and South America have been assembled over time largely via dispersal, which has important implications for understanding the ecology of mustelid communities.</p

Distribución y correlaciones de la diversidad filogenética de los carnívoros a lo largo de las Américas

Digital maps and a dated supertree of global carnivore species were used to assess the distribution of American carnivores’ phylogenetic diversity (PD, measured in millions of years) both from a geopolitical perspective (‘evolutionary heritage’ or EH) and on the basis of species’ range size and conservation status. A new measure, range-weighted EH, is introduced. This measure partitions the total PD of the tree between countries based on the proportion of species’ ranges within each country. Sociopolitical correlates of these measures were explored. Only 3%of the total PD in the Americas is endemic to any one country. As expected, the measures of PD are positively correlated with each other and with species richness. The USA contains the most species, the most EH and the second most range-weighted EH after Brazil. Indeed, larger and richer countries, and those with the lowest state-corruption-rate hold most EH. No significant differences were observed in the amount of PD remaining if species are removed at random, or following more plausible sequences based on IUCN conservation status and range size. Eighty percent of the American carnivores’ PD would remain safe if only the set of not threatened species were to remain. Roughly the same is true if only the 50% most widespread species were to persist. Samples of wide-ranging species represent more of the entire tree than do samples of narrow-ranging species, highlighting the importance of the former for conservation strategies.We suggest that similar approaches be applied to more groups across the globe to assess which countries and areas steward the most PD, as well as which species and taxa do, in order to plan conservation actions consequently

The dilemma of female mate selection in the brown bear, a species with sexually selected infanticide

Because of differential investment in gametes between sexes, females tend to be the more selective sex. Based on this concept, we investigate mate selection in a large carnivore: the brown bear (Ursus arctos). We hypothesize that, in this species with sexually selected infanticide (SSI), females may be faced with a dilemma: either select a high-quality partner based on phenotypic criteria, as suggested by theories of mate choice, or rather mate with future potentially infanticidal males as a counter-strategy to SSI. We evaluated which male characteristics were important in paternity assignment. Among males available in the vicinity of the females, the largest, most heterozygous and less inbred and also the geographically closest males were more often the fathers of the female's next litter. We suggest that female brown bears may select the closest males as a counter-strategy to infanticide and exercise a post-copulatory cryptic choice, based on physical attributes, such as a large body size, reflecting male genetic quality. However, male–male competition either in the form of fighting before copulation or during the post-copulatory phase, in the form of sperm competition, cannot entirely be ruled out