Evolutionary radiation in canids following continental colonizations

Colonization of a new environment may trigger a remarkable radiation process, defined as an accelerated accumulation of species in a short period of time. However, how often colonization events trigger such radiations is still an open question. We studied the worldwide dispersal of the subfamily Caninae to investigate whether the invasion of new continents resulted in a great increase in species diversification. We used a combination of phylogenetic analyses and ancestral area reconstructions to estimate ancestral ranges of 56 extant and extinct species of Caninae, as well as variation in speciation and extinction rates through time and across clades. Our findings indicate that canids experienced a remarkable radiation event when lineages were able to reach Eurasia and South America around 11 million years ago. This large number of species arising in a short period of time suggests that canids experienced ecological opportunity events within the new areas, implying that the differences in the ecological settings between continents, and size variation among Canidae and other carnivores may be responsible for the variation in clade dynamics. We suggest that the advance of grasslands and the new herbivorous fauna that came with it were the major forces responsible for the diversification of wolves in North America. On the other hand, empty niches and the absence of competitors can explain the success of canids in Africa and South America. We argue that interaction with other carnivores probably also affected the diversification dynamics of canids.