Continental faunal exchange and the asymmetrical radiation of carnivores

Abstract

Lineages arriving on islands may undergo explosive evolutionary radiations owing to the wealth of ecological opportunities. Although studies on insular taxa have improved our understanding of macroevolutionary phenomena, we know little about the macroevolutionary dynamics of continental exchanges. Here we study the evolution of eight Carnivora families that have migrated across the Northern Hemisphere to investigate if continental invasions also result in explosive diversification dynamics. We used a Bayesian approach to estimate speciation and extinction rates from a substantial dataset of fossil occurrences while accounting for the incompleteness of the fossil record. Our analyses revealed a strongly asymmetrical pattern in which North American lineages invading Eurasia underwent explosive radiations, whereas lineages invading North America maintained uniform diversification dynamics. These invasions into Eurasia were characterized by high rates of speciation and extinction. The radiation of the arriving lineages in Eurasia coincide with the decline of established lineages or phases of climate change, suggesting differences in the ecological settings between the continents may be responsible for the disparity in diversification dynamics. These results reveal long-term outcomes of biological invasions and show that the importance of explosive radiations in shaping diversity extends beyond insular systems and have significant impact at continental scales.

Interactions within and between clades shaped the diversification of terrestrial carnivores

“…Considering our recent results on the diversification of Carnivora (Pires et al. ) we expected to find self‐diversity dependence to be more common in Eurasia than in North America. We also tested the hypothesis that some of the carnivoran clade replacements proposed previously (Van Valkenburgh ) were in fact driven by diversity‐dependent effects and whether these effects acted primarily through speciation or extinction dynamics.…”

“…Moreover, the analysis of individual clades reveals that certain lineages that have migrated between North America and Eurasia underwent evolutionary radiations, where diversification rates were initially high and dropped thereafter (Pires et al. ). It is therefore likely that diversity‐dependent effects played an important role in the diversification of clades within Carnivora, and such effects may have been structured very differently in each continent.…”

Biodiversity and Topographic Complexity: Modern and Geohistorical Perspectives

“…The spatial turnover of species is greater there, and many range boundaries follow major physiographic features (Figure 2B). Using process-based diversification models that incorporate specific aspects of geologic history (e.g., [44,45]), we can evaluate whether the diversification history for clades and regional faunas changed during particular intervals of tectonic or climatic history (Box 2 and Figure 3). …”

Detecting diversification rates in relation to preservation and tectonic history from simulated fossil records

“…However, an increase in faunal similarity across spatial scales in the active region from 17 to 14 Ma suggests that range shifts were contributing to species richness patterns (Badgley et al 2015). Spatially explicit modeling approaches (e.g., Pires et al 2015;Silvestro et al 2016) that can incorporate species exchange between the tectonically active and quiescent regions-for instance, due to climate warming and range shifts to higher elevations-may elucidate the biogeographic processes contributing to the strengthening and weakening of the TDG gradient over geologic time. Given highresolution temporal and spatial coverage of fossil occurrences, it is possible to track the geographic distribution of lineages throughout their history to identify immigration events and range shifts over regional scales (Jablonski et al 2006;Stigall and Lieberman 2006;Maguire and Stigall 2008;Terry et al 2011).…”