A dynamic global equilibrium in carnivoran diversification over 20 million years

Abstract

The ecological and evolutionary processes leading to present-day biological diversity can be inferred by reconstructing the phylogeny of living organisms, and then modelling potential processes that could have produced this genealogy. A more direct approach is to estimate past processes from the fossil record. The Carnivora (Mammalia) has both substantial extant species richness and a rich fossil record. We compiled species-level data for over 10 000 fossil occurrences of nearly 1400 carnivoran species. Using this compilation, we estimated extinction, speciation and net diversification for carnivorans through the Neogene (22 -2 Ma), while simultaneously modelling sampling probability. Our analyses show that caniforms (dogs, bears and relatives) have higher speciation and extinction rates than feliforms (cats, hyenas and relatives), but lower rates of net diversification. We also find that despite continual species turnover, net carnivoran diversification through the Neogene is surprisingly stable, suggesting a saturated adaptive zone, despite restructuring of the physical environment. This result is strikingly different from analyses of carnivoran diversification estimated from extant species alone. Two intervals show elevated diversification rates (13 -12 Ma and 4 -3 Ma), although the precise causal factors behind the two peaks in carnivoran diversification remain open questions.

The role of clade competition in the diversification of North American canids

“…However, evidence suggests diversity equilibrium for North American mammals (26), and for carnivores at a global scale (32). Our results strongly indicate that competition among several clades of canids and other carnivores drove the changes in diversification rates and the replacement of entire clades.…”

The non-uniformity of fossil preservation

“…It is unclear whether this approach is feasible for capture-mark-recapture methods that simultaneously estimate speciation, extinction and sampling rates [97], given that it may be difficult or even impossible to extract the large amounts of data from the fossil record needed to estimate the parameters of these methods.…”

“…They showed that ghost clades are explained substantially better by using confidence intervals on the oldest members of a clade that incorporate non-constant preservation. Other possible indirect proxies include the number of stratigraphic units [97], or the number of gap-bound sedimentary packages [100,104].…”

Diversification Rates and the Evolution of Species Range Size Frequency Distribution

“…We preferred this method over more traditional approaches (2008; 2000) as it is recommended for paleontological data, especially under heterogeneous and incomplete sampling (Liow and Finarelli, 2014). In fact, under the Pradel approach the absence of a species from a time bin is interpreted as either real absence or as failed-to recognize presence.…”

“…As response variables, we used alternatively the two rates (i.e., extinction and speciation) as estimated by Pradel's models (see above) and SR as explanatory variable. As extinction and speciation rates represent probabilities (Liow and Finarelli, 2014;Finarelli and Liow, 2016), we converted them into "number of successes" or "number of failures" and included into GLMMs with a binomial distribution of errors and logit link function. In both regression models, linear and quadratic terms between SR and the response variables were calculated.…”