Rapid action in the Palaeogene, the relationship between phenotypic and taxonomic diversification in Coenozoic mammals

Abstract

A classic question in evolutionary biology concerns the tempo and mode of lineage evolution. Considered variously in relation to resource utilization, intrinsic constraints or hierarchic level, the question of how evolutionary change occurs in general has continued to draw the attention of the field for over a century and a half. Here we use the largest species-level phylogeny of Coenozoic fossil mammals (1031 species) ever assembled and their body size estimates, to show that body size and taxonomic diversification rates declined from the origin of placentals towards the present, and very probably correlate to each other. These findings suggest that morphological and taxic diversifications of mammals occurred hierarchically, with major shifts in body size coinciding with the birth of large clades, followed by taxonomic diversification within these newly formed clades. As the clades expanded, rates of taxonomic diversification proceeded independently of phenotypic evolution. Such a dynamic is consistent with the idea, central to the Modern Synthesis, that mammals radiated adaptively, with the filling of adaptive zones following the radiation.

Phylogenetic fields through time: temporal dynamics of geographical co-occurrence and phylogenetic structure within species ranges

“…The phylogeny was built upon the tree provided by Raia et al [8], whose topology and (calibrated) ages of higher level clades were in turn derived from a species-level mammal supertree [33]. This supertree combines different phylogenetic hypotheses (molecular and morphological) into a single tree, calibrated with both molecular and fossil dates (see [33] for details).…”

“…This supertree combines different phylogenetic hypotheses (molecular and morphological) into a single tree, calibrated with both molecular and fossil dates (see [33] for details). Ages of inner nodes not taken from Bininda-Emonds et al [33] were retrieved directly from the fossil record [8]. Individual sub-phylogenies of fossil mammals were subsequently added according to specialists' opinions (see [8] for details).…”

“…molecular phylogenies or fossil occurrences data) biases our understanding of evolutionary influences on biodiversity. Thus, recent claims favour a formal integration of the neontological and palaeontological perspectives to fully understand the patterns and processes in biodiversity over time and space [7][8][9][10][11]. In fact, several studies of current biodiversity now routinely include fossils, or apply phylogenetic comparative methods directly to fossil data (see [11] and references therein).…”

Patterns of maximum body size evolution in Cenozoic land mammals: eco-evolutionary processes and abiotic forcing

“…The ecological opportunity provided by the end Cretaceous extinction, which eliminated dinosaurs and other large-bodied taxa, led to a rapid increase in mammal body size [1][2][3][4]. Within 30 Myr, mammals ranged in size from 2 g to over 10 tons, filling a variety of ecological niches [2].…”

“…We reached the same conclusion by analysing the MxSF pattern. Moreover, Raia et al [4] show that both taxonomic and phenotypic (i.e. body size) evolution were drastic and highly correlated in the Palaeogene but not in the Neogene.…”