Phylogenetic diversity in the Iberian flora through the Cenozoic

Abstract

Phylogenetic diversity reflects both community assembly and evolutionary diversification processes. Communities with low phylogenetic diversity might be the outcome of environmental filters favouring the occurrence and/or the diversification of lineages from particular clades. This rationale applies for regional assemblages. Here we propose to integrate phylogenetic diversity into paleobotanical studies aimed to reconstruct temporal shifts in plant assemblages in the past. To do so we first compiled a fossil dataset of 619 vascular plant taxa occurring through the Cenozoic in the Iberian flora, then we reconstructed their phylogenetic relationships, and finally we calculated temporal changes in phylogenetic diversity. The results reveal high phylogenetic diversity in the early Cenozoic (Danian to Lutetian) followed by an abrupt decline around 40 million years ago and a time interval of lower values during the Oligocene and the Miocene. A decreasing trend of phylogenetic diversity was also detected over the Piacenzian and the Early Pleistocene. Early values of high phylogenetic diversity were not explained by null models, and we speculate on putative causes related to climate. Overall, we propose to combine paleobotanical and phylogenetic information for detecting evolutionary changes that shaped our biodiversity across relevant geological scales.