USING BIOGEOGRAPHY AND PHYLOGENY TO INFER CHANGE IN BARRIERS TO DISPERSAL THROUGH TIME: A CASE STUDY OF MESOZOIC DINOSAURS (Invited Presentation)

Dispersal plays a key role in the survival and diversification of clades, community assembly, and the outcome of species interactions. An organism’s ability to disperse may be restricted by barriers such as oceans, or enhanced by innovations such as powered flight. Most paleobiogeographical methods that are currently used to model the dispersal history of clades require a priori designation of discrete areas. Here we instead combine continuous paleocoordinate data with phylogenetic data to infer the development or breakdown of barriers to dispersal through time. Mesozoic dinosaurs present an ideal case study for this framework; the history of the clade spans the break-up of Pangea and the origin of a probable dispersal enhancing trait – powered flight. Using occurrence data from the Paleobiology Database and a 1000-taxon supertree we test a set of predictions relating to key events in dinosaur evolutionary history. Initial results based on a simple correlation approach are consistent with the break-up of Pangea acting to decrease dispersal, and with powered flight acting to overcome all barriers to dispersal. Additionally we present a simulation framework that can be used to generate expected distributions of phylogenetic distance under different dispersal scenarios, implemented in R (github.com/laurasoul/dispeRse). This is based on treating dispersal of a speciating clade as bounded Brownian motion on a sphere, while new barriers are created (continental break-up) or removed (continental collision). Extension of this framework will allow investigation and modelling of the acquisition of dispersal enhancing traits such as flight or aquatic locomotion, as well as of geographic scenarios such as sea level change and the presence of land bridges.