Evolution of discrete and continuous morphological characters

Advances in the acquisition and analysis of genetic sequence data have led to an increasing emphasis and reliance on molecular data to build phylogenies and test models of evolution, yet phenotypic evidence (morphology) remains vital. Morphology is the only way to incorporate fossil data, and provides a direct link between organisms and their environment (Lee 2015). Morphological characters, however, are fundamentally different from molecular characters and lack any defined common model of evolution. This project aims to test models of character evolution using empirical and simulated morphological data and the use of these models in phylogenetics. To achieve this, empirical datasets of modern groups comprising molecular and morphological phylogenetic data will be compiled (Sansom et al 2017, Sansom and Wills 2017). Continuous and discrete morphological characters will be applied to molecular trees to test for different models of evolution (i.e. drift, directional selection etc), and the prevalence of character correlation will be assessed. Different approaches to character analysis will be applied and compared in terms of phylogenetic performance and inferred modes of evolution i.e. elimination of correlated characters, continuous characters versus discretized characters (Randle and Sansom 2016). Results from empirical analyses will be compared with simulation data generated using our bespoke software (TReEvoSim, Keating et al in review; REvoSim, Garwood et al in review) under differing parameters ranging from complete drift to strong natural selection. These combined approaches will enable characterization of modes of morphological evolution, enable probabilistic model-based phylogenetic analyses of morphological data to keep pace with those of molecular data, and ultimately bring morphology from the 19th century into the 21st.