Meeting Abstract

P1.153  Saturday, Jan. 4 15:30  Utilizing likelihood models for phylogenetic reconstruction from discrete phenotypic characters WRIGHT, AM*; HILLIS, DM; University of Texas at Austin wright.aprilm@gmail.com

Rate heterogeneity among characters presents challenges for the estimation of phylogenetic trees. This statement has been validated in many molecular studies to date, and we present results here exploring the issue of rate heterogeneity in morphological data sets. The issue of estimating topology when rate heterogeneity is present is exacerbated by missing data. In paleontological data sets, artifacts of preservation often lead to highly-structured missing data. Structured missing data can lead to biases in the information content of a data matrix when rate heterogeneity is present. For example, systemic lack of preservation of labile characters in a clade of interest can lead to misestimation of the rate parameters in phylogenetic estimation, leading to error in the tree. In this talk, we will explore the effects of structured missing data in morphological data sets. Using simulated data with varying degrees of rate heterogeneity, we will examine how model parameters and topologies estimated from data sets are affected by structured missing data. We will present results displaying the effectiveness of likelihood and parsimony methods for topology estimation under a range of simulation conditions and propose suggestions for mitigating the effects of structured missing data in topology estimation.