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Data and code from: Evaluating phylogenetic comparative methods under reticulate evolutionary scenarios

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Sep 11, 2026 version files 1.14 GB

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Abstract

Phylogenetic comparative methods (PCMs) are widely used to study trait evolution. While a treelike history is typically assumed, many evolutionary histories involve reticulation, such as hybridization, that violates core assumptions of these methods. In this study, we evaluate how such violations affect inferences of ancestral character states, evolutionary rates, and model selection using commonly used PCMs. Using random forest, generalized linear models, and model-based clustering, we identify the key factors contributing to these inaccuracies. 

In order to do this, we first simulated thousands of phylogenetic networks with various patterns of gene flow, inheritance probabilities, and numbers of reticulation events. Then, we simulated continuous traits evolving under brownian motion, with various rates of trait evolution and transgressive segregation events. To evaluate the adequacy of traditional tree-based PCMs, we then extracted the major tree for each network, along with tip states for our simulated traits, and performed ancestral character estimations. We calculated tree-wide trait estimation error, node-specific error, evolutionary rate estimation error, and evolutionary model misspecification. Finally, we simulated 10,000 traits evolving under brownian motion using our major tree topologies in order to establish a baseline expectation of error distribution when traits evolve on trees and tree-based methods are used.