Meeting Abstract
Sample size and phylogenetic signal are important and related factors in phylogenetic comparative evolutionary analyses; however, methods for assessing minimum taxonomic resolution are currently lacking. Previously, we have measured hardness and elastic modulus values in enamel and orthodentine from a broad sample of Gnathostomata. The distribution of these values demonstrated a lack of phylogenetic signal, potentially due to small sample size given the longevity of the clade. Here we tested whether low phylogenetic signal is robust to increased sampling using paired (non-randomized and randomized) simulation studies. In the first simulation, genus-rank sister taxa of represented species were added to the phylogenetic tree and assigned simulated material properties derived from the previously measured values of their congeners. In the second simulation, added taxa were instead assigned material properties randomly from a distribution of the entire materials dataset with bootstrap resampling. Both simulations were performed for 200 iterations, from which phylogenetic signal was estimated. Analysis of the simulations identified an increase in phylogenetic signal for both hardness and elastic modulus of dental tissues at higher levels of taxonomic representation, suggesting that additional sampling is necessary to elucidate underlying evolutionary processes. Further analyses should consider the needs of robust sampling to ensure that the relationships between evolutionary relatedness, dental materials, and diets can be meaningfully addressed.
