| Citation | Ziheng Yang developed statistical methods for use in construction of phylogenetic relationships and in the study of evolutionary processes at the molecular level. For the first time, he used a model-based, hypothesis-testing approach within a maximum likelihood framework. His models included the realistic possibility of unequal evolutionary rates at different molecular sites, which had a substantial impact on tree reconstruction and estimates of divergence times. He extended these models to cases where the assumption of rate constancy over time is violated. He has also used ancestral sequence reconstruction and codon-based methods to detect adaptive evolution in genes. |