Testing for Treeness: Lateral Gene Transfer, Phylogenetic Inference, and Model Selection

Introduction – Smoking and Non-smoking Guns: Sometimes it may seem obvious that a lateral gene transfer (LGT) event has occurred. For example, consider the fact that a multi-gene phylogenetic analysis of Rafflesiacaea, a family of flowering plants that includes Rafflesia arnoldii, which has the largest flower in the world, places it within the order Malpighiales, a diverse order containing such plants as willow trees and poinsettias. However, analysis of its Mitochondrial gene nad1B-C places it within the grape family Vitaceae in the order Vitales, a distantly related taxon (Davis and Wurdack 2004). This discordance is easily explained when we note that Rafflesiacaea is an endophytic parasite and the nad1B-C gene analysis places it near its host Tetrastigma. The obvious conclusion to draw is that there was an LGT event transferring mtDNA from host to parasite.