A scientist focusing on the evolutionary history of specific significant traits is engaged in

A scientist focusing on the evolutionary history of specific significant traits is engaged in cladistics.

Cladistics is a method of biological classification in which organisms (plants and animals) are grouped based upon shared significant derived characteristics (synapomorphies). Cladistics identifies various significant shared traits that can be traced to the most recent common ancestor of a group of species and that are not found in more distant groups and ancestors. Cladistics uses various anatomical, molecular and genetic characteristics of organisms.