The evolutionary history of a group of species is called it phylogeny and a phylogenetic tree is a. Estimating evolutionary trees graphical summary of this history. An evolutionary tree describes the patter, and in some cases the timing, of events that occurred as species diversified. It also records the sequence in which lineages appeared and documents which organisms are more closely or distantly related. The most closely related taxa should have the most traits in common. Many types of characters could qualify: the sequence of nucleotides in a particular gene, the presence or absence of specific skeletal elements or flower parts, or the mode of embryonic or larval development. They are shared, derived traits: any group that includes an ancestor and all of its descendants is called a monophyletic group (or clade or lineage) This means all synapomorphies are homologous traits but not all homologous traits are synapomorphies.