Chapter 18 13-03-03 1:59 PM
Systematics: the branch of biology that studies the diversity of life and its
Phylogeny: the evolutionary history of a group of organisms.
Phylogenetic tree: a branching diagram depicting the evolutionary
relationships of groups of organisms.
Taxonomic hierarchy: a system of classification based on arranging
organisms into ever more inclusive categories. (traditional)
Homologous structures: characteristics that are similar in two species
because they are inherited the genetic basis of the trait from their common
Analogous (homoplasious) structures: structures that have the same
function; phenotypic similarities that evolved separately in different lineages.
Ancestral traits: a trait that was present in a distant common ancestor.
Derived traits: a new version of a trait found in the most recent common
ancestor of a group
Assume the out group is a far back common ancestor… if the trait is the
same as the outgroup, then the trait in ancestral… if