study of biological diversity and evolutionary relationships among organisms, both extant and extinct
similarities among various species that occur bc the species are derived from a common ancestor. (ex. arm of human , bat wing, flipper whale)
involves analysis of genetic data to identify and study genetic homologies and propose phylogenetic trees
for example, among diff species, a front limb, which is a character, may exist in different character states such as a wing, an arm, or a flipper.
a character that is shared by two or more different taxa and inherited from ancestors older than their last common ancestor
a character that is shared by two or more species or taxa and has originated in their most recent common ancestor
compared to shared primitive characters, shared derived characters are more recent traits on an evolutionary timescale
states that the preferred hypothesis is the one that is the simplest for all the characters and their states. (one approach for choosing among possible phylogenetic trees is to assume that the best hypothesis is the one that requires the smallest number of evolutionary changes.
what is the probability that an evolutionary model and a proposed phylogenetic tree would give rise to the observed data?
what is the probability that a particular phylogenetic tree is correct given the observed data and a particular evolutionary model