Phylogeny and Classification: Organismal

Phylogeny

The evolutionary history of a species or group of related species

Discipline of systematics

Classifies organisms and determines their evolutionary relationshipsthrough the study of their characteristics and genetics.

Taxonomy

The ordered division and naming of organisms

Sister Taxa

Groups that share an immediate common ancestor

Phylogenetic tree

shows patterns of descent, provides important information about similar characteristics, and serves a value in understanding evolutionary relationships.

Homology

Similarity due to SHARED ANCESTOR. Similar in fundamental stuctures.

Analogy

Similarity due to CONVERGENT EVOLUTION (NO COMMON ANCESTOR). Differ in fundamental structure

More complex features

More likely homologous

Clade

Group of species that includes an ancestral species and all its descendants

Monophyletic

Ancestral species and ALL its descendants

Paraphyletic

Ancestral species and SOME of its descendants

Polyphyletic

Members have different ancestors (AVOID)

Example of Monophyletic

Dogs (the wolf), Birds (Reptilian), Lemurs, Snakes

Example of paraphyletic

Reptiles (DONT include birds), Fish (human had 4 limbs)

Example of polyphyletic

insectivores

Maximum Parsimony

The tree that requires the fewest evolutionary events (US APPEARANCES OF SHARED DERIVED CHARACTERS)

Maximum likelihood

Given “rules” about how DNA changes over time, most likely demonstrates sequence of evolutionary events. (Uses statistics)

Phylogenetic Analysis

HIV descended from viruses that infect chimps, other primates.