Biology: Climbing Tree of Life

Phylogenetic tree

diagram shows evolutionary histroy

Branch

species through time

Nodes

common ancestors, split into 2+ groups, represents MRCA

Eukaryotic

membrane bound nucleus, usually multicellular

Prokaryotic

no nucleus, bacteria and archaea, most unicellular

Taxanomy

naming and classifying organisms

Taxon

named group

Scientific naming

Genus species

Root

ancestral population, start of tree

Tips

taxa

Monophyletic group (clade)

ancestor and all descendants

Outgroup

taxon diverged earlier, helps root true, establishes ancestral vs derived trait

Trait

charecteristic of ancestor

Derived trait

modified form of ancestral trait

Synamorphy

shared derived trait, important for recognizing traits

Polytomy

node with 3+ branches

Sister groups

two descendants split from same node and are eachother's closest relatives

Polyphyletic

shares traits but not recent common ancestor

Paraphyletic

includes ancestor but not all descendants

Homology

similar due to common ancestory

Homoplasy

similar due to independent evolution

Types of homologies

genetic, developmental, and structural

Problem phylogenies

polyphyletic, homoplasies, paraphyletic