Phylogenetic trees

Homology

similarity in characters as a result of sharing an ancestor

Homologous structures

Structures in different species that are similar due to a common ancestor

• Features that often have different functions but are structurally similar due to a common ancestor

• Ex: same skeletal elements make up the forelimbs of humans, cats, whales, and bats but they each function differently

Phylogenetics

Study of evolutionary relationships between organisms

• Study on how organisms are related

Phylogenetic trees

Visual representation of evolutionary relationships between groups of organisms

• Show evolutionary relationships not the degree of similarity

Taxa

Defined groups of organisms

Branches

lineages (group of organisms) evolving over time

• Shared evolutionary history

Internal nodes

common ancestors, point on the tree where the last common ancestor was shared before it split

Root

Lineage from where all tasa on the tree evolved

Outgroup

Distantly related taxon

• Chosen by the researcher, known to be the less related to the taza being studied

• Can help predict patterns of trait evolution

Clade

All taxa that are descendants of a shared common ancestor

Analogous traits

Evolved independently, no shared ancestor

Convergenet evolution

Independent evolution of similar traits

• Trait popping up in one lineage, same trait popping up in a different lineage

• often due to shared requirements and/or environmental conditions

Character

Heritable characteristic of an organism

Character state (trait)

Particular version of character, type of character being talked about

Morphological character

Physical features

Molecular character

DNA sequence

• Useful for very distantly (share few characters) and closely related groups

Developmental character

Shared developmental processes can reveal relatedness of species with very different morphological triats

Behavior character

Any behavior of an organism that is significantly influenced by one or more genes

Maximum parsimony

Assumes that the hypotheses with the fewer evolutionary changes are more likely

• Idea that the simplest evolution pattern is most likely

Polytomy

Branch point with three or more species coming out of it

• Don’t have enough information to determine the branching order

Derived traits

Traits that arise during the evolution of a group and differ from the traits of the ancestor