Biology Chapter 20

Phylogenetic Trees

diagram of the evolutionary history of species constructed through genomic sequencing

Taxon

A group of names species

Clade

a taxon that contains all the descendants of a common ancestor

Sister species

two species that are each others closest relatives

Sister clades

two clades that are each others closest relatives

Homologous traits

traits shared by two or more species that are inherited from a common ancestor

Ancestral trait

a trait that was present in the ancestor of a group

Derived trait

a trait in a descendant that differs from its ancestor

Synapomorphies:

Homologous features shared between species that are derived from a common ancestor and enable those species to carry out the same functions

Analogous Trait

different features between two species that enable them to carry out similar functions. Not derived from a common ancestor and arise FROM CONVERGENT EVOLUTION SPECIFICALLY

Convergent evolution

Independently evolved traits across different species that are similar to each other. Analogous traits

Evolutionary reversal

When a species reverts back to the ancestral state from its derived state

Homoplasies

Similar features between unrelated species that develop through convergent evolutoin, evolutionary reversal, or parallel evolution

Parsimony Principle

the simplest explanation is the preferred explanation

Morphology

study of form and structure of organisms

Behavior

Can be inherited or culturally transmitted

ex: bird calls are learned, so not useful for phylogeny

frog calls are genetic, useful for phylogeny

Molecular clock

Average rate at which a gene or protein accumulates changes

Monophyletic

Just a clade. part of the tree that includes common ancestor and all descdendants

Pholyphyletic

a group that does not include the common ancestor

Paraphyletic

includes common ancestor but not all descendants