AP Bio Chapter 26

Phylogeny

the evolutionary history of a species or group of related species

systematics

classifies organisms and determines their evolutionary relationships

Taxonomy

the ordered division and naming of organisms

Phylogenic Tree

represents a hypothesis about evolutionary relationships among groups

A binomial

a two-part Latinized name consisting of the name of the genus and the specific epithet

domain kingdom phylum class order family genus species

order of divisions from broad to specific

Taxon

a taxonomic unit at any level

Dichotomy

a two-way branch point in a phylogenic tree

sister taxa

share an immediate common ancestor, each other’s closest relatives

Basal taxon

one that diverged early in the evolutionary history of a group

homology

similarities due to shared ancestry

analogy

similarity due to convergent evolution

convergent evolution

unrelated species develop similar features because natural selection has led to similar adaptations

cladistics

bases clarification on common ancestry and nests clade within clades

clade

a monophyletic group that consists of an ancestral species and all of its descendant species

paraphyletic group

excludes some species in the group

polyphyletic group

includes several distantly related species but not their most recent common ancestor

shared ancestral characters

found in a particular clade but originated in an ancestor that is not part of that clade

shared derived characters

unique to a particular clade

outgroup

a species or group the diverged before the group being studied (ingroup)

ingroup

the species being studied

maximum parsimony

assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely

maximum likelihood

given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events

phylegenetic bracketing

allows us to predict features of an ancestor from features of its descendants

orthologous genes

are found in a single copy in the genome and are homologous between species

They can diverge only after speciation occurs

paralogous genes

result from gene duplication, so are found in more than one copy in the genome

They can diverge within the clade that carries them and often evolve new functions

molecular clocks

uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change

horizontal gene transfer

is the movement of genes from one genome to another

occurs by exchange of transposable elements and plasmids, viral infection, and fusion of organisms

complicates efforts to build a tree of life

archaea bacteria eukarya

three- domain system