Ch. 26: Phylogeny and the Tree of Life

By Ben Karlsberg

Taxonomic Classification Order(More specific on top, less towards bottom)

Example classification of a bear

Binomial nomenclature First part is Genus Second part is Species Only Genus capitalized Ex. Ursus arctos

Phylogenetic tree- history of a group of organisms

Analogy and Homology Analogy- constructing a phylogeny due to

convergent evolution Homology- constructing a phylogeny due to

shared ancestry Homoplasies- Analogous structures that

arose independently

Cladistics- classifying based on common ancestry3 Clades- monophyletic, paraphyletic, polyphyletic

Claudes Monophyletic- consists of ancestral species and

all descendents Paraphyletic- ancestral species and some of

descendents Polyphyletic- includes taxa (unit of hierarchy)

with different ancestors

Types of homologous genes Orthologous genes- found in different

species because of speciation Paralogous genes- result from gene

duplication, so they are found in more than one copy in the same genome

Molecular clock A yardstick for measuring the absolute time

of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates

Neutral Theory Much of evolutionary change in genes and

proteins has no effect on fitness and therefore is not influenced by Darwinian selection

Three domains of life

The End