Phylogeny and the Tree of Life AP Biology Crosby High School

Taxonomy Binomial Nomenclature Hierarchical Classification PhyloCode? Genus specium Hierarchical Classification Domain Kingdom Phylum Class Order Family Genus Species PhyloCode?

Terminology Dichotomies Sister Taxa Rooted Basal Taxon Polytomy

Cladistic Analysis Clade Cladogram: Phylogenetic diagram Dichotomies Monophyletic (“single tribe”)

Constructing a Cladogram Created from Homology not Analogy More similar Homologies are more closely related The more complex two structures are the more likely they are homologous Shared Primitive Character: common to more inclusive taxon Mammal backbone Shared Derived Character: unique to defined taxon Mammal hair

Outgroup Comparison Outgroup: Very distant from studied Organisms Ingroup: Studied Organisms Which one of these things is not like the other? Ancestor more recent, not species

Molecular Cladograms Constructed from differences in DNA sequences rRNA used for taxa that diverged from 100s to millions of years ago mtDNA used for more recent divergences Insertions and Deletions must be accounted for

Parsimony Keep it simple Requires the least amount of changes or evolutions to occur

Phylogenetic Trees are Hypotheses They are a guess Most parsimonious = most accepted Unless evidence proves otherwise The same evolutionary event occuring more than once in unrelated cases is unlikely Strongest hypotheses are supported by morph., molec., and fossil record

Parsimony

DNA Allignment

Outgroup Comparison