bio phylogeny (main idea 2)

what is used to construct phylogenetic trees or cladograms?

shared characters

what can be used to infer a phylogeny?

homologous characters (once they have been idenfided)

what do cladograms classify organisms by?

common descent

what is a shared derived character?

an evolutionary novelty unique to a particular clade

what is the outgroup?

the organisms that has diverged before the ingroup

— the outgroup does not have any shared characteristics with the group

each ingroup species is compared with the outgroup to..

differentiate between shared derived characteristics

in some trees, what can the length of a branch reflect?

the number of genetic changes that have taken place in a particular DNA sequence in that lineage

in other trees what can branch length represent?

chronological time and branching points can be determined by fossil record