Phylogenetic trees

evolution produces a pattern of lineages that resembles: a) a ladder b) a tree

b) a tree

should phylogenies be read left to right? why or why not?

no. right and left are arbitrary for phylogenies

what biologists use to create and narrow down clades

characters

character

heritable traits that can be compared across organisms

shared derived trait

A trait that 2 lineages inherited from the same common ancestor

node

where lineage splits, representing the last common ancestor

branches represent

lineages

root/base

the oldest lineage that is ancestral to all organisms on the tree.

tips of the branches

represent taxa (often species)

do the tips of branches always represent species?

no, they can represent populations, groups, or genes

monophyletic group/clade

group consisting of a common ancestor and all of its descendants

paraphyletic group

group containing the most recent common ancestor, but doesn’t include all descendants

polyphyletic group

contains a group of organisms but does not include the most recent common ancestor of them