Phylogenetic Trees Flashcards
what is a phylogenetic tree?
diagram that depicts hypothesized evolutionary relationships amongst species or other taxa (or DNA or proteins)
what is a synapomorphy?
a homologous trait inherited from the MOST RECENTcommon ancestor of a group
can be structural, behavioural, molecular etc
separates a group from other monophyletic groups
what are homoplasies? aka…
OR analogous traits
- traits same by convergent evolution, independent solution to an environmental demand
tips of branches
taxa, generally rep species
tips = youngest lineage
root
the oldest lineage on tree, ancestral to all other organisms
branches
rep a lineage, ancestor to descendant, evolution occurs all along branches
length is generally meaningless
evolution occurs along vertical lines
nodes
inferred speciation event, ancestral lineage splits into 2 or more descendant lineages
internal node rep last common ancestor of two lineages
character state/marks
show when a new character state (heritable trait) arose or was lost
character state/marks
show when a new character state (heritable trait) arose or was lost
monophyletic group, aka…
CLADES
includes a unique or common ancestor and ALL of it’s descendants
paraphyletic group
includes common ancestor but NOT ALL descendants
polyphyletic group
does NOT include the most recent common ancestor
principle of parsimony
related to character marks/gain and loss of traits
the assumption that the simplest explanation is most likely true
what to pay attention to, questions about principle of parsimony
is it asking you how many times, gained, lost, or both??
what to pay attention to, questions about principle of parsimony
is it asking you how many times, gained, lost, or both??
