Unit 4 Evolution

A __________ is a branching diagram that shows possible evolutionary relationships among groups of organisms.

phylogenetic tree

Historical groupings, such as reptiles and fish, are no longer considered valid because they are not __________.

monophyletic

A __________ is constructed by grouping taxa into nested hierarchies using information from synapomorphies.

cladogram

Characters that some members of the clade share because of common ancestry are called __________.

synapomorphies

Similar character states in different species may arise due to descent from a common ancestor (__________) or independent evolution (________).

synapomorphy, homoplasy

Tetrapods belong to a clade called __________, which includes coelacanths and lungfishes.

lobe-fins

Some tetrapod traits, such as toes and legs, evolved while their ancestors still lived in __________.

water

The bones of the mammalian ear evolved from bones of the __________ of ancestors to mammals.

lower jaw

Traits that arise for one function but are later co-opted for a different function are known as __________.

exaptations

Feathers evolved before __________, serving early functions such as insulation and courtship display.

flight

Two species that branch off from the node of a phylogenetic tree are analogous to

siblings on family tree

What is a node?

point where linage splits

What happens when a node and all descendants come together?

Clade forms

Monophyletic

The group made up of an organism and all of it’s decendants

Polyphyletic

taxonomic group that doesn’t share an immediate common ancestor

Paraphyletic

a group of organisms that share a common ancestor, although the group does not include all the descendants of that common ancestor.

Character

heritable aspect of organisms

synapomorphies

shared derived characters that imply a common ancestor

Outgroup

organisms outside of a clade (monophyletic)

homoplasy

character state similarity NOT due to shared descent (convergent evolution)