Chapter 4 Flashcards
What is Tiktaalik?
transitional fossil between fish and tetrapods
Define Phylogeny:
A visual representation of the evolutionary history of populations, genes, or species.
Define tips:
terminal ends of an evolutionary tree, representing species, molecules, or populations being compared.
Branches
Lineages evolving through time between successive speciation events.
Nodes
a point in a phylogeny where a lineage splits( a speciation event)
Internal Nodes
Nodes within a phylogeny representing ancestral populations or species.
Clade
An organism and all of its descendants.
Monophyletic
a group made of up of an organism and all its descendants.
Characters
Heritable aspects of organisms that can be compared across taxa.
Taxon (taxa)
A group of organisms that a taxonomist judges to be a taxonomic unit, such as a species or order.
Synapomorphy
A shared derived character.
Shared derived character
one that evolved in the immediate common ancestor of a clade and was inherited by all its descendants.
Cladistics
Phylogenetic methods that construct trees by grouping taxa into nested hierarchies (clades) according to their shared derived characters(synapomorphies).
Homoplasy
Character state similarity not due to shared descent. Produced by convergent evolution or evolutionary reversal.
Convergent Evolution
The independent origin of similar traits in separate evolutionary lineages.
Evolutionary Reversal
the reversion of a derived character state to its ancestral state.
Exaptation
A trait that originates performing one function, and which is later co-opted for a new function.
Australopithecine
any of a genus (Australopithecus) of extinct southern and eastern African hominids that include gracile and robust forms with near-human dentition and a relatively small brain