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Macroevolution
large-scale evolutionary changes that take place over long periods of time
Microevolution
evolutionary change within a species or small group of organisms, especially over a short period.
Speciation
the formation of new and distinct species in the course of evolution.
adaptive radiation
the rapid increase in the number of species with a common ancestor
cladogram
a branching diagram showing the cladistic relationship between a number of species.
Phylogeny
Evolutionary history of a species or group of species.
fossils
describe macroevolutionary patterns
evolutionary radiation
a clade undergoes a high rate of speciation in a relatively short period of geological time
when does a non-adaptive evolutionary radiation occur
when a large population is broken into many isolated habitat types than existed previously
Why does adaptive radiation happen?
as a response to the opening of new geological niches
niche
the role an organism plays in the community
what two scenarios can cause a new niche to form
adaptive radiation occurs in response to the evolution of a new beneficial phenotype
when the environment changes and creates new niches that had not previously existed in a location
beneficial phenotype
refers to a new character that results in higher fitness in a particular environment for those organisms that possess the character -- organisms are able to outcompete other species that were already in that environment, filling all ecological niches previously occupied
hypsodonty
high crowned teeth
mammals that eat soft foods have (high/low) crowned teeth
low
what is the benefit of having high crowned teeth
slows the damage that results from a diet of high grasses
hypsodonty index
crown height / crown length
grazers
animals that feed on grasses and other monocots
browsers
animals that feed on trees and bushes
grazers have a (flat/round) muzzle
flat -- enables grazers to crop grass at ground level
browsers have a (flat/round) muzzle
round -- can pull leaves off tress and bushes
postorbital bar
the bone that closes the back of the eye socket
a complete postorbital bar indicates a (grazer/browser)
grazer -- strong temporalis muscles needed to chew repeatedly
