Adaptive Radiations Flashcards
Adaptive Radiations
Evolution occurs on a continuum from gradual to rapid, cause fossil record to mostly show long periods of little change interrupted by explosions of new species
Niches
Way organism uses its environment
Heterochrony
Adaptive radiations are facilitated by polyploidy or rate of development
Example of Heterochrony
Human and chimp brain sizes are different because skull growth is turned off at different times
How many mass extinctions are there in fossil record?
Five
Two most famous mass extinctions
Permian and Cretaceous
Permian ME
250 mya, 90+% of species on land and sea lost, occurred during time of Pangea
How long did it take life to recover after Permian?
5+ million years because of extreme temperatures, no life existed except for on the poles
How hot was land after Permian?
120-140 degrees F
How hot was water after Permian?
105 degrees F
Cretaceous ME
65 mya about 3/4 of all species were lost (including the dinosaurs) because of chixilub
Following Cretaceous ME
Mammals underwent a major adaptive radiation