what does continental drift promote
allopatric speciaiton
rgions that were one closeby,are now saparated by a barrier
what is adaptive radiation
periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles, or niches, in their communities.
when did large scale adaptive radiations occur?
after each of the big five mass extinctions, when survivors became adapted to the many vacant ecological niches
wen does adaptive radiation occur in geographically limited areas
when a few organisms make their way to a new, often distant location in which they face relatively little competition from other organisms
according to fossil records, the ___ of species that ever lived are now ___
majority
extinct
why would a species become extinct?
- habitat is destroyed
- environmental changes
Permian mass extinction, which defines the boundary between the ___ and ___ eras
Permian mass extinction, which defines the boundary between the Paleozoic and Mesozoic eras
which mass extinction?
claimed about 96% of marine animal species and drastically altered life in the ocean
The Permian mass extinction
which mass extinct?
occurred during the most extreme episode of volcanism
the Permian mass extinction
which mass extinction?
extincted dinosaurs?
Cretaceous
clue for the Cretaceous extinction
thin layer of clay enriched in iridium that separates sediments from the Mesozoic and Cenozoic eras
clue for the Permian extinction
ash was detected in Permian-aged rocks in the Canadian arctic.
where would Iridium come from
meteorites and other extraterrestrial objects
after the Permian and Cretaceous mass extinctions, the percentage of ___ organisms that were ___ increased substantially
after the Permian and Cretaceous mass extinctions, the percentage of marine organisms that were predators increased substantially
what does a rise in the number of predator species increase ?
the risks faced by prey and
the competition among predators for food.
what are the two parts of binomial nomenclature
genus + epithet
what is a genus
to which specie it belongs
what is epithet
unique for each species within the genus
where is extinction more likely
in small populations sizes
most species that have ever lived are ___
extinct
what have fossil records helped establish
geologic records
which came before? permian/cructacean
?
eras are defined by:
mass extinctions
followed by adaptive radiation (new habitats available, new species)
what is the extinction rate on earth
steady background extinction with periodic mass extinctions (5)
