speciation & extinction. Flashcards
define speciation.
over long periods of time, natural selection can give rise to the formation of new species.
define extinction.
a species dies out. no individuals left of that species.
what condition are needed for speciation?
population needs to be geographically isolated from one another.
prevented from breeding from another. (reproductive isolation.)
what is the process of speciation?
isolation- can’t reproduce with other group. population becomes isolated from original population.
genetic variation- genetical differences within a species.
natural selection- those with characteristics best suited to their environment survive and reproduce which passes on those genes to offspring and then those genes become more common in population.
speciation- isolated population changes and is no longer able to interbreed with old population.
why might organisms become extinct?
diseases.
new predators.
lack of resources/ prey dies out.
changes to the environment- climate change, habitat loss.
catastrophe- volcano eruption, meteor, changes to the environment geological time.
hunted to extinction.
how did Alfred Russel Wallace’s discovery link to Darwin’s theory of natural selection?
his work on butterfly’s provided evidence for natural selection.
what did wallace discover about colouration in animals?
used by some species to deter predators from eating them.
define species.
group of organisms that can breed to produce fertile offspring.
