Which of the following statements is true?

geographic isolation is the main cause of speciation.
hybrid organisms always produce sterile offspring.
if a population is spread out over too large area, they may become extinct.
speciation can only happen when a population has very low genetic diversity.


a population of oak trees is separated by a large canyon. which of the following is most likely to occur?
the two populations will show cospeciation.
the genetic variation between the two populations will increase.
natural selection will cause one population to die, and the other to live.
both populations will stop evolving.


choose all the answers that apply.

extinction:
only happens above the species level
cannot happen to more than one species at a time
can be caused by habitat destruction
happens when a species or population dies out


which of the following statements is true?
gene flow evens out genetic differences between populations.
genetic drift increases the genetic differences between populations.
natural selection, mutation, and genetic drift are random events.
the bottleneck effect increases the genetic diversity of a population.


a species is endangered if it
no longer exists anywhere on earth
is in danger of becoming extinct
is not native the environment
has high genetic diversity


genetic drift
is a predictable event
increases genetic differences between populations
happens when random events change the genotype of a population
happens when well-adapted organisms survive and reproduce more often than poorly-adapted organisms