Living Environment Translated Arabic 2014 | Page 98

15.Five factors that can lead to evolution:
a. Genetic drift- gene pool can change due to chance alone.
b. Gene Flow- (migration)- organisms move into and out of
an area. This changes the alleles that are in the
populations.
c. Mutation- new alleles form through mutation. Mutations
create the genetic variation necessary for evolution.
d. Sexual selection- certain traits improve mating success.
Alleles for these traits increase in frequency.
e. Natural Selection- certain traits may be an advantage for
survival. Alleles for these traits increase in frequency.
16.Evolution is a continuous process. Environments are constantly
changing and evolution is a response to these changes.