Read each example and decide what the resulting effect on the gene pool of that population would be.

1. a zebra migrates to join a different herd of zebras.
2. competition for sunlight leads to taller trees.
3. the dna of a snake changes to make its venom stronger.
4. a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

then it only gives 4 options for 4 questions.

option 1. create new alleles from dna
option 2. brings new alleles from new populations
option 3. randomly selects alleles
option 4. favors certain alleles