Under which of the following conditions will speciation not occur?
a. logging operations in a forest cut a single population of beetles in two so that they can no longer mix.
b. some snails in a population develop shells that twist to the right instead of the left, which makes mating impossible with partners of opposite shell shape.
c. a newly constructed housing development divides the habitat of a bird species in two, forcing the birds to fly from one section to the other
d. some females of a species of spider prefer to mate with males that have red markings while other females prefer

the reason the two sea urchins don't compete with each other for food, resources, etc. is because the urchins have adapted to the environment but they have also adapted to each other. this is most likely because the genes of the sea urchins.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation: