What happened to the greenish warbler birds as they migrated from the southern portion of their range up around the Tibetan Plateau? a. They evolved separately as they moved north and became two separate species. b. The original species died off, but the ones that were able to adapt to a northern climate evolved into a new species. c. As a whole the species was able to adapt to a colder climate, but no significant changes occurred. d. They were unable to adapt and evolve to ensure their survival and became extinct. Please select the best answer from the choices provided A B C D

The correct answer is - option A. They evolved separately as they moved north and became two separate species

Explanation:

Greenish warbler is a leaf warbler present in many regions in the world and shows migration in winters in the Indian region. The main region of the migration is Tibetan Plateau.

They migrated from the southern part of these birds range and moved north and evolved separately from the main species and become two distinct species due to their geolocation and environment change.

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:

i think it is dna, i'm not totally sure but i think it might be.