Which observation would be evidence for allopatric speciation among finch species of the galápagos islands?
a. the birds are closely related to birds found on the mainland.
b. pairs of sister species can be found on adjacent islands.
c. specific beak sizes are adaptations to the seeds of different species.
d. no pairs of sister species formed on the same island.
e. many different species have been found on the islands.

The correct answer is c. Specific beak sizes are adaptations to the seeds of different species.

Explanation:

Allopatric speciation occurs when a population of a species is isolated geographically from their group. Then these isolated populations evolve in different species due to the selective pressure of natural selection.

The best example of allopatric speciation is seen in finches that live in the Galapagos Islands. These finches are isolated due to oceans on different islands of Galapagos and they developed different types of beaks according to the food they get on their island.

Some developed large blunt beaks to crack nuts, some developed long beaks to eat flowers and due to geographical isolation they did not interbreed and developed into a new species of finch. Therefore the correct answer is c.