Question

two species of finches (a small songbird) live on an island in the pacific ocean. one species has a small, pointed beak and eats very small seeds. the other species has a large beak and can crack open larger seeds. scientists hypothesize that a small flock of finches from the nearby mainland colonized the island long ago. the finches on the mainland have medium-sized beaks and eat medium-sized seeds. which type of investigation would best allow scientists to test their hypothesis?
a. compare the dna of mainland birds and island birds.

b. try breeding the island birds with the mainland birds.

c. offer both island and mainland birds other foods besides seeds.

d. observe and record the number of seeds eaten by island and mainland birds.

Explanation:

To test if island finches colonized from the mainland, comparing DNA (genetic material) is key. DNA comparison shows genetic relatedness. Breeding (B) tests interbreeding ability, not origin. Offering other foods (C) relates to diet flexibility, not origin. Counting seeds eaten (D) relates to diet quantity, not origin. So A is best as DNA similarity supports the colonization hypothesis.

Answer:

A. Compare the DNA of mainland birds and island birds.