Question

apple maggots are a type of insect native to north america. at one time, apple maggots in north america fed only on hawthorn trees. after apple trees were introduced to north america in the 1800s, some apple maggots began feeding on apple trees while others continued to feed on hawthorn trees.

many scientists consider apple maggots to be in the beginning stages of speciation. which hypothesis best explains why apple maggots are speciating?

a. apple trees and hawthorn trees are found different environments, so apple maggots that feed on apple trees are found near those that feed on hawthorn trees.

b. apple maggots mate on any type of tree, so apple maggots that feed on apple trees frequently mate with those that feed on hawthorn trees.

c. apple maggots only mate on trees they feed from, so apple maggots that feed on apple trees are reproductively isolated from those that feed on hawthorn trees.

d. apple trees and hawthorn trees are found in similar environments, so apple maggots that feed on apple trees are geographically isolated from those that feed on hawthorn trees.

Explanation:

To determine the best hypothesis for apple maggot speciation, we analyze each option:

• Option A: If they are near each other, gene flow would occur, not speciation. Eliminate.
• Option B: Frequent mating between the two groups would prevent reproductive isolation, a key for speciation. Eliminate.
• Option C: If apple maggots only mate on their feeding trees, those on apple trees and hawthorn trees rarely interbreed (reproductive isolation), which drives speciation. This fits.
• Option D: Similar environments mean no geographic isolation (they could still interact), so this does not explain speciation. Eliminate.

Answer:

C. Apple maggots only mate on trees they feed from, so apple maggots that feed on apple trees are reproductively isolated from those that feed on hawthorn trees.