Question

On an island, there are only two common trees that produce fruit for birds to eat: small fruit that require narrow beaks to open, and large fruit that require wide beaks to crack open. A thousand years after a bird species colonizes the island, you find there are two ecotypes of the bird present: a small-bodied type with a narrow beak, and a large-bodied type with a wide beak. Each bird ecotype feeds in a different tree species, and is observed to mate and nest exclusively with its own ecotype. You conclude: \bigcirc disruptive selection on habitat choice caused birds to only mate with other birds that hung out in the same tree \bigcirc selection on beak size must have become linked to a male display trait in each ecotype \bigcirc size-assortative mating evolved as a consequence of disruptive selection on body and beak size \bigcirc sympatric speciation has gone to completion and the two ecotypes are fully reproductively isolated

          On an island, there are only two common trees that produce fruit for birds to eat: small fruit
that require narrow beaks to open, and large fruit that require wide beaks to crack open. A
thousand years after a bird species colonizes the island, you find there are two ecotypes of the
bird present: a small-bodied type with a narrow beak, and a large-bodied type with a wide
beak. Each bird ecotype feeds in a different tree species, and is observed to mate and nest
exclusively with its own ecotype. You conclude:

\bigcirc disruptive selection on habitat choice caused birds to only mate with other birds that hung out in the
same tree

\bigcirc selection on beak size must have become linked to a male display trait in each ecotype

\bigcirc size-assortative mating evolved as a consequence of disruptive selection on body and beak size

\bigcirc sympatric speciation has gone to completion and the two ecotypes are fully reproductively isolated

On an island, there are only two common trees that produce fruit for birds to eat: small fruit
that require narrow beaks to open, and large fruit that require wide beaks to crack open. A
thousand years after a bird species colonizes the island, you find there are two ecotypes of the
bird present: a small-bodied type with a narrow beak, and a large-bodied type with a wide
beak. Each bird ecotype feeds in a different tree species, and is observed to mate and nest
exclusively with its own ecotype. You conclude:

◯disruptive selection on habitat choice caused birds to only mate with other birds that hung out in the
same tree

◯selection on beak size must have become linked to a male display trait in each ecotype

◯size-assortative mating evolved as a consequence of disruptive selection on body and beak size

◯sympatric speciation has gone to completion and the two ecotypes are fully reproductively isolated

Added by Kevin C.

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