British Land Snails Are an Example of Disruptive Selection

question 40

Multiple Choice

British land snails are an example of disruptive selection. In the grassy fields, the light-banded snails escape bird predators. In the darker forest, the dark snails survive and the light-banded snails are eaten. The different colored snails have the opportunity to interact and breed across the British landscape. Why doesn't this "disruptive selection" eventually lead to two separate species?

• A) There is no reproductive isolation to prevent gene flow.
• B) They are already two separate species, and the intermediate forms are hybrids.
• C) The color forms are probably not genetically determined.
• D) There must be some unknown factor producing an equal stabilizing selection "to hold the species together."
• E) This will result in the formation of two species if given long enough time.

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Definitions:

Monthly Compounded

Monthly Compounded refers to the process of applying interest to an initial sum and its previously accumulated interest at monthly intervals.

GIC

Guaranteed Investment Certificate; a Canadian investment that offers a guaranteed rate of return over a fixed period.

Maturity Value

The amount payable to an investor at the end of a fixed term investment, including principal and interest.

Monthly Compounded

A reiteration indicating that the interest accrues on a monthly basis, thereby increasing the investment or loan amount through compounding.