Finches with larger beaks were able to eat larger seeds then their small beaked relatives when a drought deceased the number of plants that produce small seeds. The large beaked birds survived and reproduced. This is an example of which cause of evolution?

PATTERNS OF EVOLUTION

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

A	small population
B	mutations
C	natural selection
D	movement (gene flow)
E	nonrandom mating (sexual selection)

Explanation:

Detailed explanation-1: -Because the drought reduced the number of seeds and finches with bigger beaks were able to eat the larger and harder seeds so more of them survived.

Detailed explanation-2: -What was the difference in average beak size of all adults before the drought in 1977 and the average beak size of adults that survived the drought? Before the drought, the average size of adult beaks was 9.2 mm. The average beak size of adults that survived was 9.9 mm.

Detailed explanation-3: -The large ground finch evolved a large broad beak which it uses to feed on hard seeds and nuts. Woody nuts are its main food source. It forages either on the ground or in trees and bushes for its food.

Detailed explanation-4: -Figure 18.1C. 1: Finches of Daphne Major: A drought on the Galápagos island of Daphne Major in 1977 reduced the number of small seeds available to finches, causing many of the small-beaked finches to die. This caused an increase in the finches’ average beak size between 1976 and 1978.

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