AP BIOLOGY

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EVOLUTION

THE ORIGIN OF LIFE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
During drought years on the Galapagos, small, easily eaten seeds become rare leaving only large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, then what should one expect to result from natural selection?
A
Small birds gaining larger beaks by exercising their mouth parts.
B
Small birds mutating their beak genes with the result that later-generation offspring have larger beaks.
C
Small birds anticipating the long drought and eating more to gain weight and, consequently, growing larger beaks.
D
More small-beaked birds dying than the larger-beaked birds
Explanation: 

Detailed explanation-1: -They famously evolved to have different beaks which are suited to different food types such as large seeds and invertebrates, allowing them to occupy different niches.

Detailed explanation-2: -What are two ways the decrease in seed availability will affect the population of birds on the island? The trait for large beaks will be passed on to future generations through natural selection. & The population of birds with large beaks will increase on the island.

Detailed explanation-3: -The most common beak depth of the initial population (red bars) was 8.8 mm. A very small proportion of individuals with this beak depth survived the drought. More than half of the initial finch population died during the drought. The most common beak depth of the surviving population (black bars) was 10.3 mm.

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