The bird, Parus major, is commonly found in man-made habitats. During the summer these birds primarily feed on insects, and in the winter, when insects are scarce, they forage in gardens and bird feeders for seeds, nuts, and berries. Recently, climate change has led to a decrease in food available from gardens, and scientists have observed that the average beak length of the birds has increased.
Which of the following best explains the directional shift in beak length in these birds?A. Longer beaks allow the birds to better fend off predators.B. Longer beaks increase the fitness of the birds in wild habitats.C. Longer beaks allow the birds to better access seeds in bird feeders.D. Longer beaks decrease the fitness of the birds in wild habitats.

Since climate change makes more difficult for "Parus major" birds to feed from its primary source of food in gardens, the birds are adapting to access their second source of food, which is the bird feeder. Longer beaks allow the birds to better access seeds in bird feeders, therefore, the birds are developing longer beaks in order to adapt to their new conditions.

aliasger2709 aliasger2709 · Answer 2 · 2022-01-10T13:18:31+01:00

In genetics, the population or the community having better traits over another are favoured and selected this negative selection of one community is called directional shift.

The directional shift in beak length can be best defined by long beaks as they permit the birds for adequate access to the seeds in feeders.

The shift can be explained as:

Climatic alteration has affected the food source of the bird and had led the bird to change its feeding habits to survive.

The bird feeder was the secondary source of food for the birds as their primary source from the garden was getting depleted therefore, longer beaks allowed them to access the feeder to get grains and seeds.

Therefore, option C is correct.

Learn more about adaptation here:

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