In Swiss starlings, genotypes that lead to a clutch size (the number of eggs a bird lays) of up to five will have more surviving young than birds of the same species that lay a larger or smaller number of eggs. Which type of selection would most likely occur

Variation of clutch sizes of birds is described below.

Explanation:

Clutch size refers to the number of eggs laid in a single brood by a nesting pair of birds. The numbers laid by a particular species in a given location are usually well defined by evolutionary trade-offs with many factors involved, including resource availability and energetic constraints.A clutch of eggs is the total number of eggs laid in one nesting attempt. Clutch sizes vary within and among species. For example, a Laysan Albatross lays only one egg per clutch; an Adelie Penguin typically lays two. Red-tailed Hawks often lay 3 eggs; whereas a Wood Duck may lay 7–14 eggs per clutch. Virtually all songbirds lay one egg per day, usually in the early morning, until the clutch is complete. In some larger species the female will lay an egg only once every 2–3 days.Bobwhite quails lay an average of 12 eggs per clutch, though they can lay as many as 20; they only lay one egg a day. They lay a large number of eggs because they often lose their nests.However, the reasons why one species of bird may lay one egg and another 10 are more complex because clutch sizes can vary widely between closely related species due to variations in their environment, nutrition, health and predation. ... We show that increased environmental variation causes birds to lay larger clutches.When clutch sizes within populations are censused and then the number of young successfully reared is determined, it often turns out that the average clutch size is slightly below that which produces the greatest number of successfully reared young.