Coloring eggs helps fight the birds nesting parasitism


17/04/2012

Cuckoo eggs can take a color eggs of those birds whose nests they throw up their. A bird eggs of the host, in turn, are able to change their color to prevent the breeding of parasitism.

Over the past 40 years, eggs laid by the two African species of birds - Cuckoo and accepted - much changed their colors, as shown by a study published in the edition of The American Naturalist. This phenomenon is associated with the development of adaptation to the female parasitism.

Cuckoo, is known to brood parasite, it lays its eggs in the nests of birds of other species, so that they grew her chicks. In Africa, cuckoo for this purpose often uses such a small bird nests belonging to the family of Tsistikolovyh as Prynne (Prinia subflava). Coloring eggs Cuckoo’s very similar to the color of the eggs passed, so that they do not distinguish between them and dumped, and cast out of their sockets. However, in the course of evolution in Prien vrabotalsya defense mechanism: the color shades of eggs varies from female to female, and most of the cuckoo does not "guess" colored eggs in a particular slot, so Prinny from time to time still "calculating" thrown up cuckoo eggs.

Two ornithologist from the University of Cambridge, Claire Spottiswoode and Martin Stevens, showed that the competitions, which are conducted privately between the cuckoo eggs which are able to mimic the eggs received and accepted, trying to resist it in every way, can become a cause of rapid changes in the color of the eggs of birds of these species.

In order to verify his observations, ornithologists have created a computer model that made it possible to evaluate all the changes marked in the color and location of spots in terms of perception of the birds themselves, the color-blind person and a better ability to see ultraviolet light. Computer modeling was confirmation that the changes in the color of the eggs occurred quite rapidly, in just 40 years, which, according to Stevens, is from an evolutionary point of view, "just a moment".

The study was a prime example of evolutionary competition between parasite and host. Terms of natural selection makes the cuckoo keep pace with the change of color of their eggs after the change of color of the eggs is adopted, which is also constantly striving to get ahead of the cuckoo.


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