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However, a closer study of the genius imposed by such “brood parasitism” changes the perspective. To achieve its goals, the cuckoo must discreetly lay eggs almost identical to those of its host and deceive its vigilance.
He achieves it masterfully. It can imitate the cry of a predator to temporarily frighten its target. Lay eggs at record speed. Reproduce the shape, the color, the very patterns of the shells, like a forger with a master’s canvas.
A feat all the more remarkable given that the legitimate owner of the nest has no interest in providing shelter and shelter. Evolution will therefore provide it with “countermeasures” that will enable it to detect the intruder.
IN article published on Monday, May 30 in the magazine Science, an international team has just shown how this “arms race,” as biologists call it, leads cuckoos to evolve faster than other birds. Even better, researchers have found that this parasitism promotes speciation, in other words the emergence of new species.
This question has always troubled biologists. How were these millions of species that inhabit our planet born? Darwin partly answered this.
Very simply put: the need to escape a predator, to reach prey, or even to improve one’s reproductive success, in each species leads to the selection of certain favorable mutations among all those that chance produces in each generation.
As long as the population is divided into two parts by an external event, especially the appearance of an ecological obstacle (river, bay, disappearance of forest, etc.), the two subgroups will continue the process, each on its own side, and irreparably diverge.
But it happens that two species appear in the same territory. Would parasitism play a role in history?
Egg and chicken imitation
To understand this, Australian and British researchers began tracking birds of the genus Chrysococcix, those which the English language, in its penchant for colorful names, calls bronze cuckoos.
“The crown jewels of the cowardly worldinsists Naomi Langmore, of the Australian National University in Sydney. The smallest and most beautiful, with its iridescent green feathers. » And masters of parasitism.
A professor of evolutionary ecology had already been observing them for years when she noticed that the bird, not satisfied with copying its host’s eggs, also imitated its chicks.
“Skin color, mouth, number of feathers, cries… each cuckoo reproduces them with extreme precision,” she continues.
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