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Why birds have colored eggs
Especially the color of the egg shell can not only serve the purpose of masking, but also to exert a strong influence on the embryonic development of the embryo, passing some of the light wave and filtering out others.
If you want to witness one of the most bustling and multi-year scientific debate, just open the fridge and look at the usual eggs. A hundred years zoologists are unable to come to a common opinion, why there is such a variety of colors eggshell.
The first discussion on this topic emerged in the second half of the nineteenth century. Then discussed the causes of external and internal causes: there is a coloring of the shell protection from predators, or it somehow affects the formation of the embryo — for example, protects it from harmful radiation? Won the "external" point of view, about the influence of colors of the shell on the health of the embryo long forgotten. But the researchers began to Refine their hypotheses, according to which the coloration of the eggs was protecting the future offspring from external threats. Besides that, the colors masked the eggs from the eyes of a predator, she was intended to demonstrate "NewConnect" content, as well as to help parents to distinguish their eggs from the nest eggs of the parasite. According to recent theory, the colour of the shell has evolved due to the constant "arms race" between normal birds and different "cuckoo": the more the female parasite egg was like an egg of some other kind, the harder this kind of tried to change the color of your walls.
We cannot say that the second point of view is completely rejected. It was considered that the coloration of the shell allows you to hold the heat and to save the life of the embryo if the egg has suddenly appeared for a long time unattended. But still, according to ornithologists from the Australian University of Adelaide the role of "internal" factors in the formation of character coloring eggs all this time was seriously underestimated. In his article published in the Journal of Avian Biology, they put forward seven reasons why the color of the eggshell could be very critical for the embryo.
For starters, the pigments of the shell are really able to filter out harmful radiation. But at the same time light can be simply necessary for the formation of the embryo; it is known that even black eggs ostrich EMU miss some fraction of the light. Colouring on one end of the egg may be very different from those of — and this means that the difference in the resulting radiation effect on some processes of individual development: for example, pushing of cells at one pole to a more intensive division or initiates their movement. It may be so that light waves of a certain length simply accelerate the development of the chick, and thereby help him to escape from a predator, the chick hatches, the sooner it will grow and the less chance the predator to reach it. Different color can determine the time of appearance of juveniles to light: for example, to help all hatch at the same time or, conversely, to set a certain time period. For example, gulls are one of the three eggs in the clutch are always darker than the other two.
Different pigmentation of the shell can "teach" the future of the bird to distinguish light from darkness, to set circadian rhythms in the embryo, stimulate the molecular processes of DNA repair and even to influence the formation of its own microflora. Pigmentation of the shell may be different, for example, rainy or dry summer; in other words, birds, changing the color of the eggs, can "on the fly" to adapt to the geographical and seasonal linear features.
All this in no way refutes the "camouflage" theory of the color of the shell, but only indicates that internal fetal causes may be equally important. However, before proceeding to a thorough test each of the hypotheses, check whether the number under the shell of light varies in eggs of different species of birds. After all, even if it's still there a little bit of important experimental data.
Source: /users/104
If you want to witness one of the most bustling and multi-year scientific debate, just open the fridge and look at the usual eggs. A hundred years zoologists are unable to come to a common opinion, why there is such a variety of colors eggshell.
The first discussion on this topic emerged in the second half of the nineteenth century. Then discussed the causes of external and internal causes: there is a coloring of the shell protection from predators, or it somehow affects the formation of the embryo — for example, protects it from harmful radiation? Won the "external" point of view, about the influence of colors of the shell on the health of the embryo long forgotten. But the researchers began to Refine their hypotheses, according to which the coloration of the eggs was protecting the future offspring from external threats. Besides that, the colors masked the eggs from the eyes of a predator, she was intended to demonstrate "NewConnect" content, as well as to help parents to distinguish their eggs from the nest eggs of the parasite. According to recent theory, the colour of the shell has evolved due to the constant "arms race" between normal birds and different "cuckoo": the more the female parasite egg was like an egg of some other kind, the harder this kind of tried to change the color of your walls.
We cannot say that the second point of view is completely rejected. It was considered that the coloration of the shell allows you to hold the heat and to save the life of the embryo if the egg has suddenly appeared for a long time unattended. But still, according to ornithologists from the Australian University of Adelaide the role of "internal" factors in the formation of character coloring eggs all this time was seriously underestimated. In his article published in the Journal of Avian Biology, they put forward seven reasons why the color of the eggshell could be very critical for the embryo.
For starters, the pigments of the shell are really able to filter out harmful radiation. But at the same time light can be simply necessary for the formation of the embryo; it is known that even black eggs ostrich EMU miss some fraction of the light. Colouring on one end of the egg may be very different from those of — and this means that the difference in the resulting radiation effect on some processes of individual development: for example, pushing of cells at one pole to a more intensive division or initiates their movement. It may be so that light waves of a certain length simply accelerate the development of the chick, and thereby help him to escape from a predator, the chick hatches, the sooner it will grow and the less chance the predator to reach it. Different color can determine the time of appearance of juveniles to light: for example, to help all hatch at the same time or, conversely, to set a certain time period. For example, gulls are one of the three eggs in the clutch are always darker than the other two.
Different pigmentation of the shell can "teach" the future of the bird to distinguish light from darkness, to set circadian rhythms in the embryo, stimulate the molecular processes of DNA repair and even to influence the formation of its own microflora. Pigmentation of the shell may be different, for example, rainy or dry summer; in other words, birds, changing the color of the eggs, can "on the fly" to adapt to the geographical and seasonal linear features.
All this in no way refutes the "camouflage" theory of the color of the shell, but only indicates that internal fetal causes may be equally important. However, before proceeding to a thorough test each of the hypotheses, check whether the number under the shell of light varies in eggs of different species of birds. After all, even if it's still there a little bit of important experimental data.
Source: /users/104
