Gallus gallus is a domesticated bird known as the chicken which is believed to have first bred in southeast Asia. Ever since Darwin, we have known that the chicken originated in southeast Asia, although the exact details of which one or more of several possible jungle fowls is the primal form has been debated. The idea that the existence of chicken is the contribution of more than one wild species has been on the table for a very long time. Notice the yellow legs on this chicken. If you pluck out the feathers, you will find the skin to be yellow as well. But if you go find, say, a crow, and pluck its feathers, it will be greyish in colour. The gist of this is that some birds are yellow while some are not.
There is a gene that is expressed in certain tissues that produces an enzyme that cleaves the carotenoid molecules that provide the yellow colour. You get a yellow bird (depending on other factors we shall ignore) if there is no functional copy of this gene. In short, it is confirmed by the new research that previously thought the red jungle fowl, Gallus gallus, is ancestral to the modern chicken, as Darwin suspected. But this research also suggests that another bird, the grey jungle fowl, Gallus sonneratii, also contributed to the chicken's genome, providing the yellow color we see on this chicken's legs.
In this sub category you can download free PNG images: Chicken Food. In this category "Chicken" we have 108 free PNG images with transparent background.
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