Size matters, and bigger is always better, at least when it comes to what roosters want when looking at possible mates.
New research published in the journal PLoS Genetics suggests that roosters select the girl with the largest hairdo, or “comb.”
The scientists, from LinkÃ¶ping Universitet, say that the larger the comb of a hen, the bigger dose of sperm she will receive from the rooster, which leads to more eggs.
Domestic hens have larger combs, as well as denser bones, when compared to wild hens. According to the research, this feature can be changed through human manipulation.
The scientists say that the greater the bone mass a hen has, the more eggs she is able to lay. They have spotted a clear correlation between comb size and bone mass in chickens from a cross between red jungle fowl and domestic chicken.
After spotting this correlation, the team set up a study to determine where these chickens were crossed for several generations, allowing them to “map” the functions of individual genes.
After the eighth generation, the team found an area that had a strong effect on the weight of the comb, as well as bone mass and fertility.
The genetic variation has gradually decreased over the course of domestication, according to the findings.