This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The white-tipped feathers found in many chicken breeds may look like variations of the same decorative pattern, but new research shows that they do not all share the same genetic origin. Researchers from the Texas A&M College of Veterinary Medicine and Biomedical Sciences (VMBS) found that at least three independently occurring mutations involving the same gene can produce mottling, a pigmentation pattern characterized by white feather tips.
The findings, published in Animal Genetics, provide insight into how selective breeding and human preferences have shaped the diversity seen among domestic chickens. "Mottling is a bit unusual because there are at least three different mutations causing a very similar phenotype," said Dr. Leif Andersson, a professor in the VMBS' Department of Veterinary Integrative Biosciences.
The findings show that different genetic changes can converge on the same visible trait. In this case, the three mutations arose independently and were each preserved through selective breeding. Mottling is found in chicken breeds around the world.
On chickens with otherwise black feathers, the pattern typically appears as white tips that create a spotted appearance across the bird's plumage. The pattern develops when pigment cells do not migrate normally as feathers grow. If pigment cells do not reach the end of a developing feather, its tip remains white.
Among domestic animals, a physical trait shared across multiple breeds can often be traced to a single mutation that spread as animals carrying it were bred with different populations; therefore, finding several mutations affecting the same gene was unexpected. For example, Andersson said the dominant white coloration found in commercially important chicken populations, including white Leghorns, is associated with one specific mutation. Mottling appears to have followed another evolutionary path.
Rather than descending from one original mutation, similar patterns arose independently in different groups of chickens. People then selected birds with those patterns for breeding, allowing the separate mutations to become established in multiple breeds. "These mutations occurred independently," Andersson said.
Extract — continue reading at the source.
