The pigeon's genetic blueprint is among the few bird genomes sequenced so far, along with those of the chicken, turkey, zebra finch and a common parakeet known as a budgerigar or budgie. "This will give us new insights into bird evolution," Shapiro says.
Using software developed by paper co-author Mark Yandell, a geneticist at the University of Utah, the scientists revealed that a single mutation in a gene named EphB2 causes head and neck feathers to grow upward instead of downward, creating head crests.
"This same gene in humans has been implicated as a contributor to Alzheimer's disease, as well as prostate cancer and possibly other cancers," Shapiro says, noting that more than 80 of the 350 pigeon breeds have head crests, which play a role in attracting mates in many bird species.
The researchers compared the pigeon genome to those of chickens, turkeys and zebra finches. "Despite 100 million years of evolution since these bird species diverged, their genomes are very similar," Shapiro says.
A genome for the birds, a gene for head crests
The biologists assembled 1.1 billion base pairs of DNA in the rock pigeon genome; the researchers believe there are about 1.3 billion total, compared with 3 billion base pairs in the human genome. The rock pigeon's 17,300 genes compare in number with the approximately 21,000 genes in humans.
The researchers first constructed a "reference genome"--a full genetic blueprint--from a male of the pigeon breed named the Danish tumbler.
Shapiro says the study is the first to pinpoint a gene mutation responsible for a pigeon trait, in this case, head crests.
"A head crest is a series of feathers on the back of the head and neck," Shapiro says. "Some are small and pointed. Others look like a shell behind the head; some people think they look like mullets. They can be as extreme as an
|Contact: Cheryl Dybas|
National Science Foundation