Brett Smith for redOrbit.com – Your Universe Online
Using cutting edge sequencing techniques, the researchers were able to identify the genetic basis for a number of traits that identify various breeds of pigeons.
In the study, the geneticists were able to assemble 1.1 billion base pairs of DNA in the rock pigeon genome, compared with 3 billion base pairs in the human genome. They noted that the rock pigeon’s 17,300 genes compare with about 21,000 genes in our genome.
The researchers were able to compare their newly sequenced genome to that of other birds, including turkeys and zebra finches.
“Despite 100 million years of evolution since these bird species diverged, their genomes are very similar,” Shapiro said.
The researchers also set out to identify a genetic mutation that is responsible for a specific pigeon trait, namely the head crests worn most notably by the breed Old Dutch capuchine.
To identify this potential mutation, the researchers first created a “reference genome” from a male of the Danish tumbler pigeon breed.
Then, using software developed by study co-author Mark Yandell, a geneticist from the University of Utah, the scientists found that a single mutation in a gene named EphB2 was responsible for head and neck feathers to grow upward and into a head crest. According to the researchers, the study is the first to locate a gene mutation responsible for a specific pigeon trait.
“A head crest is a series of feathers on the back of the head and neck,” Shapiro said. “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 Elizabethan collar.”
According to the geneticists, the EphB2 gene acts as a switch that creates a head crest when mutated, and no head crest when it´s normal. They reached this conclusion by showing that the mutation and the associated changes to nearby DNA are shared by all crested pigeons. This also suggests that the trait evolved once and was spread via breeding as over 80 of the 350 pigeon breeds have head crests. The crests are mostly used to attract a mate.
Shapiro noted that this same gene, EphB2, also appears in the human genome.
“This same gene in humans has been implicated as a contributor to Alzheimer’s disease, as well as prostate cancer and possibly other cancers,” he said.
He added that, “we’ve shown a way forward to find the genetic basis of traits–the molecular mechanisms controlling animal diversity in pigeons.”
“Using this approach, we expect to be able to do this for other traits in pigeons, and it can be applied to other birds and many other animals as well,” Shapiro said.