Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mutant Gene Responsible for Pigeons' Head Crests

01.02.2013
Decoded genome reveals secrets of pigeon traits and origins

Scientists have decoded the genetic blueprint of the rock pigeon, unlocking secrets about pigeons' Middle East origins, feral pigeons' kinship with escaped racing birds and how mutations give pigeons traits like feather head crests.


Head ornamentation called a shell crest is seen on this English trumpeter rock pigeon.

"Birds are a huge part of life on Earth, but we know surprisingly little about their genetics," says Michael Shapiro, one of the study's two principal authors and a biologist at the University of Utah.

In the new study, "we've shown a way forward to find the genetic basis of traits--the molecular mechanisms controlling animal diversity in pigeons," he says. "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."

The findings appear in a paper published this week in the online journal Science Express.

Shapiro conducted the research with Jun Wang of China's BGI-Shenzhen (formerly Beijing Genomics Institute) and other scientists from BGI, the University of Utah, Denmark's University of Copenhagen and the University of Texas M.D. Anderson Cancer Center in Houston.

"The research identified the genes contributing to variation in the avian head crest, using the domesticated pigeons that so fascinated and inspired Charles Darwin in developing his theory of natural selection," says George Gilchrist, program director in the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research. "This finding illustrates the power of comparative genomics."

Pigeons were domesticated some 5,000 years ago in the Mediterranean region. Key results of this study include sequencing of the genome of the rock pigeon Columba livia, which is among the most common bird species.

There are some 350 breeds of rock pigeons--all with different sizes, shapes, colors, color patterns, beaks, bone structure, vocalizations and arrangements of feathers on the feet and head--including head crests in shapes known as hoods, manes, shells and peaks.

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 Elizabethan collar."

The researchers found strong evidence that the EphB2 (Ephrin receptor B2) gene acts as an on-off switch to create a head crest when mutant, and no head crest when normal.

They also showed that the mutation and related changes in nearby DNA are shared by all crested pigeons, so the trait evolved just once and was spread to numerous pigeon breeds by breeders.

Full or partial genetic sequences were analyzed for 69 crested birds from 22 breeds, and 95 uncrested birds from 57 breeds. The biologists found a perfect association between the mutant gene and the presence of head crests.

They also showed that while the head crest trait becomes apparent in juvenile pigeons, the mutant gene affects pigeon embryos by reversing the direction of feather buds--from which feathers later grow--at a molecular level.

Other genetic factors determine what kind of head crest each pigeon develops: shell, peak, mane or hood.

Tracking the origins of pigeons
A 2012 study by Shapiro provided limited evidence of pigeons' origins in the Middle East and some breeds' origins in India and indicated kinship between common feral or free-living, city pigeons and escaped racing pigeons.

In the new study, "we included some different breeds that we didn't include in the last analysis," Shapiro says. "Some of those breeds only left the Middle East in the last few decades. They've probably been there for hundreds if not thousands of years. If we find that other breeds are closely related to them, then we can infer those other breeds probably also came from the Middle East."

The scientists found that the owl breeds--pigeon breeds with very short beaks that are popular with breeders--likely came from the Middle East. They're closely related to breeds from Syria, Lebanon and Egypt.

The research also uncovered a shared genetic heritage between breeds from Iran and breeds likely from India, consistent with historical records of trade routes between those regions. People were not only sharing goods along those routes, but probably also interbreeding their pigeons.

As for the idea that free-living pigeons descended from escaped racing pigeons, Shapiro says his 2012 study was based on "relatively few genetic markers scattered throughout the genome. We now have stronger evidence based on 1.5 million markers, confirming the previous result with much better data."

The scientists analyzed partial genomes of two feral pigeons: one from a U.S. Interstate-15 overpass in Utah's Salt Lake Valley, the other from Lake Anna in Virginia.

"Despite being separated by 1,000 miles, they are genetically very similar to each other and to the racing homer breed," Shapiro says.

"Darwin used this striking example to communicate how natural selection works," he says. "Now we can get to the DNA-level changes that are responsible for some of the diversity that intrigued Darwin 150 years ago."

The study's co-authors from the University of Utah include Yandell, Eric Domyan, Zev Kronenberg, Michael Campbell, Anna Vickery and Sydney Stringham; Chad Huff is a co-author from the University of Texas.

The study was also funded by the Burroughs Wellcome Fund, the University of Utah Research Foundation, the National Institutes of Health and the Danish National Research Foundation.

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Lee Siegel, University of Utah (801) 581-8993 lee.siegel@utah.edu
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Life Sciences:

nachricht The first genome of a coral reef fish
29.09.2016 | King Abdullah University of Science and Technology

nachricht New switch decides between genome repair and death of cells
27.09.2016 | University of Cologne - Universität zu Köln

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

 
Latest News

New Multiferroic Materials from Building Blocks

29.09.2016 | Materials Sciences

Silicon Fluorescent Material Developed Enabling Observations under a Bright “Biological Optical Window”

29.09.2016 | Materials Sciences

X-shape Bio-inspired Structures

29.09.2016 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>