Featured Research

from universities, journals, and other organizations

For the rooster, size matters: How size of hen's comb is linked to ability to lay more eggs

Date:
September 4, 2012
Source:
Linköping Universitet
Summary:
A lone rooster sees a lot of all the hens in the flock, but the hen with the largest comb gets a bigger dose of sperm -- and thus more chicks. Researchers in Sweden have now shown how the size of a hen's comb is bound up with the ability to lay more eggs.

Three eighth generation advanced intercross siblings, demonstrating the extreme variation present in the cross.
Credit: Photo by Dominic Wright

A lone rooster sees a lot of all the hens in the flock, but the hen with the largest comb gets a bigger dose of sperm -- and thus more chicks. This sounds natural, but behind all this is humanity's hunger for eggs.

For thousands of years, people have tinkered with the development of domestic chickens. Through selective breeding for a few characteristics such as large muscle mass and increased egg-laying, we have at the same time caused numerous other radical changes in appearance and behaviour. A research group at Linköping University in Sweden has now shown how the size of a hen's comb is bound up with the ability to lay more eggs. The results have been presented in the scientific journal PLoS Genetics.

Compared with the original wild jungle hen, domestic hens have larger combs as well as denser bones. This influences egg-laying, as the hen's bone tissues provide calcium for the eggshells. The greater the bone mass, the more eggs she can lay.

After having spotted a clear correlation between comb size and bone mass in chickens from a cross between red junglefowl and domestic chicken, the research group -- under the leadership of evolutionary geneticist Dominic Wright -- set up a study where such chickens were crossed for several generations. In this way the genome was split up into smaller and smaller regions, which allowed the "mapping" of the functions of individual genes.

In the eighth generation, the researchers found an area that had a strong effect on the weight of the comb -- but also on bone mass and fertility.

The genetic variation has gradually decreased over the course of domestication. In domestic chickens there are now some 40 known small regions with stable genes that potentially govern their typical "domestic" characteristics. LiU researchers have now discovered two "pleiotropic" genes: two genes connected to each other that influence several characteristics simultaneously. By regulating the production of cartilage, they influence combs (which consist of cartilage throughout) as well as bone growth (where cartilage is the base material) and, ultimately, egg production.

"The original hens have smaller combs, thinner legs, and lay fewer eggs. When people bred for the characteristic of laying many eggs, the comb grew automatically," Dominic Wright says.

In nature, the comb is an example of a sexual ornament. Individuals -- often males -- with the most impressive ornaments are favoured by females, thereby obtaining more numerous offspring than their competitors. In domesticated animals, sexual selection -- like natural selection -- has lost its role, as it was humans who determine breeding.


Story Source:

The above story is based on materials provided by Linköping Universitet. Note: Materials may be edited for content and length.


Journal Reference:

  1. Martin Johnsson, Ida Gustafson, Carl-Johan Rubin, Anna-Stina Sahlqvist, Kenneth B. Jonsson, Susanne Kerje, Olov Ekwall, Olle Kämpe, Leif Andersson, Per Jensen, Dominic Wright. A Sexual Ornament in Chickens Is Affected by Pleiotropic Alleles at HAO1 and BMP2, Selected during Domestication. PLoS Genetics, 2012; 8 (8): e1002914 DOI: 10.1371/journal.pgen.1002914

Cite This Page:

Linköping Universitet. "For the rooster, size matters: How size of hen's comb is linked to ability to lay more eggs." ScienceDaily. ScienceDaily, 4 September 2012. <www.sciencedaily.com/releases/2012/09/120904100041.htm>.
Linköping Universitet. (2012, September 4). For the rooster, size matters: How size of hen's comb is linked to ability to lay more eggs. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2012/09/120904100041.htm
Linköping Universitet. "For the rooster, size matters: How size of hen's comb is linked to ability to lay more eggs." ScienceDaily. www.sciencedaily.com/releases/2012/09/120904100041.htm (accessed September 2, 2014).

Share This




More Plants & Animals News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Snack Attack: Study Says Action Movies Make You Snack More

Snack Attack: Study Says Action Movies Make You Snack More

Newsy (Sep. 2, 2014) — You're more likely to gain weight while watching action flicks than you are watching other types of programming, says a new study published in JAMA. Video provided by Newsy
Powered by NewsLook.com
Get A Mortgage, Receive A Cat — Only In Russia

Get A Mortgage, Receive A Cat — Only In Russia

Newsy (Sep. 2, 2014) — The incentive is in keeping with a Russian superstition that it's good luck for a cat to be the first to cross the threshold of a new home. Video provided by Newsy
Powered by NewsLook.com
U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) — The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Sharks Off the Menu and on the Tourist Trail in Palau

Sharks Off the Menu and on the Tourist Trail in Palau

AFP (Sep. 2, 2014) — Tourists in Palau clamour to dive with sharks thanks to a pioneering conservation initiative -- as the island nation plans to completely ban commercial fishing in its vast ocean territory. 01:15 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins