Navigation Links
Study shows costs and benefits of testosterone in birds
Date:5/13/2010

Do nice guys finish last, or will the meek inherit the earth? A new study published in The American Naturalist suggests that, at least for birds, the right answer is somewhere in between.

Individual male birds can differ dramatically in their behavior, and this difference is often due in part to how much testosterone they produce. In many species, some males produce high testosterone and are more aggressive, while others produce lower levels and are more parental.

Testosterone and the behaviors it mediates may predict how well a male succeeds. For example, an aggressive male may be more likely to obtain high-quality territories that attract females. At the same time, aggression might pose a survival risk, because aggressive males might be more likely to engage in costly fights. These considerations suggest that hormones like testosterone might be under strong natural selection in the wild.

To test this idea, a team of researchers from Indiana University studied a common songbird, the dark-eyed junco in the Appalachian Mountains of Virginia. They tested how much testosterone a male could produce by using an injection of a hormone produced in the brain that causes the bird to increase its testosterone levels temporarily, mimicking what they do naturally when fighting with other males. The researchers then followed the birds, measuring their survival and success at reproduction, both in their own nest and those of their neighbors.

They found strong relationships between testosterone and both reproduction and survival, demonstrating that natural selection is currently acting on testosterone production in this population of juncos. The exact pattern of selection they found was surprising, however. "The males that did the best at both survival and reproduction had testosterone production very close to average," said Joel McGlothlin, the lead author of the study who is now a postdoctoral fellow at the University of Virginia. "It was bad to produce either really high or really low levels of testosterone." High-testosterone males did have one universal advantagethey were more likely to be the genetic father of the offspring raised in their nests.

These results indicate that the trade-offs that testosterone regulates are quite complex. "It's not as simple as saying testosterone is good for reproduction and bad for survival," McGlothlin said. "Testosterone seems to underlie this delicate balance between competing traits and behaviors, and the right balance might be different for different males."


'/>"/>

Contact: Kevin Stacey
kstacey@press.uchicago.edu
773-834-0386
University of Chicago Press Journals
Source:Eurekalert

Related medicine news :

1. Study finds rotavirus vaccine greatly reduces hospitalizations for acute gastroenteritis in children
2. Childhood psychological problems create long-term economic losses, study finds
3. HIRC Research Alert: New Study Identifies Best Pharmaceutical Company Account Managers and Program Offerings
4. Study demonstrates art therapys effectiveness in pediatric asthma
5. Brain Cell Study Explains Eureka Moment
6. Study Challenges Key Autism Theory
7. New study suggests sickle cell disease may affect brain function in adults
8. Once-A-Year Vitamin D Megadose Ups Fracture Risk: Study
9. Genetic Variants Tied to MS, Study Finds
10. UT Southwestern participates in nationwide study offering free lung tumor genetic testing
11. Study finds post-transplant patients off steroids have fewer cardiovascular events
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/6/2016)... ... 06, 2016 , ... Logically, spring weather, with its moderate humidity and temperatures, ... cold, dry or hot, water on the eye surface can evaporate, creating uncomfortable dry ... air. There’s only one problem, according to radio show and water advocate Sharon Kleyne: ...
(Date:5/6/2016)... ... , ... Canadian author Mark Black is a speaker, author, and life strategy coach ... world … with the help of his publisher Strategic Book Group and its subsidiary ... hospital bed waiting for a miracle: He needed a heart and double-lung transplant. From this ...
(Date:5/6/2016)... , ... May 06, 2016 , ... Yisrayl Hawkins, Pastor and Overseer at The House ... worldwide, what he has found in the Bible about helping to stop cancer. Yisrayl says ... it is his hope that the health and science industries will pay close attention and ...
(Date:5/6/2016)... ... 2016 , ... Kenneth Cochran, DSc, RN, FACHE, President/CEO of ... South announced today that Dr. Robert Menuet, Interventional Cardiologist with Cardiovascular Institute of ... Coronary Atherectomy. , This procedure involves the removal of plaque by ...
(Date:5/5/2016)... Tucson, AZ (PRWEB) , ... May 05, 2016 , ... ... more attention being paid to the impact our aging population has on communities and ... help aging adults plan for and face age-related challenges. , Aging Life Care ...
Breaking Medicine News(10 mins):
(Date:5/3/2016)... 2016 Global Insulin Needles ... 09 key companies and supported with 272 tables ... study on the current state of the Insulin ... industry including definitions, classifications, applications and industry chain ... for the international market including development history, competitive ...
(Date:5/3/2016)... May 4, 2016 Research and ... Cancer Stem Cell Therapy Market Outlook 2020" report ... ) , ,Recombinant technology has improved significantly in ... to be developed in coming years. Many cancer drugs ... stem cell therapies are also expected to be developed ...
(Date:5/3/2016)... , May 3, 2016  As a teenager, an ... rheumatic fever, which damaged his heart. He continued enjoying ... by June 2013, Shepherd,s heart was giving out and ... On June 20, 2013, the Mesa, Arizona ... Heart (TAH-t). Like a heart transplant, the SynCardia TAH-t ...
Breaking Medicine Technology: