Navigation Links
Males with elevated levels of testosterone lead shorter lives but have more success siring offspring

Comparative studies have studied testosterone levels and related them to mating systems and aggression, but very few studies have attempted to relate testosterone to fitness, that is, the combination of lifetime reproductive success and survival, in the wild or experimentally. Over nine breeding seasons, Wendy Reed (North Dakota State University) and her colleagues followed a group of dark-eyed juncos, small mountain songbirds found throughout North America. They injected males with elevated levels of testosterone and found that they had shorter lives but that they were very successful at siring more offspring ? even with females who were mated with other males.

"The surprising result was that testosterone-treated males had a higher overall fitness than control males," write the authors in a study in the May issue of American Naturalist.

This led to the question of why don't juncos naturally have higher levels of testosterone? Testosterone-treated males produced more offspring, but they were smaller, and smaller offspring had lower postfledging survival. Older, more experienced females preferred to mate with older males and realized higher reproductive success when they did so. While young males treated with testosterone increased their ability to attract older females, it resulted in poor reproductive performance.

"Although testosterone increased male fitness, as measured by lifespan and number of offspring, the extended effects on offspring and female mates were generally negative and may ultimately constrain the evolution of higher testosterone levels in males," conclude the authors.


'"/>

Source:University of Chicago Press Journals


Page: 1

Related biology news :

1. UCSD study reveals how plants respond to elevated carbon dioxide
2. New lab technique identifies high levels of pathogens in therapy pool
3. Scientists at Galileo Pharmaceuticals confirm inflammatory response linked to glucose levels
4. MERIS monitoring tracks planetary photosynthesis levels
5. High carbon dioxide levels spur Southern pines to grow more needles
6. Enzyme affects hypertension by controlling salt levels in body
7. Field tested: Grasslands wont help buffer climate change as carbon dioxide levels rise
8. Babys genes affect moms cholesterol levels
9. Salmonella bacteria use RNA to assess and adjust magnesium levels
10. Fish on acid: Hagfish cope with high levels of CO2
11. High estrogen levels associated with dementia in older men
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:3/31/2016)... 31, 2016  Genomics firm Nabsys has completed a ... Barrett Bready , M.D., who returned to the company ... technical leadership team, including Chief Technology Officer, John ... Steve Nurnberg and Vice President of Software and Informatics, ... Dr. Bready served as CEO of Nabsys ...
(Date:3/23/2016)... Massachusetts , March 23, 2016 /PRNewswire/ ... im Interesse erhöhter Sicherheit Gesichts- und Stimmerkennung ... Xura, Inc. (NASDAQ: MESG ), ... bekannt, dass das Unternehmen mit SpeechPro zusammenarbeitet, ... aus der Finanzdienstleistungsbranche, wird die Möglichkeit angeboten, ...
(Date:3/22/2016)... Ontario , PROVO and ... Newborn Screening Ontario (NSO), which operates the ... for molecular testing, and Tute Genomics and UNIConnect, ... management technology respectively, today announced the launch of a ... next-generation sequencing (NGS) testing panel. NSO ...
Breaking Biology News(10 mins):
(Date:4/28/2016)... PUNE, India , April 28, 2016 ... PT, JT, Stirling, and Brayton Cryocoolers), Service (Technical Support, ... Application, and Geography - Global Forecast to 2022", published ... to USD 2.94 Billion by 2022, at a CAGR ... Browse 70 market data Tables and 94 Figures spread ...
(Date:4/28/2016)... Conn. (PRWEB) , ... April 28, 2016 , ... ... financing and ongoing support for Connecticut's innovative, growing companies, today announced the launch ... health and financial technology (fintech) companies. , “VentureClash looks to attract ...
(Date:4/28/2016)... NY (PRWEB) , ... April 28, 2016 , ... ... has made significant investments in recruiting top industry experts, and expanding its LATAM ... which provides industry-leading tools for clients to manage their clinical trial projects. , ...
(Date:4/27/2016)... ... ... Cambridge Semantics, the leading provider of Smart Data analytic and data management ... The Silicon Review’s “20 Fastest Growing Big Data Companies of 2016.” , “From ... end users facing some of the most complex data challenges in the industry,” said ...
Breaking Biology Technology: