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:
(Date:9/18/2014)... happy-go-lucky characters, so you might expect that most would ... fact some dogs are distinctly more pessimistic than others, ... "This research is exciting because it measures positive and ... offers researchers and dog owners an insight into the ... Melissa Starling, from the Faculty of Veterinary Science. Her ...
(Date:9/18/2014)... Elsevier, a world-leading provider of scientific, technical ... Australasian Research Management Society (ARMS), recognized the academic ... 5th Scopus Young Researcher of the Year Awards. ... the National Convention Centre and in conjunction with ... guests representing Australia,s and New Zealand,s scientific community. ...
(Date:9/18/2014)... New research has found clownfish larvae can swim up to ... better able to cope with environmental change. , Clownfish spend ... anemone but as babies they must wander the open ocean, ... of Excellence for Coral Reef Studies (Coral CoE) at James ... they go, but now we,ve been given a rare glimpse ...
Breaking Biology News(10 mins):Dogs can be pessimists too 2Dogs can be pessimists too 3Elsevier and Australasian Research Management Society award scientists at Scopus ceremony 2Nemo's epic journey to find a new home 2
... structure and operating procedures of a powerful anti-bacterial ... antibiotics. In research published in the ... USA, scientists from Monash University, The Rockefeller University ... bacteriophage lysin, PlyC, kills bacteria that cause infections ...
... to train horses have raged for centuries. Two years ... ban the practice of hyperflexion as a result of a ... the animals unnecessary discomfort. The FEI did make a ... what it termed "low, deep and round" (LDR), which essentially ...
... /PRNewswire-Asia/ -- China Botanic Pharmaceutical Inc. (NYSE AMEX: ... developer, manufacturer and distributor of botanical products, bio-pharmaceuticals and ... the Company was recently granted a new patent (Patent ... Extraction Method. The new patent grant followed ...
Cached Biology News:New recruits in the fight against disease 2Bend or stretch? How stressful is hyperflexion of horses' necks? 2China Botanic Receives Patent on its Schisandra Lignin Extraction Method 2China Botanic Receives Patent on its Schisandra Lignin Extraction Method 3
(Date:9/19/2014)... , September 19, 2014 ... 53rd European Society for Paediatric Endocrinology (ESPE) Meeting  ... science and medical research in the field of growth  ... KGaA, Darmstadt, Germany , today announced ... (GGI) for 2014. The awards were announced during a ...
(Date:9/18/2014)... , Sept. 18, 2014 About POCT ... is performed outside a clinical laboratory. It helps ... administrating appropriate treatments and medication. POCT is gaining ... of lifestyle diseases such as diabetes, heart disease, ... POCT devices are standardized to minimize errors during ...
(Date:9/18/2014)... 18, 2014 ... ) has announced the addition of ... Strategic Business Report" report to ... report analyzes the worldwide markets for ... the following Product Segments: Polymeric Materials, ...
(Date:9/18/2014)... 2014 Research and Markets ... N-acetylcysteine Industry Report 2014" report to their ... Report 2014 is a professional and in-depth study ... industry. The report provides a basic ... and industry chain structure. The N-acetylcysteine market analysis ...
Breaking Biology Technology:EMD Serono Awards Grant for Growth Innovation (GGI) for the First Time 2EMD Serono Awards Grant for Growth Innovation (GGI) for the First Time 3POCT Market in China 2014-2018 2Biocompatible Materials - Global Strategic Business Report 2014 2Biocompatible Materials - Global Strategic Business Report 2014 3Global N-acetylcysteine Industry Report 2014 2
... Gunther von Hagens, BODY WORLDS 2:,The Original ... the Maryland,Science Center this Saturday, February 2nd. The ... Three Pound Gem, a special feature on,the brain., ... specimens, including,whole bodies, healthy and unhealthy organs, body ...
... Dr. Pollard Brings the Highest Level of Clinical ... Feb. 1 Genetic,Immunity(R), a US/Hungarian clinical-stage biopharmaceutical ... patented,immunotherapeutic platform technology, announced that it has appointed,Richard ... Dr. Pollard has been a leader in HIV/AIDS ...
... FOLD ), today announced that John F. Crowley, ... at the Merrill,Lynch Global Pharmaceutical, Biotechnology & Medical Device ... at 11:40 am (Eastern Standard,Time) at the Grand Hyatt ... may be accessed by visiting,Amicus, website at http://www.amicustherapeutics.com ...
Cached Biology Technology:Maryland Science Center Unveils Anatomical Exhibition, Body Worlds 2, on Saturday, February 2 2Genetic Immunity Announces the Appointment of Richard B. Pollard, M.D. as Chief Medical Officer 2Genetic Immunity Announces the Appointment of Richard B. Pollard, M.D. as Chief Medical Officer 3Amicus Therapeutics to Present at the Merrill Lynch Global Pharmaceutical, Biotechnology & Medical Device Conference 2Amicus Therapeutics to Present at the Merrill Lynch Global Pharmaceutical, Biotechnology & Medical Device Conference 3
... is a new product number, ... product number. If showing no ... the old Sigma-Aldrich number (Z71,518-2) ... assistance. Material: cap polystyrene ...
... This CLS number is a ... match Cornings product number. If showing ... the old Sigma-Aldrich number (Z71,517-4) or ... Material: cap polystyrene (expanded surface, easy ...
Formula variant: With macro- and micronutrients. Physical Form: powder Suitab tst: plant cell culture tested...
BD Falcon 850 cm Smooth-surface TufRol Roller Bottle, tissue-culture treated polystyrene, blow-molded one-piece design, with easy on/off non-vented cap. (2/sp, 20/ca) Packaging: 2 / pack, 20 /...
Biology Products: