Re: testosterone's positive and negative effects in evolution...

The world would have been better off if moron george bush jrs mom barbara
bush swallowed the semen.

If she did, we wouldnt be reading all this crap from fatherless faggots
James Michael Howard and the rest of the FBI transvestites in american
government.




"James Michael Howard" <jmhoward@xxxxxxxxxxxxxxxx> wrote in message
news:hr5k52dikjtcgvlo7j6qspa1ovkq7dulf5@xxxxxxxxxx

Am Nat. 2006 May;167(5):667-83. Epub 2006 Apr 5


Physiological Effects on Demography: A Long-Term Experimental Study of
Testosterone's Effects on Fitness.

Reed WL, Clark ME, Parker PG, Raouf SA, Arguedas N, Monk DS, Snajdr E,
Nolan V Jr, Ketterson ED.

Department of Biological Sciences, North Dakota State University, Fargo,
North Dakota, 58105, USA.

Understanding physiological and behavioral mechanisms underlying the
diversity of observed life-history strategies is challenging because of
difficulties in obtaining long-term measures of fitness and in relating
fitness to these mechanisms. We evaluated effects of experimentally
elevated testosterone on male fitness in a population of dark-eyed juncos
studied over nine breeding seasons using a demographic modeling approach.
Elevated levels of testosterone decreased survival rates but increased
success of producing extra-pair offspring. Higher overall fitness for
testosterone-treated males was unexpected and led us to consider indirect
effects of testosterone on offspring and females. Nest success was similar
for testosterone-treated and control males, but testosterone-treated males
produced smaller offspring, 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. Treatment
of young males increased their ability to attract older females yet
resulted in poor reproductive performance. The higher fitness of
testosterone-treated males in the absence of a comparable natural
phenotype
suggests that the natural phenotype may be constrained. If this phenotype
were to arise, the negative social effects on offspring and mates suggest
that these effects might prevent high-testosterone phenotypes from
spreading in the population.



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