2011年4月20日星期三

Best duck bills indicate sperm "Killer" (LiveScience.com)

Looking for a STD-free partner? Check the color of their invoice (if you are a mallard duck, that is). Researchers have found that the most brilliant of the bill, the most effective Mallard is their sperm to kill bacteria.

"Under the assumption that bacteria can hurt sperm, it is logical to think that men who have a better ability to kill bacteria could suffer less of that bacteria is the damage of sperm," said Rowe, Melissah, University of Oslo, Norway. "The females may be able to avoid a pathogen sexually and identify males with better sperm."

Colour of bill of the duck, which can vary from a dull olive green to a bright, yellow raincoat is a sexually selected feature, which means women prefer men with brighter invoices, making it more likely to be transmitted to offspring traits. They go for the brightest law projects, scientists believe, because the colour of signals in a certain way for a potential partner fitness or ability to produce healthy offspring.

"Researchers have shown that sexual selected strokes may be associated with health, with the quality, of semen and with parents of capacity" Rowe told LiveScience. "A female choose a male for more colorful Bill has some benefits of fitness, offspring of quality more or higher." If it did not enjoy that the preference for that quality would not evolve. ?

Super sperm

Previous work has shown that bill colour is also correlated with the speed of sperm and capacity generally best to fight infections. The Bill colour is created by carotenoids, more of these pigments, the most brilliant of the colour of the Bill.

To determine whether bill color and underlying carotenoids, are linked to the antibacterial functions of sperm Rowe and his colleagues tested the semen of a group of ducks. They measured the effectiveness with which the sperm was to kill the bacteria e. coli and s. aureus. Then, they compared the results to the brightness of the invoices of the ducks.

They found that the best bill color, better duck semen was to kill e. coli bacteria, although results for s. aureus has no comparison with the colour of the Bill. They are not certain which part of the semen gives these antibacterial properties and identification of these factors is the next project of Rowe.

E. coli is commonly found in feces. In the duck, it is often found in the reproductive tract as the Cloaca of the duck (opening of these regions as genital) is a collection spot for digestive and reproductive systems. Researchers what effect the bacteria could have on both partners, but humans and e. coli is known to be detrimental to the viability and quality of sperm.

Interestingly, even if sperm can kill second bacteria that they tested, s. aureus, this effect not associated with the colour of bill. Two antibacterial properties appear to be mitigated by different proteins, or s. aureus may not be as great a threat to the ducks.

Bacterial lambine

Sexually bacteria can have a negative impact on the two partners of duck. Bacteria can affect sperm of the male, making it less viable, and it can also make sick of the female, making it less likely to be able to take care of her offspring, but the specific effects of e. coli on mallards is unknown.

"A man with a lot of bacteria may be less able to produce high quality and the offspring of father sperm, said Rowe." "" A man who has a good ability to kill bacteria in the ejaculate may be able to defend the spermatozoa of these bacteria and probably not the decline of the same quality that other males have. ?

Because ducks were reared in captivity, it is possible that sexually selected traits pourraient were changed by the absence of the pressures of living in the wild, Aldo Poiani, of Monash University in Victoria, in Australia, said LiveScience in an email. For example, ducks must cope with diseases and predators that make life difficult wild.

The sample was relatively small, Poiani, who was not involved in the study, said, but "it is a beautiful piece of work".

The study is published today (April 12) in the journal Biology Letters.

You can follow LiveScience staff writer Jennifer Welsh on Twitter @ microbelover.


View the original article here

没有评论:

发表评论