Speed Matters
Natural selection is a process where heritable traits that are important for survival and reproduction are passed on and where harmful traits become rarer. The organism with advantageous traits tends to mate more and pass on its genes over many generations. Researchers at UC San Diego and UC Irvine have found that sperm cell motility is important in reproductive competition in primate species, where the female mates with more than one male. Dr. Michael Berns from UC San Diego have reported that sperm cells swim much faster and with much greater force in chimpanzee and rhesus macaque species than in humans and gorillas.
Female chimps and rhesus macaques mate with several males in a social group. So for a male to pass on its genes it would be favorable if it had a faster and stronger swimming sperm cells to fertilize an egg. Researchers found the slowest swimming forces and swimming speeds belonged to gorillas where males discourage other males from mating with gorillas in their harems. So a faster sperm wouldn’t be advantageous to them. The next slowest sperm speed and force belonged to humans then the chimps. This was surprising to many scientists that the human sperm speed and force fell in between the gorillas and the chimps which raised questions if we were monogamous as we always thought we were.
Biologists have been always interested in this sperm competition for many years to test the theory if polygamous species having faster and stronger sperm speed and force in reproductive success. To test this theory it required the collaboration of biologists, physicists, and engineers to design and test the equipment. Now we have some results that support the theory that polygamous species tend to have faster and stronger swimming sperm.
Source:
Science Daily
http://www.sciencedaily.com/releases/2007/09/070925090250.htm
Posted by IamGOD (1)
posted by PWH @ 4:10 PM
3 comments
3 Comments:
This is quite an interesting post but leaves many questions unanswered. First of all I am left to wonder about the time frame that is involved with testing such a possibility. Imagine that I am faster at 100 Meter race then John. To be more accurate twice as fast. But would that account for anything if John starts an Hour before me. Thus it leads me to wonder how often do these females reproduce with the male. Is it in such a short time that having faster sperm speed would make a difference? Thus more info regarding the experiment would clarify much. Also use of punctuation, such as, commas would make the reading much smoother and more comprehensible.
Posted by,
Kirubakaran Sivagurunathan
I agree with the other comment about time of mating and number of partners being a very important variable. Perhaps there was a way that researchers could measure the individuals sperm separately and then compare the two rates. It is however interesting to find out that human sperm travels faster than chimpanzee sperm. Very good chose of topic! I would not have that sperm rate between monogamous and polygamous species would vary.
posted by,
Jessica Johnson (1)
Thanks for the great comments. Regarding the length of distance the sperm traveled, they did not measure the speed over a distance. The scientists used a technique called "laser tweezers". Where a laser light passes through a cell and effectively traps the cell and holds it from moving, the brighter the laser the more firmly it is held. So a sperm traveling at a different speed would require a brighter laser light. From a software developed in the lab they determined the speed of the sperm by the brightness of the laser used to trap it and hold it in place.
And the whole point of the experiment was to see if males who mate with more than one female will have faster sperm than males who are in monogamous relationship. So far these preliminary results support the hypothesis that the males who are in monogamous relationship tend to have slower swimming sperm compared to males in polygamous relationships.
Posted by,
IamGOD (1)
Post a Comment
<< Home