Sex chromosomes complex history in primates

Just a quick mention of what seems to be an important piece of research in the evolution of sex chromosomes in humans and primates in general. The main finding being the existence of a number of evolutionary gene conversions (transference between the X and Y chromosomes, in either direction).

Mineyo Iwase et al. Frequent gene conversion events between the X and Y homologous chromosomal regions in primates. BMC Evolutionary Biology 2010. doi:10.1186/1471-2148-10-225. Open access.


Conclusion

Gene conversion events between the X and Y homologous regions have been suggested, mainly in humans. Here, we found frequent gene conversions in the evolutionary course of primates. An insertion of a LINE element at the proximal end of the region may be a cause for these frequent conversions. This gene conversion in humans may also be one of the genetic causes of Kallmann syndrome.

Polyamory prevents extinction

... in fruit flies at least.

Tom A.R. Price et al, Polyandry Prevents Extinction. Current Biology, 2010.

There's also an article at Science Daily.

There seems to be a sex-ratio distortion (SR) X chromosome among some males that kills all the Y chromosome sperm before it can fertilize the egg, hence tending to produce an all-female offspring. By mating with various males, females prevent that this SR chromosome can become dominant up to the point of becoming a female-only population bound to extinction.

From the paper:

SR is a naturally occurring X chromosome meiotic driver that kills the Y chromosome-bearing sperm of male carriers [9,17]. SR therefore results in all-female broods and is inherited by all of the offspring of females that mate with male carriers [18,19]. This transmission advantage allows SR to spread through populations. However, the loss of half of the sperm produced by SR carriers makes them poor sperm competitors, with SR males...

Fruit fly populations in which females were forced by researchers (who acted as some sort of religious police, like in Saudi Arabia) to mate only with one male each, ended up after just 15 generations too crowded with this SR chromosome and five out of twelve (almost 50%) went extinct. Instead the control populations where free mating was allowed, remained healthy and kept the SR chromosome under control.

This seems to have implications beyond Drosophila pseudoobscura, the species used in this research, because both the "selfish" SR chromosome and the existence of promiscuity seem to be widespread through the animal kingdom.

It is quite curious how selfish genes, or in this case full chromosomes, do seem to exist but nevertheless they are not advantageous to their carriers. It is also curious how a mere drive in favor of diversity, such as promiscuity, helps to keep such genetic nuisances under control.

Is there a G-spot?

Debate rages on the issue... at least at El Reg, where they seem to find it quite amusing.

While early last month a research by King's College's fellows demonstrated that the G-spot is nothing but "a figment of women's imagination", based on self-reporting by twins, some week later French scientists criticized the findings questioning why the G-spot should be something genetic. These criticisms were made at the G-Day conference, whose organizer, Sylvain Moumain suggested that, while the G-spot exists in some 60% of women, the British are just unable to find it. In the words of gynecologist Odile Buisson:

I don't want to stigmatise at all but I think the Protestant, liberal, Anglo-Saxon character means you are very pragmatic. There has to be a cause for everything, a gene for everything. It's totalitarian.

The debate seems to be far from closed.