evolgen: What's Up With the Y Chromosome?

Search this blog

This is evolgen

Are Deletions Deleterious?

Detecting Natural Selection

Convergent Resouces

Blogs at the Convergence Other Blogs

Journals at the Convergence

« Even More on Detecting Natural Selection | Main

What's Up With the Y Chromosome?

Category: Evolution • Genetics • Genomics • Molecular Biology • Molecular Evolution
Posted on: March 19, 2006 8:32 AM

The human Y, that is. The Science Creative Quarterly has a very thorough (ie, make sure you have some time to spare) review of the mammalian Y chromosome (focusing on the human Y). The article covers the origin and evolution of the mammalian Y and what the degeneration of the Y means for the future of human male fertility and sex determination. I should point out that the mammalian Y chromosome is an anomaly in origin and sex determination. In fact, every single sex determination system and sex chromosome system that I know of differs from all of the others in some manner. It looks like I'm going to have to write an entry on the evolutionary genetics of sex determination in everything other than mammals (because the SCQ has already covered the furry guys).

Send this entry to: Del.icio.us Spurl Ma.gnolia Digg Newsvine Reddit

TrackBacks

(TrackBack URL for this entry: http://scienceblogs.com/cgi-bin/MT/mt-tb.cgi/2966)

Man, not woman, is the second sex from My own small world
“And the LORD God caused a deep sleep to fall upon Adam, and he slept: and he took one of his ribs, and closed up the flesh instead thereof; And the rib, which the LORD God had taken from man, made he a woman, and brought her unto the man. And Adam s... Read More
Tracked on March 19, 2006 11:06 AM

Comments

(Subscribe to this post's comment feed: )

There is also an excellent review of mammlian sex chromsomes in the current issue (10th march) of 'cell' called 'Sex Chromosome Specialization and Degeneration in Mammals' by Jennifer A. Marshall Graves.

It can be downloaded for free by clicking this link:
http://www.agrf.org.au/LinkClick.aspx?link=graves+Cell+final+100306.pdf&mid=443
('save as' doesn't work for this link)

Posted by: Lukas | March 19, 2006 10:02 AM

"In fact, every single sex determination system and sex chromosome system that I know of differs from all of the others in some manner."

But they are also very similar in many ways. Sex determination systems are usually cascades of regulatory genes terminating in a final switch that makes an organism male or female. Downstream elements of the cascade are often highly conserved, but the upstream parts can vary wildly, even within species. A possible reason is that the upstream parts are vulnerable to being "hijacked" by "selfish" genetic elements that bias the sex ratio in order to gain an "unfair" transmission advantage.

Posted by: Ido | March 19, 2006 05:26 PM

Despite the diversity of sex-determining systems, Haldane's rule holds across a variety of taxa (hybrids that are the sex with two different sex chromosomes - the equivalent of X and Y - tend to have lower fitness than hybrids of the other sex). Does this suggests an underlying similarity, at least at some level?

Posted by: Jacob | March 20, 2006 12:04 AM

Good points, guys, but I was actually thinking more along the lines of the different chromosomal types of sex determination (rather than physiological/biochemical). For instance, how XY systems differ between mammals and Drosophila, as do the origins of the mammalian Y and Drosophila Ys (yes, Drosophila Y chromosomes are not homologous). Doris Bachtrog's done some cool stuff on Y degeneration in Drosophila that I could probably write about.

There are also some interesting anecdotes like how in many taxa sex is determined environmentally. Or, some organisms can change sex in the middle of their life depending on population dynamics. Or, how in birds the heterogametic sex are females. Mostly, I wanted to focus on the diversity of sex determination at the chromosomal level.

Posted by: RPM | March 20, 2006 12:17 AM

evolgen

Search this blog

Categories

Recent Posts

Recent Comments

Archives