Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

X-Effect: Female Chromosome Confirmed a Prime Driver of Speciation

19.10.2007
Researchers at the University of Rochester believe they have just confirmed a controversial theory of evolution. The X chromosome is a strikingly powerful force in the origin of new species.

Biologists have argued for years whether the X chromosome—the female chromosome in most animals—plays a special role in the process of speciation. In a new study in the journal PLoS Biology, Daven Presgraves, professor of biology at the University of Rochester, has confirmed that the X chromosome is indeed heavily influential—and the reason may be nothing like what biologists expected.

When one species splits into two, interbreeding between the two daughter species is much more likely to produce infertile hybrids when the species exchange X chromosomes than when they exchange any other chromosomes, says Presgraves. The process, dubbed the "large X-effect," acts as a wedge between the two newly formed species, pushing them onto divergent evolutionary paths.

Over the course of a year, Presgraves and research associate J. P. Masly interbred fruit flies for 15 generations. The team painstakingly substituted individual genes of one fly species with the genes of a closely related species, and tracked which genes caused infertility in hybrids. The Rochester team showed that 60 percent of X-chromosome genes cause infertility in hybrid males—far higher than the 18 percent for all the non-sex chromosomes.

"There is no more debate," says Presgraves. "The large X-effect is real."

But in solving one mystery, the findings give rise to another.

Scientists expect evolutionary changes in DNA to accumulate in random locations across a genome, but Presgraves instead found that most changes causing hybrid infertility cluster inexplicably on the X chromosome.

Presgraves is now looking into why the X is a hotspot for "speciation genes," that prevent genetic exchanges between closely related species.

The traditional notion of the large X-effect is that the X chromosome is simply "exposed," meaning its complement, the Y chromosome, doesn't have the information needed to mask the effects of changes on the X. We inherit a set of chromosomes from each parent with each chromosome acting as a sort of backup for its complement. It's a bit like cross-referencing two encyclopedias for errors, says Presgraves. In the case of X and Y, however, it's like trying to cross-reference an encyclopedia with a pamphlet.

But Presgraves believes it's not a simple case of the X chromosome being exposed. He believes there's something special about the X. Somehow, it attracts genes that disrupt the creation of sperm in hybrid males—the main cause of the hybrid's infertility, he says.

"When I look at this, I think the X is not behaving normally during spermatogenesis (sperm creation)," says Presgraves. "I think it may be that in the production of sperm, when the fly's genome is shut down and compacted to fit into the sperm head, the X is not shutting down and is wrecking the process."

Presgraves is planning new tests to see if the X is, in fact, refusing to shut down when it should.

If the process that controls normal X inactivation during spermatogenesis is particularly susceptible to evolutionary change, says Presgraves, then it may be largely responsible for the X chromosome's unusually prominent role in the origin of new species.

Jonathan Sherwood | EurekAlert!
Further information:
http://www.rochester.edu

Further reports about: HYBRID Presgraves X chromosome infertility species sperm

More articles from Life Sciences:

nachricht Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Self-illuminating pixels for a new display generation

22.05.2018 | Trade Fair News

Embryonic development: How do limbs develop from cells?

22.05.2018 | Life Sciences

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>