Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sexual competition drives evolution of a sex-related gene

08.11.2004


In what could be termed a truly seminal discovery, researchers have shown that when females are more promiscuous, males have to work harder -- at the genetic level, that is. More specifically, they determined that a protein controlling semen viscosity evolves more rapidly in primate species with promiscuous females than in monogamous species. The finding demonstrates that sexual competition among males is evident at the molecular level, as well as at behavioral and physiological levels.



The researchers, led by Howard Hughes Medical Institute investigator Bruce Lahn at the University of Chicago, published their findings in the November 7, 2004, issue of Nature Genetics. Lahn’s group studied semenogelin, a major protein in the seminal fluid that controls the viscosity of semen immediately following ejaculation. In some species of primates, it allows semen to remain quite liquid after ejaculation, but in others, semenogelin molecules chemically crosslink with one another, increasing the viscosity of semen. In some extreme cases, semenogelin’s effects on viscosity are so strong that the semen becomes a solid plug in the vagina. According to Lahn, such plugs might serve as a sort of molecular "chastity belt" to prevent fertilization by the sperm of subsequent suitors, though they might also prevent semen backflow to increase the likelihood of fertilization.

Lahn and his colleagues compared the SEMG2 gene, which contains the blueprint for semenogelin, from a variety of primates. They began by sequencing the SEMG2 gene in humans, chimpanzees, pygmy chimpanzees, gorillas, orangutans, gibbons, macaques, colobus monkeys, and spider monkeys. These species were chosen because they represent all the major mating systems, including those in which one female copulates with one male in a fertile period (such as gorillas and gibbons); those in which females copulate highly promiscuously (such as chimpanzees and macaques); and those in which mating practices fall somewhere in between (such as orangutans where a female will copulate with the dominant male, but may also copulate with other males opportunistically).


"When we plotted data on the evolution rate of the semenogelin protein against the level of female promiscuity, we saw a clear correlation whereby species with more promiscuous females showed much higher rates of protein evolution than species with more monogamous females," said Lahn. The researchers measured protein evolution rates by counting the number of amino acid changes in the protein, then scaling it to the amount of evolutionary time taken to make those changes. "The idea is that in species with promiscuous females, there’s more selective pressure for the male to make his semen more competitive. It’s similar to the pressures of a competitive marketplace. In such a marketplace, competitors have to constantly change their products to make them better, to give them an edge over their rivals -- whereas, in a monopoly, there’s no incentive to change."

The finding constitutes the first specific evidence that different levels of sexual competition produce different genetic effects, said Lahn. It had been established previously that levels of polyandry -- the mating of one female with more than one male -- affected physiological traits. For example, more polyandrous species have larger testes capable of producing more sperm. There is a metabolic cost to such adaptation, Lahn said, and in species where there is no competition, the cost is not worth the effort. "Now, for the first time, we show such competitive effects, not only at the level of physiology, but of individual genes," said Lahn. "The genes have to adapt faster for any given male to gain an edge over his competitors."

According to Lahn, while other studies have indicated that male reproductive genes in general tend to evolve more rapidly than other genes, "this study extends those observations to a more quantitative level, showing that the rate of evolution actually correlates with how intense the sexual selection is."

Jennifer Michalowski | EurekAlert!
Further information:
http://www.hhmi.org

More articles from Life Sciences:

nachricht Research team creates new possibilities for medicine and materials sciences
22.01.2018 | Humboldt-Universität zu Berlin

nachricht Saarland University bioinformaticians compute gene sequences inherited from each parent
22.01.2018 | Universität des Saarlandes

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>