Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 


Hidden costs of sex

Media Release
March 31, 2005

Hidden costs of sex

An evolutionary biologist at The University of Auckland has answered one of biology’s most puzzling questions, “Why did sex evolve and persist?”

Dr Matthew Goddard at the School of Biological Sciences, within the Faculty of Science, says the question has been a problem for evolutionary biology because, unlike asexual reproduction, sex requires the expenditure of time and energy.

In addition, he says, sexual reproduction disrupts favourable gene combinations and has a “two-fold cost”. This is because in organisms with unequal-sized gametes or reproductive cells, the female transmits genes at only half the rate of an asexual equivalent.

“On the face of it, this means it is much easier for organisms to reproduce themselves asexually,” he said.

Dr Goddard, who recently joined the University from Imperial College, London, set out to uncover the hard evidence to test a 100-year-old hypothesis – the Weismann effect - that sex allows more effective natural selection because it increases genetic variation.

In a paper, published today in “Nature”, Dr Goddard says his research on yeast populations, which can reproduce both asexually and sexually, has shown that sex does in fact increase the rate of a species’ adaptation to a harsh environment, but has no measurable effect on fitness in a benign environment.

Dr Goddard says when yeast cells are supplied with sufficient nutrients they reproduce asexually, but deprivation of nutrients triggers sexual reproduction.

But it has been difficult to study the net effect of sex on the organism’s rate of adaptation, he says, because the yeast cells have been subject to different environmental conditions.

Advances in knowledge about the molecular mechanisms of cell division in yeasts enabled Dr Goddard to develop a new asexual strain of yeast, which continues to reproduce asexually even when deprived of nutrients.

In turn, this enabled Dr Goddard to directly compare the rate of adaptation of the new asexual yeast population with a wild yeast population placed under the same environmental conditions.

Dr Goddard says his results indicate that sexual reproduction provides a selective advantage for adaptation to new environments and support Weismann’s ideas.

“They are an advance on earlier studies because by manipulating the sexual status of the yeast, we have mimicked the natural situation more closely and excluded a variety of possible confounding factors.”

Population experiments with fast-replicating micro-organisms have been very valuable in testing different ideas about the maintenance of sex, he said.

“A challenge now is to understand the nature of the mutations that underlie adaptation and to extend these techniques to larger plants and animals.”

- Ends -

© Scoop Media

 
 
 
 
 
Business Headlines | Sci-Tech Headlines

 

Half A Billion Accounts: Yahoo Confirms Huge Data Breach

The account information may have included names, email addresses, telephone numbers, dates of birth, hashed passwords (the vast majority with bcrypt) and, in some cases, encrypted or unencrypted security questions and answers. More>>

Rural Branches: Westpac To Close 19 Branches, ANZ Looks At 7

Westpac confirms it will close nineteen branches across the country; ANZ closes its Ngaruawahia branch and is consulting on plans to close six more branches; The bank workers union says many of its members are nervous about their futures and asking ... More>>

Interest Rates: RBNZ's Wheeler Keeps OCR At 2%

Reserve Bank governor Graeme Wheeler kept the official cash rate at 2 percent and said more easing will be needed to get inflation back within the target band. More>>

ALSO:

Half Full: Fonterra Raises Forecast Payout As Global Supply Shrinks

Fonterra Cooperative Group, the dairy processor which will announce annual earnings tomorrow, hiked its forecast payout to farmers by 50 cents per kilogram of milk solids as global supply continues to decline, helping prop up dairy prices. More>>

ALSO:

Results:

Meat Trade: Silver Fern Farms Gets Green Light For Shanghai Maling Deal

The government has given the green light for China's Shanghai Maling Aquarius to acquire half of Silver Fern Farms, New Zealand's biggest meat company, with ministers satisfied it will deliver "substantial and identifiable benefit". More>>

ALSO:

Get More From Scoop

 
 
 
 
 
 
 
 
 
Sci-Tech
Search Scoop  
 
 
Powered by Vodafone
NZ independent news