Navigation Links
Study finds role for parasites in evolution of sex
Date:7/6/2009

What's so great about sex? From an evolutionary perspective, the answer is not as obvious as one might think. An article published in the July issue of the American Naturalist suggests that sex may have evolved in part as a defense against parasites.

Despite its central role in biology, sex is a bit of an evolutionary mystery. Reproducing without sexlike microbes, some plants and even a few reptileswould seem like a better way to go. Every individual in an asexual species has the ability to reproduce on its own. But in sexual species, two individuals have to combine in order to reproduce one offspring. That gives each generation of asexuals twice the reproductive capacity of sexuals. Why then is sex the dominant strategy when the do-it-yourself approach is so much more efficient?

One hypothesis is that parasites keep asexual organisms from getting too plentiful. When an asexual creature reproduces, it makes clonesexact genetic copies of itself. Since each clone has the same genes, each has the same genetic vulnerabilities to parasites. If a parasite emerges that can exploit those vulnerabilities, it can wipe out the whole population. On the other hand, sexual offspring are genetically unique, often with different parasite vulnerabilities. So a parasite that can destroy some can't necessarily destroy all. That, in theory, should help sexual populations maintain stability, while asexual populations face extinction at the hands of parasites.

The scenario works on mathematical models, but there have been few attempts to see if it holds in nature.

Enter Potamopyrgus antipodarum, a snail common in fresh water lakes in New Zealand. What makes these snails interesting is that there are sexual and asexual versions. They provide scientists with an opportunity to compare the two versions side-by-side in nature.

Jukka Jokela of the Swiss Federal Institute of Aquatic Science and Technology, Mark Dybdahl of the University of Washington and Curtis Lively of Indian University, Bloomington began observing several populations of these snails for ten years starting in 1994. They monitored the number of sexuals, the number asexuals, and the rates of parasite infection for both.

The team found that clones that were plentiful at the beginning of the study became more susceptible to parasites over time. As parasite infections increased, the once plentiful clones dwindled dramatically in number. Some clonal types disappeared entirely. Meanwhile, sexual snail populations remained much more stable over time. This, the authors say, is exactly the pattern predicted by the parasite hypothesis.

"The rise and fall of these female-only lineages was surprisingly fast and consistent with the prediction of the parasite hypothesis for sex," Jokela said. "These results suggest that sexual reproduction provides an evolutionary advantage in parasite rich environments."

So we may well have to thank parasitesin spite of their nasty reputationfor the joy of sex.


'/>"/>

Contact: Kevin Stacey
kstacey@press.uchicago.edu
773-834-0386
University of Chicago Press Journals
Source:Eurekalert

Related biology news :

1. Canadian researchers set to study impact of nanomaterials on aquatic ecosystems
2. MS study offers theory for why repair of brains wiring fails
3. Oscar Pistorius: Previously confidential study results released on amputee sprinter
4. NSF provides $3.4 million to study climatically important Agulhas Current
5. Plant protein doorkeepers block invading microbes, study finds
6. ESHRE launches international study of polar body screening
7. Environmental cues control reproductive timing and longevity, University of Minnesota study shows
8. Study finds DNA barcoding requires caution without closer examination
9. Study characterizes eczema patients most at risk for dangerous viral infections
10. UT San Antonio researcher wins $917,000 from NIH to study memory
11. Gene predicts how brain responds to fatigue, human study shows
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/20/2016)... JOSE, Calif. , Jan. 20, 2016 /PRNewswire/ ... developer of human interface solutions, today announced sampling ... controller solution for wearables and small screen applications ... such as printers. Supporting round and rectangular shapes, ... S1423 offers excellent performance with moisture on screen, ...
(Date:1/13/2016)... January 13, 2016 ... addition of the  "India Biometrics Authentication ... Forecast (2015-2020)"  report to their ... has announced the addition of the  ... - Estimation & Forecast (2015-2020)" ...
(Date:1/8/2016)... , January 8, 2016 ... market and WorldVentures ® , a privately held leading ... an Inc. 5000 fastest-growing company announced that ... investment of $2 million in Nxt-ID to develop a ... on Nxt-ID,s Wocket ® , a unique smart wallet ...
Breaking Biology News(10 mins):
(Date:2/9/2016)... Three-Year Initiative Supports Next Generation of ... in Life-Changing Camp Experiences ... affect the lives of children born with rare diseases, as well ... ) is announcing a new initiative designed to positively affect the ... future of rare disease care. --> To mark the ...
(Date:2/8/2016)... BIOREM Inc. (TSXV: BRM) ("Biorem" or "the Company") today announced ... companies in the TSX Venture 50 TM . ... TSX Venture Exchange, in each of five major industry sectors ... life sciences, diversified industries and technology – based on a ... market cap growth, trading volume and analyst coverage. All data ...
(Date:2/8/2016)... February 8, 2016 ... Limited, an innovation-driven oncology company developing next generation ... toxic, today announced that chairman emeritus of Tata ... in the company as part of the first ... existing investors Navam Capital and Aarin Capital. ...
(Date:2/8/2016)... 2016  BioElectronics Corporation (OTC Pink: BIEL), the ... that it is responding to a notice of ... and Exchange Commission posted on the agency website.  ... the Board of BioElectronics Corporation and the Edward ... The Fuqua School of Business, Duke University.   ...
Breaking Biology Technology: