 |
|
Study finds role for parasites in evolution of sex
July 07, 2009What'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 sex-like microbes, some plants and even a few reptiles-would 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 clones-exact 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 parasites-in spite of their nasty reputation-for the joy of sex.
University of Chicago Press Journals
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 parasites-in spite of their nasty reputation-for the joy of sex.
University of Chicago Press Journals
Parasite Current Events and Parasite News RSSMeasuring and modeling blood flow in malaria
When people have malaria, they are infected with Plasmodium parasites, which enter the body from the saliva of a mosquito, infect cells in the liver, and then spread to red blood cells.
Small nanoparticles bring big improvement to medical imaging
If you're watching the complex processes in a living cell, it is easy to miss something important-especially if you are watching changes that take a long time to unfold and require high-spatial-resolution imaging.
Anisakiasis hazard varies depending on the origin of the fish, according to a study
A research team of the University of Granada (Spain) has confirmed a higher presence of the parasite Anisakis spp in anchovies of the Atlantic South East coast and the Mediterranean North West coast, and they insist on freezing or cooking fish before consuming it.
DNA barcodes: Creative new uses span health, fraud, smuggling, history, more
The scientific ability to quickly and accurately identify species through DNA "barcoding" is being embraced and applied by a growing legion of global authorities - from medical and agricultural researchers to police and customs authorities to palaeontologists and others.
PATH Malaria Vaccine Initiative shares strategy for developing 'next-generation' malaria vaccines
Marking its tenth anniversary year, the PATH Malaria Vaccine Initiative (MVI) today unveiled a new strategy that sets the stage for an aggressive push targeting the long-term goal of eliminating and eradicating malaria. Malaria is one of the world's deadliest infectious diseases, killing nearly 900,000 people a year, most of them children in sub-Saharan Africa.
Pitt, US Army team designs new strategy to find drugs to treat neglected infection
Using an unconventional approach that they designed, University of Pittsburgh drug discoverers and their collaborators at Walter Reed Army Institute of Research have identified compounds that hold promise for treating leishmaniasis, a parasitic infection that many consider one of the world's most overlooked diseases.
Media availability: The role of biomedical research in malaria eradication
Although malaria has been controlled in many local and regional populations, the permanent elimination of malaria parasites throughout the world remains an elusive goal, and the disease continues to claim nearly one million lives each year.
New insight in the fight against the Leishmania parasite
Professor Albert Descoteaux's team at Centre INRS - Institut Armand-Frappier has gained a better understanding of how the Leishmania donovani parasite manages to outsmart the human immune system and proliferate with impunity, causing visceral leishmaniasis, a chronic infection that is potentially fatal if left untreated.
Male Australian redback spiders employ courtship strategies to preserve their life
New research shows that male suitors of a female cannibalistic spider risk facing a premature death unless they perform an adequate courtship lasting a minimum of 100 minutes. Further, the research shows that "sneaker" males can slip by and mate successfully on the courtship efforts of the hard-working first suitor.
Better blood screening process needed to prevent babesiosis transmission
Babesiosis is a potentially dangerous parasitic disease transmitted by ticks and is common in the Northeast and the upper Midwest. Babesia lives inside of red blood cells, meaning it can also be transmitted through a blood transfusion from an infected but otherwise asymptomatic blood donor.
More Parasite Current Events and Parasite News Articles
 |
Parasite Rex : Inside the Bizarre World of Nature's Most Dangerous Creatures by Carl Zimmer (Author) IMAGINE A WORLD WHERE parasites control the minds of their hosts, sending them to their destruction. IMAGINE A WORLD WHERE parasites are masters of chemical warfare and camouflage, able to cloak themselves with their hosts' own molecules. IMAGINE A WORLD WHERE parasites steer the course of evolution, where the majority of species are parasites. WELCOME TO EARTH. For centuries, parasites have lived in nightmares, horror stories, and in the darkest shadows of science. Yet these creatures are among the world's most successful and sophisticated organisms. In Parasite Rex, Carl Zimmer deftly balances the scientific and the disgusting as he takes readers on a fantastic voyage. Traveling from the steamy jungles of Costa Rica to the fetid parasite haven of southern Sudan,... |
 |
The Parasite (Posthumanities) by Michel Serres (Author) Influential philosopher Michel Serres’s foundational work uses fable to explore how human relations are identical to that of the parasite to the host body. Among Serres’s arguments is that by being pests, minor groups can become major players in public dialogue—creating diversity and complexity vital to human life and thought.
Michel Serres is professor in history of science at the Sorbonne, professor of Romance languages at Stanford University, and author of several books, including Genesis.
Lawrence R. Schehr is professor of French at the University of Illinois, Urbana-Champaign. |
 |
Guess What Came to Dinner?: Parasites and Your Health by Ph.D., CNS, Ann Louise Gittleman (Author) With more than 60,000 copies sold, a newly revised and updated edition of an authoritative book on parasitic infections-their detection, treatment, and cure. Once relegated to poor third-world countries, instances of parasitic infections are on a dramatic rise in the United States. In this thoroughly revised and updated edition of Guess What Came to Dinner?, health expert Ann Louise Gittleman informs readers about the role of parasites in many ailments, from allergies to chronic fatigue syndrome and bowel disorders. The book offers practical advice to parasite-proof your food and water and explains breakthrough methods of detection, anti-parasitic treatments, and herbal cures. Notes. Index. |
 |
Dr. Natura Colonix -Colon Cleanse complete Kit - (Liver, Kidney, Colon, And Parasite Cleanse) by Dr. Natura The Colonix Intestinal Cleanser is a fiber supplement that cleanses the colon of accumulated toxic build-up and prevents the formation of new build-up through the use of herbal dietary fiber. Continued use of the Colonix Intestinal Cleanser keeps the digestive tract from getting clogged up with mucus, toxins and metabolic waste. It helps to keep the colon clean and waste matter moving freely and efficiently. Fiber also helps maintain a healthy intestinal flora and absorbs toxins in the colon by creating a spongy, gelatinous mass in the bowels. By swelling and absorbing fluids, it breaks down and moves toxic waste matter stuck in the folds and crevices of the colon. A clean colon inhibits harmful bacteria and parasites from surviving on human waste. Paranil Anti-Parasite Support helps to... |
 |
Parasite Starring: Robert Glaudini, Demi Moore, Luca Bercovici, James Davidson (II), Al Fann Directed By: Charles Band |
 |
Retro Pop Remasters: Best of Parasites by Parasites |
 |
The Art of Being a Parasite by Claude Combes (Author), Daniel Simberloff (Translator) Parasites are a masterful work of evolutionary art. The tiny mite Histiostoma laboratorium, a parasite of Drosophila, launches itself, in an incredible display of evolutionary engineering, like a surface-to-air missile at a fruit fly far above its head. Gravid mussels such as Lampsilis ventricosa undulate excitedly as they release their parasitic larval offspring, conning greedy predators in search of a tasty meal into hosting the parasite. The Art of Being a Parasite is an extensive collection of these and other wonderful and weird stories that illuminate the ecology and evolution of interactions between species. Claude Combes illustrates what it means to be a parasite by considering every stage of its interactions, from invading to reproducing and leaving the host. An accessible... |
 |
The Parasite Menace by Skye Weintraub (Author) |
 |
Every Body Has Parasites by Valerie Saxion (Author) Do you have a chronic health problem that you just can shake off? Perhaps you have intestinal problems that come and go? Or you¹re tired all the time and feel depressed? Have you consulted with a physician but not found an answer? It is very possible that the cause of what you are experiencing is directly due to parasites. Don¹t cling to the notion that parasites are limited to the Third World. Parasitic experts estimate that there are between 100 and 130 common parasites being hosted in the American populace today, and a recent health report stated that 85 percent of Americans are infected with parasites. The trick is that the symptoms caused by parasites are subtle because they are experienced commonly by people without parasites, and the vast majority of health-care... |
 |
Eco Clear - Body Ecology's Parasite Cleanse by Body Ecology Diet Anti-Parasite Formula. Intestinal Cleansing Dietary Supplement EcoClear uses a unique, full spectrum, combination of pure, traditional botanicals to eliminate all types of parasites. EcoClear is a proprietary blend of Holerrhena antidysentrica bark, Black Seed, Coriander seed, Basil leaf, Neem leaf, Embelia ribes herb, Black Walnut hull, Clove, Wormwood extract, Peppermint leaf, and Grapefruit seed extract. 120 capsules |
| © 2009 BrightSurf.com |