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Sperm trading can resolve hermaphrodite mating conflicts
October 11, 2005By directly manipulating mating performance in a tropical sea slug, Chelidonura hirundinina, researchers of the University of Tübingen have now shed light on the bizarre reproductive conflicts encountered by hermaphroditic animals. In some hermaphroditic species, such as C. hirundinina, mating partners may insist on copulating as a "male," "female," or both, resulting in unique biological conflicts over gender.
Sexual interactions in so-called cross-fertilizing simultaneous hermaphrodites, such as earthworms, snails, leeches, and some fishes, have long challenged researchers' understanding of how established theories regarding sexual selection apply in cases of hermaphroditic species. For example, combining male and female gender in one and the same individual, hermaphrodites have been predicted to frequently be at conflict (theoretically speaking) about which sexual roles to play, because matings are often more costly, in terms of evolutionary fitness, to one gender than to the other. In such cases, hermaphrodites are predicted to share a preference to copulate in the more beneficial gender role. This would appear to make the interests of any two potential mates incompatible. For 20 years, evolutionary biologists have speculated that hermaphrodites may solve such mating conflicts by "trading sperm," that is, giving sperm only when the mating partner follows suit. However, this prediction had never been proven experimentally.
In the new work, researchers Nils Anthes, Annika Putz, and Nico Michiels generated individual sea slug hermaphrodites only capable of performing a "dry" copulation-that is, without sperm transfer. Sea slugs that mated with such a "cheating" partner interrupted sexual intercourse significantly sooner than did control pairs. This supports the concept of sperm trading, where mates negotiate mating roles in order to balance sexual interactions.
Cell Press
Cell Press
Hermaphrodite Current Events and Hermaphrodite News RSSWhy don't more animals change their sex?
Most animals, like humans, have separate sexes - they are born, live out their lives and reproduce as one sex or the other. However, some animals live as one sex in part of their lifetime and then switch to the other sex, a phenomenon called sequential hermaphroditism.
First experimental evidence for speedy adaptation to pesticides by worm species
Scientists at the Instituto Gulbenkian de Ciencia (IGC) and the Faculty of Science of the University of Lisbon, in Portugal, have shown that populations of the worm Caenhorabditis elegans become resistance to pesticides in 20 generations, that is, in only 80 days.
Mate or hibernate? That's the question worm pheromones answer
If worms could talk, they might tell potential suitors, "I like the way you wriggle," complete with that telltale come slither look.
Living laboratory found on shoreline statues
A team from the University of Liverpool's School of Biological Sciences have found that the 100 life-size statues which make up Antony Gormley's 'Another Place' art installation on Crosby Beach have become a haven for a settlement of a particular breed of barnacle-Elminius modestus.
Hermaphroditic plants have genetic advantage in areas where extinctions are frequent
In one of the first studies to empirically compare the reproductive success of hermaphrodites and male and female populations, biologists from the University of Oxford make use of the rare and extreme sexual diversity displayed in a species of European weed to test the hypothesis that hermaphrodites have been selected in regions with frequent extinction and re-colonization.
Pollutant threat to oyster industry
A study published today reveals that a common industrial chemical causes sexual deformities in oysters, producing large numbers of hermaphrodite animals. The chemical, nonylphenol, is a breakdown product from a surfactant widely used in detergents, dispersing agents, herbicides, spermicides and cosmetics. Dr Helen Nice who undertook this study at Royal Holloway, University of London, says, 'Our results may cast doubt on the widespread use of this chemical in many human products including contraceptive spermicides.' Nonylphenol is a known endocrine disrupter - chemicals that interfere with the hormones of animals. It is discharged through sewage effluent and is therefore widespread in the aq
Science Of Strawberries
Goran Ivanisevic's offer to serve strawberries at this year's Wimbledon may be a more useful job than he imagined. As well as delicious with cream, this symbol of the summer could help fight cancer according to scientists. Research has shown that natural plant chemicals in strawberries can inhibit the growth of cancer cells. And now scientists at the Institute of Food Research have begun work to identify the compounds responsible. "The modern strawberry is just one of hundreds of varieties cultivated worldwide. There are also about twenty wild species. They all have different properties - visible in the size, shape and colour of the fruit, or the size and abundance of flowers. The aim of
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The Hermaphrodite (Legacies of Nineteenth-Century American Women Writers) by Julia Ward Howe (Author), Gary Williams (Editor), Gary Williams (Editor) Written in the 1840s and published here for the first time, Julia Ward Howe’s novel about a hermaphrodite is unlike anything of its time—or, in truth, of our own. Narrated by Laurence, who is raised and lives as a man and is loved by men and women alike, yet can respond to neither, this unconventional story explores the realization “that fervent hearts must borrow the disguise of art, if they would win the right to express, in any outward form, the internal fire that consumes them.” Laurence describes his repudiation by his family, his involvement with an attractive widow, his subsequent wanderings and eventual attachment to a sixteen-year-old boy, his own tutelage by a Roman nobleman and his sisters, and his ultimate reunion with his early love. His is a story unique in... |
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XXy Starring: Ricardo DarÃÂÂn, German Palacios, Jean Pierre Reguerraz, Ines Efron, Martin Piroyanski Directed By: Lucia Puenzo Studio: Repnet Llc Release Date: 10/14/2008 |
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Hermaphrodite by Eric Copeland |
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Intersex (For Lack of a Better Word) by Thea Hillman (Author) “In Hillman’s world, the surer you become about who you are, the more vulnerable you get.”—The San Francisco Bay Guardian “Hillman’s writing is sexy because it’s smart and refuses to simplify things.”—Fabula Magazine "Hillman's utterly unabashed memoir...showcases both the personal, embodied realities of intersex, and the social and political milieus that shape them... Intersex, too, is gorgeously written."—Women's Review of Books "It's utterly impossible to not be spellbound by performer-activist Thea Hillman, in person or in print ... A must-read."—Curve “There’s nothing else in print like this amazing and courageous book.”—Patrick Califia, author of Sex Changes: The Politics of Transgenderism “An important... |
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Hermaphrodites and the Medical Invention of Sex by Alice Domurat Dreger (Author) Punctuated with remarkable case studies, this book explores extraordinary encounters between hermaphrodites -- people born with "ambiguous" sexual anatomy -- and the medical and scientific professionals who were confronted by them. |
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That Pistol-Packin' Hermaphrodite Also With: Warner Bros. (Producer) |
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Starrett 51143 243-6 6"hermaphrodite Starrett Firm Jt Caliper by Starrett Dividers Springs - Calipers Type: Firm Joint Hermaphrodite Caliper Maximum Measuring: 6 Finish/Coating: Polished Material: Ground Steel | |
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Herculine Barbin (Being the Recently Discovered Memoirs of a Nineteenth Century French Hermaphrodite) by Michel Foucault (Author), Richard McDougall (Translator) With an eye for the sensual bloom of young schoolgirls, and the torrid style of the romantic novels of her day, Herculine Barbin tells the story of her life as a hermaphrodite. Herculine was designated female at birth. A pious girl in a Catholic orphanage, a bewildered adolescent enchanted by the ripening bodies of her classmates, a passionate lover of another schoolmistress, she is suddenly reclassified as a man. Alone and desolate, he commits suicide at the age of thirty in a miserable attic in Paris. Here, in an erotic diary, is one lost voice from our sexual past. Provocative, articulate, eerily prescient as she imagines her corpse under the probing instruments of scientists, Herculine brings a disturbing perspective to our own notions of sexuality. Michel Foucault, who discovered... |
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