jueves, 22 de abril de 2010

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Male Spiders Have Safer Sex With Siblings

argiope_bruennichi
Inbreeding isn’t worth dying for, even in a spider species where males routinely pay for sex with their lives.
sciencenewsSex is never safe for males of the species Argiope bruennichi, one of Europe’s common orb-web spiders. In lab tests conducted by behavioral ecologists at the Zoological Institute and Museum of the University of Hamburg, males ended up as their mates’ lunch in about three trysts out of four.
But when researchers matched up siblings the cannibalism rate fell to about half, mostly because the males beat a hasty retreat, Klaas Welke and Hamburg colleague Jutta Schneider report online the week of April 19 in Biology Letters.
Males who found themselves paired with their sisters suspended relations after an average of six seconds, fast enough to improve their odds of escaping the female afterward. With an unrelated female, the average was about nine seconds.
The study suggests that males balance their chance of reproductive success against their risk of being eaten by adjusting how much time they spend mating.

Biologists have long recognized that mating with close relatives can lead to trouble, such as fewer or weaker offspring down the line. In species where females make greater investments in young or mate fewer times, biologists have predicted that females would be especially fussy about the risk of inbreeding.
But in Argiope bruennichi, males have more restrictions on mating. Each male has two sperm-delivery organs, or pedipalps, and they’re not reusable. During mating a bit breaks off, usually the tip, and acts as a partial plug in the female reproductive tract that makes insertion difficult for later males. Despite this barrier, females can still mate again, but males get only two shots.
“The males should be choosy,” Welke says.
And that’s how the experiment turned out. The researchers knew the family origin of each spider because they reared the arachnids from egg sacs collected in the wild. When the spiders grew up, researchers paired 45 females with sibling males and 46 with nonsiblings, and then compared reactions.
Just how males recognize their kin isn’t clear yet. But Welke notes that if spiderlings have the brain capacity to learn their siblings, they have months to do so. Mom lays the egg sac in summer, but youngsters hatch inside and stay cooped up until the next spring.
This finding of inbreeding avoidance in males intrigues Trine Bilde of Aarhus University in Denmark, who has studied the female side of inbreeding in spiders. It’s another twist in the tale of cannibals, which have proved quite informative to biologists. “It is interesting to study sexually cannibalistic species to understand how evolution can possibly favor self-sacrificing males,” she says.
Image: Female Argiope bruennichi./Coussier/flickr.

Read More http://www.wired.com/wiredscience/2010/04/spider-incest/#ixzz0lrFsGyTe

1 comentario:

  1. ¿Y en qué garage se desarrolló la simby o diversidad?

    Pues en la sensosfera, también un poco de enosfera, bañosdelcarmensfera, cradecadizfera, rinconvictoiresfera, y campustetatinossfera, universibares, auniversioplayas, cerros montesferas, cochesferas (por cierto no hay sonido más maravilloso que el de un coche yéndose, alejando se en la distancia....es una sensacion nada envidiable a la mejor musica, incluso la celestial, claro, si es de noche, mejor... y una esferillla muy chikititilla, chikititilla, chikititilla... (a ojos claro de quien ni la roza) que le llaman internés...
    hablando de garage y de novedades que ponemos a su disposicion en esta primavera verano está el servidor mocoputomoco, el sistema operativo minouX, el sistema matematico infimoniko, la web líquida o OUED, el descodificador instantaneo copylife, la instant university, la instant democracy, dequeing, o indice de calidad democratica, un comarcalización biogeografica bipolar y bio o simbio politica: AFROROPA + rizomecs, INDICE DE inclusividad linguistica, simbiodomotica, gaya symplectic index, PERO CON UNA SALVEDAD, segun queda recogido en el copylife, estos palabros son semillas que germinan desde la biología del amor en aquellos ambitos donde puedan o quieran ser utilizados, por ej, en una clase formal.
    Soponen un empoderamiento progresivo del ser humano que hay en tu propio y simbiótico cuerpo, a traves de las teorias más actuales y más desconocidas de la ciencia, da igual en que carrera o tema preferido tengas. Porque al ser teorias y practicas integradoras casan todas con todas. Casan todas con todas cuando has adquirido practica neurosemantica con ellas, desde la posibilidad de regalarte un regalo que empieza por creer que no hay nada que creer sino de crear.
    Sin miramientos pues
    acerquese usted a estos enturtos,
    que nunca saldra malparao,
    si acaso algunas creencias de más se
    iran evaporando,
    mas fluido usted volara
    y de nada le diremos al marchar

    ResponderEliminar

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