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    Sex Reversal: In Brazilian Cave Insects, Females Have The Penises
    By News Staff | April 17th 2014 09:40 AM | 1 comment | Print | E-mail | Track Comments

    Researchers have discovered little-known cave insects, four distinct but related species in the genus Neotrogla, with rather novel sex lives - the first example of an animal with sex-reversed genitalia.


    Not sex roles, like the alphabet of letters we get in western culture, actual sex organ reversal.

    That's not the only fascinating aspect.Copulation lasts an impressive 40 to 70 hours and the female insects insert an elaborate, penis-like organ into males' much-reduced, vagina-like opening.

    The researchers speculate that the insects' sex organs and sex-role reversal may have been driven over evolutionary time by the resource-poor cave environment in which the bugs live. Males of the genus provide females with nutritious seminal gifts in addition to sperm, making it advantageous for females to mate at a higher rate.


    The terminal abdomens in copula, lateral. Credit: Current Biology, Yoshizawa et al.

    "Although sex-role reversal has been identified in several different animals, Neotrogla is the only example in which the intromittent organ is also reversed," says Kazunori Yoshizawa from Hokkaido University in Japan.

    At first, Rodrigo Ferreira from the Federal University of Lavras in Brazil was focused on a description of species in the cave environment where Neotrogla lives. He sent specimens off to insect specialist Charles Lienhard in Geneva, who recognized them as a new genus. Lienhard also discovered the females' very impressive penis-like organs.

    Yoshizawa joined the team to take a closer look. To learn more, the researchers observed the mating behavior of all four species to find that the penis-like structure, termed the gynosome, is inserted into males and used to receive generous capsules of nourishment and sperm. Once inside a male, the membranous part of the female gynosome inflates and numerous spines internally anchor the two insects together.

    In one instance, when the researchers attempted to pull a male and female apart, the male's abdomen was ripped from the thorax without breaking the genital coupling. In other words, it appears that females can hold males very tightly indeed.



    The female penis of N. aurora.That kind of "Crying Game" ending doesn't just happen in movies. Say hello to her little friend. Credit:  Current Biology, Yoshizawa et al.

    The findings pave the way for interesting studies in these insects to learn what makes them so special. Neotrogla offers new opportunities to test ideas about sexual selection, conflict between the sexes, and the evolution of novelty, the researchers say.

    "It will be important to unveil why, among many sex-role-reversed animals, only Neotrogla evolved the elaborated female penis," says Yoshitaka Kamimura from Keio University in Japan. For that, the researchers will look into studies of behavior, physiology, and more. First on the list, they say, is to establish a healthy population of the insects in the lab.


    Citation:  Kazunori Yoshizawa , Rodrigo L. Ferreira, Yoshitaka Kamimura, Charles Lienhard, 'Female Penis, Male Vagina, and Their Correlated Evolution in a Cave Insect', Current Biology April 17 2014 DOI:10.1016/j.cub.2014.03.022

    Comments

    Hank
    Jason Goldman covers the 'is it a gynosome or a female penis?' debate which has threatened to tear apart familes and erupt into open war...okay, it hasn't. Aside from pedants who argue about accuracy in order to sound smart and comprehensive, no one worries the public is getting the wrong idea about biology if it's called a female penis. The researchers used it in their title, the editors and peer reviewers cleared it.

    But Jason discusses what it means, which is a much more interesting thing.