Tiny Marsupials Have Such Frantic Sex It Kills Them

By Breanna Draxler | October 9, 2013 12:20 pm
Pulchera Waterhole, Mulligan River, Cravens Peak during Biodiversity research, Australia

This Australian phascogale can’t stick around for coffee or cuddling.  Image credit: Janelle Lugge/Shutterstock

Don’t be fooled by the prudish appearance of this mouse-sized marsupial—in an evolutionary strategy called suicidal reproduction, males literally sex themselves to death in order to pass on their genes.

Scientists have spent 30 years trying to figure out why this would be a good idea. Is it fewer mouths for the furry family to feed? Or eliminating unhelpful dads from the picture? Nope. New research says it comes down to promiscuous females and pumping out super sperm.

Marsupial Sperm Competition

Mating season for the dasyuridae marsupials of Australia, South American and Papua New Guinea is just a few weeks long. During this short window of fertility, the flirtatious females will take as much action as they can get. They aren’t picky, either, which means the males don’t need to fight each other for a share of the action. From outside the orgy, it appears that everyone wins. But inside the uterus, it’s survival of the fittest (sperm).

One of the researchers told NBC News,

“This is a form of post-mating sexual selection in which males compete with their sperm inside the female reproductive tract, rather than fighting to gain access to females.”

But that means that in order to pass on his genes, a male needs to make pretty magnificent sperm and fertilize as many females as possible. Since males don’t help raise the young, and they have a short lifespan to begin with, they give their one and only mating season all they’ve got.

Sexed to Exhaustion

These tiny guys copulate for up to 14 hours at a time, during which frenzied marsupial males’ levels of testosterone and stress hormones skyrocket. Even their muscles start to break down so that every ounce of energy they’ve got can be diverted to sex. 

Such all-out exertion kills many a male before season’s end. The focus on sperm- and baby-making causes other bodily functions to shut down, including their immune system. Males often die of internal bleeding or infections that their weakened bodies cannot fight off, before they’ve ever seen the fruits of their life-ending labor.

As New Scientist reports,

Rather than growing fighting-fit bodies, the males pour everything they have into fighting-fit sperm. This leaves them with nothing in reserve to fend off disease afterwards.

The study, published this week in Proceedings of the National Academy of Sciences, suggests that suicidal reproduction is an extreme example of sexual selection. In other words, don’t try this at home.

CATEGORIZED UNDER: Living World, top posts
  • No God Cast Podcast

    Death by coitus. That’s how I’d like to go.

  • jaimie bisbee

    My Uncle John just got an awesome silver Volkswagen CC by working
    online… hop over to these guys J­a­m­2­0­.­ℂ­o­m

  • Physics Police

    You could at least mention, in the article, the species name!

    Australian phascogale

    • Possum

      Looks to me like a planigale…
      “Australian phascogale” seems such a funny term… there’s no such species name, so ‘Australian’ must be an adjective here, but all phascogales are endemic to Australia.

    • Breanna Draxler

      I didn’t mention a specific species name in the article because the researchers looked at 52 different species of insectivorous marsupials in Australia, South American and Papua New Guinea over the course of their study. They compared species who don’t practice suicidal reproduction with those who do, including the antechinus, the phascogale and the dasykaluta.

      • Physics Police

        Oh, cool, thanks.

  • Guest

    Looks to me more like a planigale…
    “Australian phascogale” seems such a funny term… there’s no such species name, so ‘Australian’ must be an adjective here, but all phascogales are endemic to Australia.

    • Breanna Draxler

      Phascogale is the genus name, actually, and includes the species P. tapoatafa (brush-tailed phascogale) and P. calura (red-tailed phascogale). “Australian” was in reference to its geographic location, rather than its Latin nomenclature. I hope this clears things up!

  • tesmith47

    just one more timeeeeeeeeee

  • Michelle White-Julien

    Dude, just fake it!

  • Trey

    Come on ladies, i can’t take anymore

  • Rocketman

    Looks like a shrew to me! We have lots of those on and off in the southeast Texas area (at least at MY house!)

  • Tom Epstein

    This is how Captain Kirk should have died.

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