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News: ScienceShot: Survival of the Fittest, Inside a Shark's Womb

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  • Robert Karl Stonjek
    ScienceShot: Survival of the Fittest, Inside a Shark s Womb by Paul Gabrielsen on 30 April 2013, 7:45 PM Credit: Debra Abercrombie And you thought human
    Message 1 of 2 , May 3, 2013
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      ScienceShot: Survival of the Fittest, Inside a Shark's Womb

      by Paul Gabrielsen on 30 April 2013, 7:45 PM
       
      sn-sandshark.jpgCredit: Debra Abercrombie

      And you thought human sibling rivalry was intense. Sand tiger sharks (Carcharias taurus) eat all of their brothers and sisters —before anyone has even been born. A new study shows that the shark pups' "embryonic cannibalism" serves a Darwinian purpose, ensuring survival of the fittest. Researchers studied 15 pregnant sand sharks carrying up to nine eggs in twin uteri. The eggs sported enough genetic diversity to indicate that the litter had multiple fathers. But not all of those dads got to pass on their dashing good looks to Junior. When sand shark eggs hatch, the first hatchling in each uterus (shown, at right, with embryo at left) eats all the rest, leaving only two pups per litter. In about 60% of the sharks studied, the two surviving hatchlings had the same fit father, the team reports in the latest issue of Biology Letters. Embryonic cannibalism may favor faster growth rates or "the precocious development of eyes and teeth," the team writes, "which enhances their ability to locate and consume their siblings." Fighting over the top bunk seems trivial in comparison.

      Source: ScienceNow
      http://news.sciencemag.org/sciencenow/2013/04/scienceshot-survival-of-the-fitt.html?ref=em

      Posted by
      Robert Karl Stonjek

    • james kohl
      Excerpt: In about 60% of the sharks studied, the two surviving hatchlings had the same fit father... The odds are decidedly against this unless the
      Message 2 of 2 , May 4, 2013
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        Excerpt: "In about 60% of the sharks studied, the two surviving hatchlings had the same fit father..." The odds are decidedly against this unless the hatchlings identify their genetic similarity via olfaction and pheromones, which is consistent with my model.
         
        James V. Kohl
        Medical laboratory scientist (ASCP)
        Independent researcher
        Kohl, J.V. (2012) Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors. Socioaffective Neuroscience & Psychology, 2: 17338.



        From: Robert Karl Stonjek <stonjek@...>
        To: Evolutionary Psychology News <evol_psch_news@yahoogroups.com>; Evolutionary-Psychology <evolutionary-psychology@yahoogroups.com>
        Sent: Sat, May 4, 2013 2:12:52 AM
        Subject: [evol-psych] News: ScienceShot: Survival of the Fittest, Inside a Shark's Womb

         

        ScienceShot: Survival of the Fittest, Inside a Shark's Womb

        by Paul Gabrielsen on 30 April 2013, 7:45 PM
         
        sn-sandshark.jpgCredit: Debra Abercrombie

        And you thought human sibling rivalry was intense. Sand tiger sharks (Carcharias taurus) eat all of their brothers and sisters —before anyone has even been born. A new study shows that the shark pups' "embryonic cannibalism" serves a Darwinian purpose, ensuring survival of the fittest. Researchers studied 15 pregnant sand sharks carrying up to nine eggs in twin uteri. The eggs sported enough genetic diversity to indicate that the litter had multiple fathers. But not all of those dads got to pass on their dashing good looks to Junior. When sand shark eggs hatch, the first hatchling in each uterus (shown, at right, with embryo at left) eats all the rest, leaving only two pups per litter. In about 60% of the sharks studied, the two surviving hatchlings had the same fit father, the team reports in the latest issue of Biology Letters. Embryonic cannibalism may favor faster growth rates or "the precocious development of eyes and teeth," the team writes, "which enhances their ability to locate and consume their siblings." Fighting over the top bunk seems trivial in comparison.

        Source: ScienceNow
        http://news.sciencemag.org/sciencenow/2013/04/scienceshot-survival-of-the-fitt.html?ref=em

        Posted by
        Robert Karl Stonjek

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