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    Pregnant Male Pipefish Inflict Abortion for More Desirable Females

    A male pipefish with eggs attached at its brood pouch. In the case of male Pipefish, the proverbial algae seems to be greener with larger, thus more attractive females. Male members of the Syngnathidae family have long been seen as the perfect dad by raising and nurturing their offspring. This view may change thanks to […]

    A male pipefish with eggs attached at its brood pouch.

    In the case of male Pipefish, the proverbial algae seems to be greener with larger, thus more attractive females. Male members of the Syngnathidae family have long been seen as the perfect dad by raising and nurturing their offspring. This view may change thanks to a recent study published in Nature, by Kim Paczolt at Texas A&M University that shows self interest in males and sexual conflict with females may play a larger roll than ever imagined.  In the study it was found that male Gulf Pipefish (Syngathus scovelli) may abort its unborn offspring created with undesirable females by killing them, in hopes of securing better eggs with a larger more fecund female. Abortion by male pipefish is not as uncommon as one may think. It has been found that males can deliberately abandon the embryos and absorb their nutrients; however, this activity was previously linked with malnourishment in the male egg carrier.

    The team found that males aborted far fewer embryos, and retained more of them when mating with larger females. This post-copulatory sexual selection is an unexplored link in ‘brood pouch evolution’.  That is because the surviving rate of embryos was correlated with the size of the female parent. Scientists are still unsure why males are attracted to larger females, but it is believe to follow a broad correlation among fishes–larger female equates to larger, healthier eggs. On the matter Paczolt said, “the pipefish brood pouch is turning out to be more complicated than we thought.”

    For more info see the abstract below and check out this brief video clip by Nature.

    “Male pregnancy in seahorses, pipefishes and sea dragons (family Syngnathidae) represents a striking reproductive adaptation that has shaped the evolution of behaviour and morphology in this group of fishes1, 2, 3, 4. In many syngnathid species, males brood their offspring in a specialized pouch, which presumably evolved to facilitate male parental care5, 6. However, an unexplored possibility is that brood pouch evolution was partly shaped by parent–offspring or sexual conflict, processes that would result in trade-offs between current and future pregnancies. Here we report a controlled breeding experiment using the sexually dimorphic Gulf pipefish, Syngnathus scovelli, to test for post-copulatory sexual selection within broods and for trade-offs between successive male pregnancies as functions of female attractiveness. Offspring survivorship within a pregnancy was affected by the size of a male’s mate, the number of eggs transferred and the male’s sexual responsiveness. Significantly, we also found that embryo survivorship in a current pregnancy was negatively related to survivorship in the prior pregnancy, clearly demonstrating fitness trade-offs between broods. Overall, our data indicate that post-copulatory sexual selection and sexual conflict occur in Gulf pipefishes. The conflict seems to be mediated by a strategy of cryptic choice in which males increase rates of offspring abortion in pregnancies from unattractive mothers to retain resources for future reproductive opportunities. Hence, the male brood pouch of syngnathid fishes, which nurtures offspring7, 8, 9, also seems to have an important role as an arbiter of conflict between the sexes.

    Department of Biology, 3258 TAMU, Texas A&M University, College Station, Texas 77845, USA

    [nat geo, nature]

    2 Comments

    1. Frode
      March 20, 2010 at 8:36 PM | Permalink

      Love this kind of info. Great explanatory video. Want to use it in my biology class.

    2. Frode
      March 20, 2010 at 3:36 PM | Permalink

      Love this kind of info. Great explanatory video. Want to use it in my biology class.

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