• Relatedness and size interact in shaping

    From ScienceDaily@1:317/3 to All on Monday, March 28, 2022 22:30:40
    Relatedness and size interact in shaping cannibal aggression

    Date:
    March 28, 2022
    Source:
    University of Jyva"skyla" - Jyva"skyla"n yliopisto
    Summary:
    New research finds that in addition to size difference, relatedness
    affects whether or not a poison frog tadpole is more likely to
    be eaten.



    FULL STORY ========================================================================== Cannibalism is common throughout the animal kingdom. It can be strange
    to think about real life "battle-royales" playing out in nature such
    that many individuals enter and only a few emerge victorious, but in
    the tropics we observe exactly that. According to researchers at the
    University of Jyva"skyla", Finland, in addition to size difference,
    relatedness affects whether or not a poison frog tadpole is more likely
    to be eaten.


    ========================================================================== Fathers of the dyeing poison frog, Dendrobates tinctorius, will transport
    their tadpoles to small pools of water where they are confined until metamorphosis.

    Tadpoles of this species are aggressive cannibals and resources in these
    small pools of water are limited. Thus, there is a fierce competition
    between individuals for resources to survive until metamorphosis. Although these nurseries become the arena for a battle-royale between tadpoles,
    there are instances where more than one individual survives to become
    a frog, indicating that sometimes cannibals let each other live. This
    led a research team based at the University of Jyva"skyla" to wonder:
    what exactly shapes aggressive decisions between individuals who
    have the ability to cannibalize each other? Researchers suspected
    that aggression could be mediated by relatedness, size differences,
    or perhaps a combination between these two forces. Biologically, there
    is precedence for siblings to be more tolerant of each other. This would
    mean that firstly, tadpoles have some mechanism of distinguishing related
    from unrelated individuals and secondly, that even if they do distinguish siblings they "care" enough about them to leave them alone. Alternatively, aggression could be determined by physical assessment, where size
    differences inform tadpoles about the competitive ability of the other. In theory, we would imagine that when size differences are large between competitors that overall aggression is lower, as the risks of a smaller
    fighter becoming a meal are high when faced with a much larger cannibal.

    Researchers were surprised to discover that cannibals care about the individuals they are faced to fight (up to a point). They found that
    large tadpoleswere half as aggressive towards their smaller siblings than towards non-siblings. In other words, cannibals are able to discriminate
    their siblings and change their behaviour accordingly.

    Thanks to this study, we now have more information to better understand
    the apparently strange decisions parents make when depositing their young children in pools that are already occupied by cannibals -- ultimately, high-quality nurseries are hard to find in the jungle, and parents may
    rather deposit their young in a superior pool with an older, larger
    sibling who they believe may forfeit an easy meal for the sake of family.


    ========================================================================== Story Source: Materials provided by University_of_Jyva"skyla"_-_Jyva"skyla"n_yliopisto. Note: Content may
    be edited for style and length.


    ========================================================================== Journal Reference:
    1. Chloe A Fouilloux, Lutz Fromhage, Janne K Valkonen, Bibiana
    Rojas. Size-
    dependent aggression towards kin in a cannibalistic
    species. Behavioral Ecology, 2022; DOI: 10.1093/beheco/arac020 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220328090022.htm

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