• Popular male dolphins produce more offsp

    From ScienceDaily@1:317/3 to All on Thu Mar 24 22:30:42 2022
    Popular male dolphins produce more offspring

    Date:
    March 24, 2022
    Source:
    University of Zurich
    Summary:
    The reproductive success of male dolphins is not determined by
    strength or age, but via social bonds with other males. The better
    integrated males are in their social network, the more offspring
    they produce, a new study has shown using long-term behavioral
    and genetic data.



    FULL STORY ==========================================================================
    The reproductive success of male dolphins is not determined by strength
    or age, but via social bonds with other males. The better integrated
    males are in their social network, the more offspring they produce, a
    new study by an international team of researchers led by the University
    of Zurich has shown using long-term behavioral and genetic data.


    ==========================================================================
    Male dolphins in Shark Bay, Western Australia live in complex social
    groups in which they form long-lasting bonds to cooperate with other
    males. To do this, they join in large, stable alliances. Within these alliances, males form smaller, less stable groups of two to three to mate
    with females, steal them from other alliances or defend against attacks.

    Cooperating for the purpose of reproduction "This kind of male
    cooperation for the purpose of reproduction is highly unusual in the
    animal kingdom. It's only been observed in a much less complex form
    in some other primates," says Livia Gerber, a former PhD student at
    the Department of Anthropology of the University of Zurich. Together
    with an international team led by UZH professor Michael Kru"tzen, she
    wanted to find out whether the dolphins' complex social life affects
    the reproductive success of males, or whether, as in most other species, stronger or more experienced males are more likely to sire offspring. The researchers analyzed 30 years of behavioral data from 85 male dolphins
    and used genetic data to conduct paternity analyses for more than 400
    dolphins.

    Social bonds more important than strength and age The study showed that well-integrated "popular" males with strong social bonds to many alliance partners produce the most offspring. Partner stability within the smaller, variable groups of two to three males and the age difference to alliance members, in contrast, played no role in the animals' reproductive success.

    Previous research had suggested that social bonds improve the animals'
    chances of survival, increase their longevity and lead to better immune responses and health. While all these effects might contribute to a male dolphin's lifetime reproductive success, the positive effect of social
    bond strength on cooperation was probably the key factor, according to
    first author Gerber: "Well-integrated males might be in a better position
    to harness the benefits of cooperation and access crucial resources such
    as food or mates. They may also be more resilient to partner loss compared
    to those with few, but closer partners." Long-lasting friendships improve fitness Cooperation among social partners is very common in mammals,
    but its influence on paternity success has not yet been studied in
    depth. However, understanding the factors that determine reproductive
    success and thus individual fitness is at the core of evolutionary
    biology. "Our study is the first to show that social bonds among male
    dolphins positively impact their reproductive success and are, therefore, directly linked to fitness," says senior author Michael Kru"tzen. "This
    had previously only been observed in male chimpanzees and some other
    primates. Our study expands upon previous findings on land mammals and
    provides compelling evidence that such highly complex, multi-level social systems also developed independently in the ocean."

    ========================================================================== Story Source: Materials provided by University_of_Zurich. Note: Content
    may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Livia Gerber et al. Social integration influences fitness in
    allied male
    dolphins. Current Biology, 24 March 2022 DOI:
    10.1016/j.cub.2022.03.027 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220324122506.htm

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