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    Effects of Senescence on Reproduction and Behavior in Bottlenose Dolphins

    Cover for Effects of Senescence on Reproduction and Behavior in Bottlenose Dolphins
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    View/Open: Karniski_georgetown_0076D_14398.pdf (873kB) Bookview

    Creator
    Karniski, Caitlin Burgess
    Advisor
    Mann, Janet
    ORCID
    0000-0002-1377-5118
    Abstract
    Senescence is the degenerative change in function of all organ systems with age and is accompanied by precipitous declines in survival and fertility. In a few species, reproductive senescence culminates in menopause, the complete cessation of reproduction and a significant post-reproductive lifespan. Adaptive hypotheses for the evolution of menopause have gained recent attention. Investigating whether pathways essential to these hypotheses are also found in non-menopausal species will reveal whether these processes exclusively drive the evolution of menopause. Using a 35-year study of the bottlenose dolphins of Shark Bay, Australia, I investigate how aging affects reproduction and behavior in the context of these evolutionary hypotheses.
     
    In Chapter 1, I examine two components of reproductive senescence: fertility and maternal-effect senescence. With increasing maternal age, calf survival decreased, while lactation period increased. Interbirth intervals increased regardless of calf mortality, indicating interactions between fertility and maternal-effect senescence. Of calves that survived to weaning, last-born calves weaned latest, evidence of terminal investment.
     
    In Chapter 2, I investigate whether senescence impacts behavior in late adulthood. While time spent cycling increases in late adulthood, time spent with adult males does not change, nor do activity budgets, time spent alone, or average group sizes. Time spent socializing decreases in late adulthood when females have a dependent calf, suggesting that aging mothers regulate energy budgets in late adulthood.
     
    In Chapter 3, I explore the nature of intergenerational relationships in the context of the “grandmother” and “reproductive conflict” hypotheses for the evolution of menopause. Females do not affect survival or weaning of grandoffspring or reproductive success of daughters. However, they accelerate their daughters’ maturation, with an earlier age of first birth, dependent on grandoffspring survival. Second-generation offspring born into reproductive conflict exhibit reduced survival. These results indicate that matrilineal investment and reproductive conflict occur simultaneously in a non-menopausal species, suggesting that these processes alone do not drive the evolution of menopause. This work demonstrates how aging impacts mammalian reproduction and behavior and contributes to our understanding of the evolution of reproductive life histories
     
    Description
    Ph.D.
    Permanent Link
    http://hdl.handle.net/10822/1056029
    Date Published
    2019
    Subject
    Bottlenose dolphin; Grandmother hypothesis; Maternal investment; Menopause; Reproductive conflict; Reproductive senescence; Biology; Evolution (Biology); Aging; Biology; Evolution & development; Aging;
    Type
    thesis
    Embargo Lift Date
    2020-03-17
    Publisher
    Georgetown University
    Extent
    144 leaves
    Collections
    • Graduate Theses and Dissertations - Biology
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    • Cover for Age Determination, Life History and Juvenile Behavior in Bottlenose Dolphins (Tursiops sp.) in Shark Bay, Australia

      Age Determination, Life History and Juvenile Behavior in Bottlenose Dolphins (Tursiops sp.) in Shark Bay, Australia 

      Krzyszczyk, Ewa Beata (Georgetown University, 2013)
      Although of theoretical interest, the juvenile period in mammals is a relatively neglected area of research. In large-brained and social mammals, such as bottlenose dolphins, where juvenile periods are prolonged, life ...
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    Georgetown University Seal
    ©2009 - 2022 Georgetown University Library
    37th & O Streets NW
    Washington DC 20057-1174
    202.687.7385
    digitalscholarship@georgetown.edu
    Accessibility