Senescence is an intricate, multifaceted process that can vary among populations, individuals, and traits within individuals. However, the relative importance of factors generating observed differences in senescence patterns remains poorly understood. In particular, there is a lack of studies that quantify both age-dependent and state dependent components of senescence, and do so across different environmental conditions. Also, few studies have explicitly tested cumulative reproductive costs, or how early-life conditions like maternal age and state at offspring birth affect offspring adult phenotypes and senescence trajectories. I use individual-based long-term data from wild yellow-bellied marmots, to quantify chronological (age-dependent) and biological (state-dependent) senescence in female reproductive success and season-specific body mass across two different elevational environments. Since previous reproductive history could influence biological age, I also estimate costs of previous short-term and cumulative long-term reproduction on females' current reproductive success. Finally, I test whether maternal age and state at daughter birth affect daughter reproduction and senescence. I demonstrate complex senescence patterns in body mass and reproductive success. First, senescence in body mass has both age-dependent and state-dependent components, and effects are greater at lower elevation than higher elevation and greater in late summer than in spring. Second, at both elevations, females that reproduced frequently and weaned large litters in previous years have reduced current reproductive probability, while there are no short-term effects of previous reproduction. Finally, higher chronological age and closer proximity to death of the mother have positive environment-dependent effects on daughter reproductive trajectories. Overall, my findings reveal the need to investigate senescence patterns across multiple environments and over long time periods to allow capturing certain intra-individual and inter-generational effects. The persistence of maternal effects into daughters' adult lives highlights the complexity of life-history trade-offs, and calls for more studies that consider such long-term transgenerational effects when studying life-history variation and senescence in wild populations.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:731629 |
| Date | January 2017 |
| Creators | Kroeger, Svenja Brigitte |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=235411 |
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