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- All Subjects: Stingless bees
- Creators: Harrison, Jon F.
Description
Body size plays a pervasive role in determining physiological and behavioral performance across animals. It is generally thought that smaller animals are limited in performance measures compared to larger animals; yet, the vast majority of animals on earth are small and evolutionary trends like miniaturization occur in every animal clade. Therefore, there must be some evolutionary advantages to being small and/or compensatory mechanisms that allow small animals to compete with larger species. In this dissertation I specifically explore the scaling of flight performance (flight metabolic rate, wing beat frequency, load-carrying capacity) and learning behaviors (visual differentiation visual Y-maze learning) across stingless bee species that vary by three orders of magnitude in body size. I also test whether eye morphology and calculated visual acuity match visual differentiation and learning abilities using honeybees and stingless bees. In order to determine what morphological and physiological factors contribute to scaling of these performance parameters I measure the scaling of head, thorax, and abdomen mass, wing size, brain size, and eye size. I find that small stingless bee species are not limited in visual learning compared to larger species, and even have some energetic advantages in flight. These insights are essential to understanding how small size evolved repeatedly in all animal clades and why it persists. Finally, I test flight performance across stingless bee species while varying temperature in accordance with thermal changes that are predicted with climate change. I find that thermal performance curves varied greatly among species, that smaller species conform closely to air temperature, and that larger bees may be better equipped to cope with rising temperatures due to more frequent exposure to high temperatures. This information may help us predict whether small or large species might fare better in future thermal climate conditions, and which body-size related traits might be expected to evolve.
ContributorsDuell, Meghan (Author) / Harrison, Jon F. (Thesis advisor) / Smith, Brian H. (Thesis advisor) / Rutowski, Ronald (Committee member) / Wcislo, William (Committee member) / Conrad, Cheryl (Committee member) / Arizona State University (Publisher)
Created2018
Description
Anoxia tolerance is strongly correlated with tolerance to heat, desiccation, hyperosmotic shock, freezing, and other general stressors, suggesting that anoxia tolerance is broadly related to stress tolerance. Age affects the capacity of many animals to survive anoxia, but the basis to this ontogenic variation is poorly understood. We exposed adult Drosophila, 1, 3, 5, 7, 9, and 12 days past eclosion, to six hours of anoxia and assessed survival 24-hours post-treatment. Survival of anoxia declined strongly with age (from 80% survival for one-day-old flies to 10% survival for 12 day-old-flies), a surprising result since adult fly senescence in Drosophila is usually observed much later. In anoxia, adenosine triphosphate (ATP) levels declined rapidly (< 30 min) to near-zero levels in both 1 and 12-day old adults; thus the higher anoxia-tolerance of young adults is not due to a better capacity to keep ATP elevated. Relatively few physiological parameters are reported to change over this age range in D. melanogaster, but gut bacterial content increases strongly. As a partial test for a causal link between bacterial load and anoxia tolerance, we replaced food daily, every third day, or every sixth day, and assayed survival of six hours of anoxia and bacterial load at 12 days of age. Anoxia tolerance for 12-day old flies was improved by more food changes and was strongly and negatively affected by bacterial load. These data suggest that increasing bacterial load may play an important role in the age-related decline of anoxia tolerance in Drosophila.
ContributorsSargent, James (Author) / Harrison, Jon F. (Thesis advisor) / Haydel, Shelly (Committee member) / Lake, Douglas (Committee member) / Arizona State University (Publisher)
Created2020