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- All Subjects: Pollinator
- All Subjects: Urbanization
Description
In recent years, ecologists have begun to study the effects of urbanization on species diversity. While urban areas generally suffer decreased biodiversity, some species, termed “urban exploiters”, not only live in the city but depend on urban resources to thrive. It is hypothesized that urban exploiters may succeed in part due to phenotypic plasticity, in which organisms rapidly adjust their physiology or behavior to adapt to novel environmental contexts. In the city, it may be adaptive to display thermal plasticity, as the urban heat island effect caused by concrete and asphalt infrastructure prevents cooling at night. In this study, we observed the decorated cricket Gryllodes sigillatus, an invasive urban exploiter found in metropolitan Phoenix, in two separate experiments. We hypothesized that heat tolerance and activity are both plastic traits in this species. In Experiment 1, we predicted that knock-down time, a measure of heat tolerance, would be negatively affected by acclimation to a laboratory environment. Our results suggest that heat tolerance is affected by recent thermal regimes and that laboratory acclimation decreases knock-down time. In Experiment 2, we predicted that activity would increase with temperature until a point of extreme heat, at which point activity would decline. Statistical analysis for the second experiment reveals that activity decreases at 33°C, a natural urban extreme. This suggests either that 33°C is a thermal limit to physiology or that G. sigillatus is able to alter its behavior to exploit local thermal heterogeneity.
ContributorsVannan, Annika (Author) / Johnson, James Chadwick (Thesis director) / Angilletta, Michael (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Natural Sciences (Contributor) / School of Social and Behavioral Sciences (Contributor)
Created2015-05
Description
Honey bees are vital to human society due to their pollination services but are currently under threat due to various factors. In order to avoid drastic declines in bee populations, it is important to fully understand factors that contribute to pollinator health and efficiency. The focus of this experiment were UV markings, commonly referred to as nectar guides. While various studies have found nectar guides to influence pollinator activity, relatively few experiments have been conducted to see how UV patterns and/or UV coverage of nectar guides affects bee foraging, which is what our experiment attempted to explore. Our hypothesis was that UV coverage has a positive impact on bee foraging activity, but that full UV coverage would lower foraging activity, we also hypothesized that UV pattern would also influence foraging activity and that pollinators will prefer circular patterns. In our experiment we created artificial nectar dispensing flowers with differing UV markings and placed them out in a natural environment and recorded pollinator visitation. We then utilized a two-way ANOVA to determine if there was a statistical correlation between UV abundance and/or UV pattern on pollinator activity. Our results revealed no statistical correlation for either UV coverage (p = .389) nor UV pattern (p = .437) to pollinator activity. While no statistical correlation was found, graphical analysis of the mean between different UV groups revealed a noticeable flower preference was seen for flowers with at least some level of UV compared to no UV and a slight increase in activity for circular patterns compared to radial patterns. This suggests that perhaps UV abundance and pattern plays a minor role in pollinator activity but nothing that is statistically significant. We suggest further follow up research to improve and refine our methods and utilize a greater range of patterns and abundance size with a larger sample size to better understand the role UV pattern and UV coverage has on pollinator foraging activity.
ContributorsLazau, Joshua (Author) / Foltz-Sweat, Jennifer (Thesis director) / Sweat, Ken (Committee member) / School of Social and Behavioral Sciences (Contributor) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05