Matching Items (3)
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- All Subjects: Foraging
- Creators: Foltz-Sweat, Jennifer
- Creators: Gerber, Leah R.
Description
Niche variation among sexes and life stages within a population has been documented in many species, yet few studies have investigated niche variation within demographic groups or across ecological contexts. We examined the extent to which pregnant California sea lions (Zalophus californianus) at each of three breeding colonies target alternative prey resources and habitats. The three colonies are distributed across distinct regions of the Gulf of California, Mexico and have divergent population dynamics. We compared the nature of niche variation among colonies and investigated the fitness consequences of different foraging strategies within each colony. We analyzed the δ13C and δ15N values from fur collected from 206 suckling pups to characterize relative maternal foraging locations (δ13C) and trophic levels (δ15N) during the metabolically demanding late stages of gestation and lactation that occur simultaneously in California sea lions. The δ13C and δ15N values were regressed against pup body condition index values to compare the relative individual-level fitness benefits of different maternal foraging strategies. We found that the nature and extent of niche variation differed among colonies. Niche variation was most pronounced at the two largest colonies that appear to experience the highest levels of intraspecific competition and the variation was consistent with habitat features. One colony (Granito) displayed two distinct foraging groups with indistinguishable median pup body condition values, whereas the second (San Jorge) exhibited continuous niche variation and pup body condition varied in relation to maternal foraging location and trophic level, suggesting disparities among alternative foraging strategies. For the smallest colony (Los Islotes), females occupy similar niches with a few outliers. Body condition values of pups at this colony were most variable, but did not vary with maternal foraging strategy. Our results provide evidence for intrapopulation niche variation among demographically similar individuals during a period of high metabolic stress and reproductive importance. This work suggests possible fitness benefits conferred by alternative foraging strategies, and calls into question the common assumption that members of a population are ecologically equivalent. Future research aimed at understanding animal foraging strategies should consider the nature and extent of niche variation in the context of local ecological conditions.
ContributorsCrawford, Tara Gancos (Author) / Gerber, Leah R. (Thesis advisor) / Ogle, Kiona (Committee member) / Kurle, Carolyn M (Committee member) / Arizona State University (Publisher)
Created2013
Description
One can argue that bees are the most unique insects in the animal kingdom due to their invaluable services they provide on a global level. Their importance goes beyond their capability of pollination; it is shown in their environmental impact and maintenance of the world's food supply. It is evident that the bee population is experiencing a serious and rapid decline that has resulted in changes to ecosystems in the past couple of decades. In order to resolve these issues, further research must be conducted to understand what humans can do to benefit their species' longevity. It is necessary for knowledge regarding bees, specifically their foraging behavior, to improve so humans can understand their essentiality to not only them, but the world. The focus of this study is to address any differences in foraging behavior between Apis mellifera, the honey bee, and native bee species. Other questions were answered including: do native and non-native bees have floral host preferences? Do native and non-native bees visit a variety of floral hosts? Experimental procedures were conducted to address these questions, which involved netting bees at differing times in four varying garden locations at the Desert Botanical Garden in Phoenix, Arizona. Then, the preparation of bee pollen and plant pollen slides along with bee mounting was performed. After the completion of data analysis, it was discovered that the preliminary data showed different foraging behavior between native and non-native bee species. Further studies are pertinent in obtaining statistically significant data due to an insufficient sample proportion. This is crucial in understanding the true differences in behaviors between both bee species.
ContributorsPerez, Czarinabelle Eunice (Author) / Foltz-Sweat, Jennifer (Thesis director) / Sweat, Ken (Committee member) / School of Social and Behavioral Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-12
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