Browsing by Subject "Stable Isotope"

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    Ecology And Chemistry Of Small Mammals And The Implications For Understanding Their Paleoecology And Environments
    (2015-07) Haveles, Andrew
    Fundamental goals of paleoecologists and modern ecologists is to understand the evolutionary and ecological patterns in modern and ancient biodiversity. Diet is one ecological trait species may evolve or vary to exploit food resources and increase their fitness. Stable isotope analysis is one method used to infer diet and is transferable between modern and fossil populations. Stable isotope analysis has not been commonly applied to small mammals, mostly because of sampling limitations. Here, three studies focus on furthering our understanding of small mammal ecology and serve as a baseline comparison for interpreting similar data from the fossil record. Chapter 1 illustrates that small mammals varied their diets independently and indicate granivores focused on C4 derived resources, generalists consumed resources readily available, and an invertivore focused on invertebrates. Results indicate that intermediate ?13C values between C3 and C4 resources are likely from integrating multiple resources through direct consumption and invertivory. Therefore, interpreting ?13C values from consumers in the fossil record must be interpreted with caution. Chapters 2 and 3 include a ?13C dataset that expands to the regional scale and assess how rodent partition C3 and C4 resources as C4 biomass on the landscape varies. Small mammals mostly rely on C3 derived resources, but there are some spatial and ecological tendencies with granivores incorporating the most C4 derived resources and varied with C4 biomass. Climate variables explained some variance in C4 consumption for some species, while other species' diets were not explained by climate. Seasonality metrics were the best predictors of C4 consumption and ?13C values in rodent hairs were more positive during peak C4 growing seasons. Chapter 4 estimates temperature and precipitation using the area extant species' geographic ranges overlap today and then applied to ancient faunas where the same species co-occur. Temperature and precipitation estimates for Pleistocene-Holocene localities reflect the general warming during this transition and interpolated temperature and precipitation for climate intervals illustrate deviating spatial gradients through time. The culmination of work presented here greatly improves our understanding of small mammal ecology and sets s baseline for testing modes of evolution and ecology in the fossil record.