Maria-Denise Dearing

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Temporal stable isotope records derived from animal tissues are increasingly studied to determine dietary and climatic histories. Despite this, the turnover times governing rates of isotope equilibration in specific tissues following a dietary isotope change are poorly known. The dietary isotope changes recorded in the hair and blood bicarbonate of two(More)
Symbiotic gut microbes have facilitated the success of herbivorous mammals, which are generally grouped into foregut- and hindgut-fermenters. However, rodents are primarily herbivorous and exhibit a variety of gastrointestinal anatomies. Most rodents house microbes in hindgut chambers, such as the caecum and colon. Some rodents also exhibit stomach(More)
The challenge of consuming plant compounds that are recognized to have toxic physiological effects is an unavoidable consequence of an herbivorous diet and requires mechanisms to metabolize and eliminate them after consumption. We took a pharmacological approach to understanding how an oak (Quercus agrifolia) specialist (Neotoma macrotis) and generalist (N.(More)
Plant secondary metabolites (PSMs) significantly impact the nutritional ecology of terrestrial vertebrate herbivores. Herbivores have a wide range of mechanisms (herbivore offenses) to mitigate the negative effects of PSMs. We discuss several behavioral and physiological offenses used by terrestrial vertebrates. Several newly recognized herbivore offenses(More)
Constraints on rates of detoxification and elimination of plant toxins are thought to be responsible for limiting dietary specialization in mammalian herbivores. This hypothesis, known as the detoxification limitations hypothesis, suggests that most mammalian herbivores are generalists to avoid overdosing on toxins from a single plant species. The(More)
Detoxification capacity of enzymes in the liver is thought to be the primary factor governing dietary toxin intake by mammalian herbivores. Recently, toxin absorption in the gut was proposed as an alternative process that also influences toxin intake. We examined the role of the gut in regulating toxin absorption by quantifying excretion of a plant(More)
The ability of herbivores to switch diets is thought to be governed by biotransformation enzymes. To identify potential biotransformation enzymes, we conducted a large-scale study on the expression of biotransformation enzymes in herbivorous woodrats (Neotoma lepida). We compared gene expression in a woodrat population from the Great Basin that feeds on the(More)
A study was done to test whether toxic plants that occur naturally in the diet affect thermoregulation in mammalian herbivores. The woodrats Neotoma albigula and Neotoma stephensi both consume juniper (Juniperus monosperma), a plant with high levels of toxic compounds. Body temperature (Tb), basal metabolic rate (BMR), and the minimum cost of thermogenesis(More)
The reaction progress variable is applied to stable isotope turnover of biological tissues. This approach has the advantage of readily determining whether more than one isotope turnover pool is present; in addition, the normalization process inherent to the model means that multiple experiments can be considered together although the initial and final(More)
We sampled 143 individuals from Rancho La Brea (RLB) large faunal collections for bone collagen stable carbon (d 13 C) and nitrogen (d 15 N) isotope ratios. These collections were recovered from asphalt seeps in the Los Angeles Basin, California, USA, and date from f 40 to 12 ka. Our findings indicate that despite a slight reduction in collagen nitrogen(More)