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Accueil du site → Doctorat → États-Unis → 1982 → OMNIVORY : ITS ROLE IN THE ECOLOGY OF DESERT CRICETINE RODENTS (MOJAVE, CALIFORNIA)

University of California, Irvine (1982)

OMNIVORY : ITS ROLE IN THE ECOLOGY OF DESERT CRICETINE RODENTS (MOJAVE, CALIFORNIA)

Eidemiller, Betty

Titre : OMNIVORY : ITS ROLE IN THE ECOLOGY OF DESERT CRICETINE RODENTS (MOJAVE, CALIFORNIA)

Auteur : Eidemiller, Betty

Université de soutenance : University of California, Irvine

Grade : Doctor of Philosophy (PhD) 1982

Résumé
The morphologically unspecialized mice of the genus Peromyscus are dietary generalists and coexist in desert habitats with rodents which have specialized morphologies and diets. This study explored the ecological ramifications of omnivorous diets upon P. crinitus and P. eremicus and community structure in a rocky outcrop habitat in the Mojave Desert, San Bernardino, California. Peromyscus was subordinate in behavioral encounters with coexisting specialist rodents. Between genera and within the genus Peromyscus dominance hierarchies followed degree of dietary specialization more closely than body size. Behavioral interactions can influence diet and habitat use in both ecological and evolutionary time. Trapping over two and one-half years showed an inverse correlation between abundance of specialists (Neotoma and Perognathus) and Peromyscus, with specialists most abundant in the summer. Peromyscus numbers increased as specialists decreased in winter. Numbers of Peromyscus also increased when competitors were removed, especially in response to the absence of Neotoma. Specialists affected microhabitat use of the generalists as well. Peromyscus were captured in low frequency in traps on the ground and rock ledges and in higher frequency in bushes and trees than expected. The specialists were primarily caught on the ground. However, with removal of either specialist, Peromyscus captures in the ground traps increased, with the removal of Perognathus having a greater effect than did absence of Neotoma. Peromyscus diets overlapped with those of both specialists, but these diets did not change significantly with removals. Generalist Peromyscus employ a combination of adaptive characteristics for survival with many specialized competitors in the desert environment. Although the physiological abilities of Peromyscus do not allow extraordinary conservation of water via urinary mechanisms, this study provides additional laboratory evidence that shallow torpor can be used to conserve energy in times of water stress. Desert Peromyscus are more likely to use shallow torpor during water deprivation than either P. maniculatus or Onychomys torridus. Versatile feeding behavior and morphology allow use of a variety of food resources and microhabitats, including those less used by specialists. Wide ranging movements of individuals and high reproductive potential allow rapid populational responses to unpredictable, changing resources.

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