Life on the edge: diet preferences reflect adaptation to drought in Neotoma fuscipes

ABSTRACTEcological change due to habitat fragmentation and climate change can decrease population viability, especially in herbivores and the plant communities upon which they depend. Behavioral flexibility is one important adaptation to both patchy or edge habitats undergoing rapid environmental change. This is true in many generalist herbivores, whose diet preferences can vary substantially, both geographically and over time. Little is known about what plants allow generalist herbivores to respond to rapid environmental changes, and whether these responses are due to variability in diet preference in a population, or individual dietary flexibility. We investigated how the diet preferences of dusky-footed woodrats (Neotoma fuscipes) might allow them to respond to drought in a spatially heterogeneous environment. We conducted cafeteria trials on woodrats during a year of extreme drought to assess individual preferences for locally available plants compared to more drought-tolerant edge vegetation. Our results show that woodrats sample a number of plants, but tend to prefer scrub oak, a dominant plant species in the available habitat, as well as chamise- a highly drought-tolerant plant predominantly present in the surrounding edge habitat. No difference in food preferences was detected between sexes, but we found evidence for an effect based on age and proximity to edge habitat. Juveniles who lived closer to the habitat edge were more likely to consume, and consumed greater amounts of plants in cafeteria trials compared to adults and juveniles living further from the edge. In addition to oak and chamise, adults sampled large quantities of other plants such as poison oak and California buckeye, and in general included a wider array of plants in their preferred diets compared to juveniles. We conclude with a discussion of the management implications and outlook for woodrats in the Coast Range of northern California.

Molecular epidemiology ofBartonellaspecies isolated from ground squirrels and other rodents in northern California

SUMMARYBartonellaspp. are endemic in wild rodents in many parts of the world. A study conducted in two northern California counties (Sonoma and Yolo) sampling California ground squirrels (Otospermophilus beecheyi) and four other rodent species (Peromyscus maniculatus, P. boylii, P. trueiandNeotoma fuscipes) led to the isolation of small Gram-negative bacilli which were identified asBartonellaspp. based on colony morphology, polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) and partial gene sequencing. Overall,Bartonellaspp. were isolated from the blood of 71% (32/45) of the ground squirrels and one third (22/66) of the other rodents. PCR–RFLP analysis of thegltA and 16S rRNA genes yielded seven unique profiles, four for the ground squirrels and three for the other rodents. Isolates from each PCR–RFLP profiles were submitted for partial sequencing. Ground squirrel isolates were most closely related toB. washoensis, whereas the other rodent isolates were closest toB. vinsoniisubsp.vinsoniiandB. vinsoniisubsp.arupensis. Two of these three species or subspecies are known zoonotic agents.