From alleles to ecosystems and landscapes, anthropogenic activity continues to affect the environment, with particularly adverse effects on biodiversity hotspots such as Madagascar. Selective logging has been proposed as a "win-win" conservation strategy, yet its effects on different components of biodiversity are still not fully understood. Here we examine biotic factors (i.e., dietary differences) that may be driving differences in biogeochemical stocks between disturbed and undisturbed forests. We present the stable nitrogen (δ N) and carbon (δ C) isotope composition of hair from the lemur Propithecus edwardsi and of whole bodies of its obligate ectoparasite, the louse-fly Allobosca crassipes, from sites in Ranomafana National Park (RNP) that are comparable except for the history of logging and subsequent forest regeneration. P. edwardsi and A. crassipes from the disturbed (i.e., heavily selectively logged) site are lower in N and C relative to P. edwardsi and A. crassipes from sites that were minimally selectively logged or not commercially logged at all. There is a ∼3‰ decrease in N between disturbed and undisturbed sites that corresponds to a difference of nearly a full trophic level. Flowers from Bakerella clavata, a staple food source for P. edwardsi in disturbed habitats and a fallback food for P. edwardsi in primary forests, were also analyzed isotopically. B. clavata is δ N-depleted in both disturbed and undisturbed sites. Data from longitudinal behavioral surveys of P. edwardsi in RNP and other forests in eastern Madagascar point to significant differences in consumption patterns of B. clavata, with P. edwardsi in disturbed forests consuming almost twice as much of this plant. Depletion of N in animal tissues is a complex issue, but likely the result of the interaction of physiological and ecological factors. Anthropogenic disturbance in RNP from selective logging has had both biotic and biogeochemical effects that are observable trophically.
The louse fly, Allobosca crassipes (Diptera: Hippoboscidae), is an obligate ectoparasite exclusive to lemurs in Madagascar. Research in Ranomafana National Park (RNP) in southeastern Madagascar has resulted in the identification of a new association of this fly with the black and white ruffed lemur, Varecia variegata variegata, and a confirmed association with Milne-Edwards' sifaka, Propithecus edwardsi. Previous descriptions of A. crassipes were based on only a few specimens, and the type specimen is presumed destroyed. The specimens of A. crassipes collected by SJSU in 2000-2001 provide the largest collection available for the purpose of describing this species. Habitat disturbance is a major threat to the biodiversity of RNP and is predicted to affect parasite-host interactions. Disturbance has changed the behavior of the lemur hosts, which has indirectly affected the parasites. A. crassipes is found on several lemur species that rarely interact, but its low host specificity is an enigma since it is wingless as an adult. Disturbance may, however, indirectly contribute to low host specificity by forcing proximity and increasing interaction between host species. Further evidence of disturbance is seen in the isotopic composition of A. crassipes. A. crassipes-parasitizing lemurs inhabiting disturbed forests are significantly nitrogen depleted (as are their hosts) vs. those inhabiting undisturbed forests. These data further validate stable isotope ecology as a means of identifying ecosystem-wide habitat disturbance in rainforests. v ACKNOWLEDGEMENTS Many people have been involved in this project over the last several years. I
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