Characterization of the Tree Holes Used by Lepilemur ruficaudatus in the Dry, Deciduous Forest of Kirindy Mitea National Park

Sleep deprivation, sleep fragmentation, and social jet lag increase temperature preference in Drosophila

Despite the fact that sleep deprivation substantially affects the way animals regulate their body temperature, the specific mechanisms behind this phenomenon are not well understood. In both mammals and flies, neural circuits regulating sleep and thermoregulation overlap, suggesting an interdependence that may be relevant for sleep function. To investigate this relationship further, we exposed flies to 12 h of sleep deprivation, or 48 h of sleep fragmentation and evaluated temperature preference in a thermal gradient. Flies exposed to 12 h of sleep deprivation chose warmer temperatures after sleep deprivation. Importantly, sleep fragmentation, which prevents flies from entering deeper stages of sleep, but does not activate sleep homeostatic mechanisms nor induce impairments in short-term memory also resulted in flies choosing warmer temperatures. To identify the underlying neuronal circuits, we used RNAi to knock down the receptor for Pigment dispersing factor, a peptide that influences circadian rhythms, temperature preference and sleep. Expressing UAS-Pdfr^RNAi in subsets of clock neurons prevented sleep fragmentation from increasing temperature preference. Finally, we evaluated temperature preference after flies had undergone a social jet lag protocol which is known to disrupt clock neurons. In this protocol, flies experience a 3 h light phase delay on Friday followed by a 3 h light advance on Sunday evening. Flies exposed to social jet lag exhibited an increase in temperature preference which persisted for several days. Our findings identify specific clock neurons that are modulated by sleep disruption to increase temperature preference. Moreover, our data indicate that temperature preference may be a more sensitive indicator of sleep disruption than learning and memory.

Feeding ecology of Lepilemur septentrionalis in the dry forest of Montagne des Français, northern Madagascar

The role of folivorous primates in ecosystem restoration has been largely overlooked. This may primarily be due to the lack of basic ecological information on many of these species. The northern sportive lemur (Lepilemur septentrionalis), for example, is one of the most endangered primates in the world, yet we lack baseline ecological knowledge of this lemur. This dearth only serves to exacerbate their situation as conservation initiatives do not have the fundamental information needed to properly manage conservation efforts for this species. To obtain an ecological baseline for L. septentrionalis, we used instantaneous focal animal sampling to collect behavioral data, including strata use, to investigate feeding ecology for five individuals over a 12-month period (December 2018-November 2019) in Montagne des Français. We conducted a total of 755.1 hours of observation. Our results showed that L. septentrionalis’ diet consisted of mature and young leaves, ripe and unripe fruits, flowers, and buds. Mature leaves of Tamarindus indica were the most frequently consumed resource, yet L. septentrionalis consumed 61 different species of plants from 23 families. Though mature leaves were the most frequently consumed resource overall, we only observed L. septentrionalis eating them during the cold/dry season. The most frequently used stratum during feeding was the canopy, which correlated strongly with the consumption of mature and young leaves. Though many aspects of this species’ diet are similar to other Lepilemur, there are specific ecological conditions, notably seasonal frugivory, which should be considered when developing restoration ecology programs in Montagne des Français.

Classifying Chimpanzee (Pan troglodytes) Landscapes Across Large-Scale Environmental Gradients in Africa

Primates are sometimes categorized in terms of their habitat. Although such categorization can be oversimplistic, there are scientific benefits from the clarity and consistency that habitat categorization can bring. Chimpanzees (Pan troglodytes) inhabit various environments, but researchers often refer to “forest” or “savanna” chimpanzees. Despite the wide use of this forest–savanna distinction, clear definitions of these landscapes for chimpanzees, based on environmental variables at study sites or determined in relation to existing bioclimatic classifications, are lacking. The robustness of the forest–savanna distinction thus remains to be assessed. We review 43 chimpanzee study sites to assess how the landscape classifications of researchers fit with the environmental characteristics of study sites and with three bioclimatic classifications. We use scatterplots and principal components analysis to assess the distribution of chimpanzee field sites along gradients of environmental variables (temperature, rainfall, precipitation seasonality, forest cover, and satellite-derived Hansen tree cover). This revealed an environmental continuum of chimpanzee study sites from savanna to dense forest, with a rarely acknowledged forest mosaic category in between, but with no natural separation into these three classes and inconsistencies with the bioclimatic classifications assessed. The current forest–savanna dichotomy therefore masks a progression of environmental adaptation for chimpanzees, and we propose that recognizing an additional, intermediate “forest mosaic” category is more meaningful than focusing on the ends of this environmental gradient only. Future studies should acknowledge this habitat continuum, place their study sites on the forest–savanna gradient, and include detailed environmental data to support further attempts at quantification.