Telomere dynamics during hibernation in a tropical primate.

Hibernation is a widespread metabolic strategy among mammals for surviving periods of food scarcity. During hibernation, animals naturally alternate between metabolically depressed torpor bouts and energetically expensive arousals without ill effects. As a result, hibernators are promising models for investigating mechanisms that buffer against cellular stress, including telomere protection and restoration. In non-hibernators, telomeres, the protective structural ends of chromosomes, shorten with age and metabolic stress. In temperate hibernators, however, telomere shortening and elongation can occur in response to changing environmental conditions and associated metabolic state. We investigate telomere dynamics in a tropical hibernating primate, the fat-tailed dwarf lemur (Cheirogaleus medius). In captivity, these lemurs can hibernate when maintained under cold temperatures (11-15 °C) with limited food provisioning. We study telomere dynamics in eight fat-tailed dwarf lemurs at the Duke Lemur Center, USA, from samples collected before, during, and after the hibernation season and assayed via qPCR. Contrary to our predictions, we found that telomeres were maintained or even lengthened during hibernation, but shortened immediately thereafter. During hibernation, telomere lengthening was negatively correlated with time in euthermia. Although preliminary in scope, our findings suggest that there may be a preemptive, compensatory mechanism to maintain telomere integrity in dwarf lemurs during hibernation. Nevertheless, telomere shortening immediately afterward may broadly result in similar outcomes across seasons. Future studies could profitably investigate the mechanisms that offset telomere shortening within and outside of the hibernation season and whether those mechanisms are modulated by energy surplus or crises.

Of fruits and fats: high-sugar diets restore fatty acid profiles in the white adipose tissue of captive dwarf lemurs.

Fat-storing hibernators rely on fatty acids from white adipose tissue (WAT) as an energy source to sustain hibernation. Whereas arctic and temperate hibernators preferentially recruit dietary polyunsaturated fatty acids (PUFAs), tropical hibernators can rely on monounsaturated fatty acids that produce fewer lipid peroxides during oxidation. Nevertheless, compositional data on WAT from tropical hibernators are scant and questions remain regarding fat recruitment and metabolism under different environmental conditions. We analyse fatty acid profiles from the WAT of captive dwarf lemurs (Cheirogaleus medius) subjected to high-sugar or high-fat diets during fattening and cold or warm conditions during hibernation. Dwarf lemurs fed high-sugar (compared to high-fat) diets displayed WAT profiles more comparable to wild lemurs that fatten on fruits and better depleted their fat reserves during hibernation. One PUFA, linoleic acid, remained elevated before hibernation, potentially lingering from the diets provisioned prior to fattening. That dwarf lemurs preferentially recruit the PUFA linoleic acid from diets that are naturally low in availability could explain the discrepancy between captive and wild lemurs' WAT. While demonstrating that minor dietary changes can produce major changes in seasonal fat deposition and depletion, our results highlight the complex role for PUFA metabolism in the ecology of tropical hibernators.

Imprinting in ducklings: variability among individuals and responses.

Duck embryos show a highly variable heart rate, which remains variable, though to a lesser degree, upon hatching. After hatching, behavioral responses of ducklings in an imprinting paradigm are also variable both between ducklings, and between particular responses (behavioral inter se and behavioral vs physiological). Nonetheless, responses, when viewed multi-dimensionally, do appear to cluster, suggesting that there exist a variety of discrete developmental 'types', even among an inbred strain of ducklings.

Social Darwinism lives! (Should it?).

Sociobiology has made a resurgence in recent years, but has become enmeshed in political controversy. Indeed, much of the work in sociobiology has been used to justify repressive or racist measures. It is argued that the unfortunate alliance of some sociobiologists and politicians is a poor basis for discrediting the field itself; that a science of sociobiology is possible and, if we seek to know the nature of our social heritage (if any!), needs be vigorously pursued.

Patterns of maternal care in lemurs. III. Lemur variegatus.

Lemur fulvus, L. catta, and L. variegatus differ markedly in the details of mother-infant relations. Do these differences account for those seen in adult life? We hope to determine this through interspecific cross-fostering. Here we describe the normal pattern of rearing of 5 infants among two groups of 2 and 5 adult L. variegatus, reared in the laboratory. The descriptions cover the first 7 months of life, and include the effects of maternal separation at 150 days of age, when estrus normally disrupts maternal care. The principal finding is that in the mother's absence young turn more to other adults than to their siblings, who are, apparently, not adequate social substitutes for adults.

Migration and species diversity in the tropics.

If the young of a dominant species are subjected to disproportionately heavy predation, this, together with a limitation on food, can promote a high species diversity. This is seen among tropical birds, which are simultaneously exposed to both conditions to a far greater degree than are Temperate Zone species. Migration to the Temperate Zones during the spring provides a release from these restraints, while also precluding breeding in the Tropics.