Differences in molar wear gradient between adult macaques and langurs

Interspecific differences in the amount and form of molar wear in nonhuman primates are only beginning to be documented and understood. The purpose of this study was to look at the wear gradient between M₁ and M₂ in a sample of macaques and langurs to determine if differences in wear gradient could be related to differences in diet. A skeletal collection of wild shot Macaca fascicularis, Presbytis cristata, and Presbytis rubicunda from the Museum of Comparative Zoology at Harvard University was examined using photogrammetric techniques. X, Y, and Z coordinates were used to compute areas of dentin exposure on the buccal occlusal surfaces of M₁ and M₂. The relationship between these variables was examined using Bartlett’s three-group method and least-squares regression. Interspecific comparisons of the resultant y intercepts indicate that (I) M. fascicularis (as compared with P. cristata or P.) has more dentin exposed on M₁ when there is none exposed on M₂, and (2) P. cristata (as compared with P. rubicunda) has more dentin exposed on M₁ when there is none exposed on M₂. Factors that might be responsible for these differences are (a) differences in dentin/enamel structure, (b) differences in molar eruption timing, and (c) differences in behavior. An unusual intercusp sequence of dentin exposure in the langurs makes precise interpretations difficult. However, at the present time, behavioral differences among the species deserve further consideration as a cause of the observed differences in molar wear gradient.     

Inbreeding effects in captive populations of ruffed lemurs

The two subspecies of ruffed lemurs (Vareica variegata variegata andVarecia variegata rubra) have been maintained in captivity since 1959 and all institutions which hold ruffed lemurs have contributed data to theVarecia International Studbook. Studbook data were used to analyze inbreeding effects on survival in both subspecies ofVarecia. Several variables, including offspring's inbreeding coefficient, litter size, mother's inbreeding coefficient, and mother's age, were examined for significant associations with percent survivorship per litter. Percent survivorship per litter was negatively correlated to the offspring inbreeding coefficient in the black and white ruffed lemurs (p<0.001) but no significant association was found for red ruffed lemurs. Although emphasis has been put towards the status of the red ruffed lemurs due to the small founder size, the black and white ruffed lemurs should also be managed with care due to the lower tolerance to inbreeding in captivity.