Variation in Features of the Cranium of the Musk Deer Moschus moschiferus L. in Different Phases of the Population Cycle

The variation in four characters (three craniometrical and one nonmetric with supplemental bones) was investigated in 105 craniums of musk deer in different phases (depression and growth) of the population cycle from the East Sayan mountains. The duration of the cycle was 50 years, which corresponds to ten generations of animals. The results obtained show the multidirectional relation of skull sizes (craniometric variation) with phases in the population number in animals of different sexes. The variability of nonmetric characteristics of the skull is characterized by the greatest frequency of manifestation and the maximum quantity of additional bones during the phase of population depression in animals of both sexes, a gradual decrease in their quantity during the growth phase, and then complete loss of supplemental bones when there is an increase in population numbers. The revealed phene of the skull is a key cranial variation and may be used as a way for monitoring natural populations of rare and disappearing subspecies of musk deer.