Daily Increments on the Incisor Surface in Rodents: Intra-and Interspecific Variations

Abstract

Investigation of the incisors of 17 rodent species from 11 genera revealed substantial interspecific and intraspecific variations in the pattern of the daily increment on the incisor surface. The morphology of daily increments is described in detail. Interspecific variations in the pattern are correlated with interspecific variations in the daily activity rhythms in rodents. Intraspecific (up to individual) traits can be attributed to intraspecific (up to individual) differences in daily activity. We can conclude that the daily activity of an individual determines the pattern of its incisor growth rhythm, not being a direct cause of daily increment formation. Thus, the pattern of the increment on the incisor surface can be considered as recording the rhythm of the daily activity of a rodent during the period of incisor renewal.