Evidence for social difference in the flank organ secretion of Arvicola terrestris (Rodentia: Microtinae)

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Abstract

Gas-liquid chromatographic and mass spectroscopic analysis of secretion from the flank organs of Arvicola terrestris (L.) reveals a complex mixture of long chain esters, with the possible addition of some other substances and certainly cholesterol. Each g.l.c. peak consists of a series of isomers of the particular compound.

By comparing the proportion of the total peak height contributed by individual peaks, it was possible to analyse chromatograms to identify differences in pattern of peak height proportion between the sexes, between adult and juvenile animals of each sex, between families and between populations. There is little obvious difference between the sexes but quite marked differences between adult and juvenile animals. Comparison of samples taken from a population in June, when density was low and the breeding season had just begun and September, when density was high and the breeding season was drawing to a close, showed marked differences—especially in females. Cholesterol is a very important constituent of female flank organ secretion in June but much less important in September. Families born in captivity show significant differences between chromatogram peak patterns. The occurrence of highly significant differences between populations suggests the presence of olfactory dialects. It is not known whether this is genetically or environmentally influenced.

These observations indicate the range of difference in sebaceous output found in one species of rodent, and suggest that sexual condition and group affiliation is expressed in glandular secretion thought to be used for range demarcation.

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