The Influence of Early Olfactory Experience on Mate Choice in Mammals: Evolutionary Aspects

Abstract

The present review addresses the results of behavioral studies in cross-fostered rodent pups and the evolutionary significance and consequences of imprinting and early olfactory experience. The ability to assess the degree of relation to a potential mate can prevent inbreeding and the associated accumulation of deleterious mutations. Rodents are capable of recognizing related individuals by smell. This ability is formed in postnatal ontogenesis as a result of different mechanisms: “preassociation” and phenotypic correlation. The ability to distinguish representatives of their own and closely related species forms at an early age and is the basis for precopulative isolation mechanisms. Some mammals show an altered response to the odor of conspecifics after being fostered by individuals of other species, whereas other mammalian species do not show these changes. Certain features of odor response modification by early olfactory experience are species- and sexspecific. The critical period of behavioral reaction modification in response to odors occurs during the synaptogenesis period, which is indicative of the possible formation of new neuronal connections and synapses under the influence of early olfactory experiences. Certain behavioral and physiological responses were shown to be autonomous, as had an innate character and could not be altered by olfactory experience, whereas the others could change. The results of the studies, taken in their entirety, indicate a high degree of plasticity in the mammalian olfactory system, especially during short, sensitive developmental periods.