FROM AN AGROPHILE TO A SYNURBIST: HOW THE COMMON HAMSTER (<i>CRICETUS CRICETUS</i>) IS SETTLING INTO THE URBAN ENVIRONMENT

Abstract

In this review, using our own and published data, we discuss the processes that occur in populations of small mammals when they adapt to and master the urban environment, using the common hamster as an example. Originally, the common hamster was apparently associated with the forest-steppe zone, but with the development of agriculture, it became an agrophile, populating the outskirts of fields, which provided it with a good food base throughout the year. Changes in farming culture (fragmentary fields replaced with vast areas of arable land occupied by monocultures, the use of poisons and fertilizers) led to a shift in the ecological optimum of the species to areas occupied by gardens, kitchen gardens and urban ecosystems. This led to changes in the genetic structure of populations, a greater (compared to suburbs) diversity of alleles of the major histocompatibility complex responsible for resistance to pathogens, a reduced hibernation period up to its complete abandonment, and a reduced aggressiveness to conspecifics which allows for more burrows to be arranged in a limited space and for general food storages to be shared and consumed. The use of food wastes as an additional food resource by this species may have led to changes in its digestive and other systems. All of this has allowed the common hamster to successfully exist in an urbanized environment, despite the reduction in life expectancy due to many stressors (parasitic load, pollution etc.). It is assumed that not all of the above traits have been formed in the process of synurbization. Many adaptations acquired earlier, before urbanization, proved to be effective in its development of the urban environment. Obviously, the path taken by the common hamster from a non-commensal species to an agrophile, and finally a synurbist is not unique; many other species of mammals and birds have passed or are on this evolutionary path at the present time.