Functional Organization of a Population as an Approach to Studying Population Resistance: the Applied Aspect (by the Example of Small Mammals)

摘要

Responses of 14 species of small mammals (1 marsupial, 2 insectivores, and 11 rodents) to depopulation of local sites were studied. The restoration of original density in some species proceeded in accordance with reproduction rates; in others, it occurred faster than could be accounted for by reproduction; reestablishment of some populations depended on situation. The functioning of local populations determines the rate of colonization of the vacated areas. In one case, local density is controlled, while in the other case there is an excess of non-residents responsible for high rates of repopulation. These functional modes (controlling and reestablishing) are considered as alternative ones (i.e., they cannot be realized at the same time). The controlling mode of functioning corresponds to the stable composition of a local population and a relatively low share of non-residents in captures. The reestablishing mode corresponds to the variable composition of a local population and a high share of non-residents. The species studied can be classified into three groups by their capability to form local populations (sub-units) with different types of functioning. The 1st group includes species capable of forming units of both types Some species (subgroupa) can change the mode of functioning in response to some disturbance. Species of this subgroup can change the functional structure of the population in space (the fraction of the population participating in one of the alternative functions). This phenomenon is considered as a nonspecific population response, which allows species to be adapted to negative environmental dynamics. Some species can change the mode of functioning over their population cycle. They compose subgroup b. Species of this subgrouphas different resistance to impacts in various phases of the population cycle. The species with the reestablishing function compose the 2nd group, and those with the controlling one form the 3rd group. The possibilities of using species of different groups as indicators of the ecosystem state are considered. Classification of species by the above characters may be useful for implementing population control in small mammals and preventing the spread of rodent-borne diseases.