On minimum vital population. K voprosy o minimal/’noö jiznesposobnoï popoulyatsii. [Sur le minimum vital d’une population].

Résumé

Attempts to (re}acclimatize bobac have been made during the whole century. But it is not always a success to create an actively developing colony. We have analyzed the development of more than 40 artificial, isolated colonies. Comparing their dynamics it is possible to recognize two types of development. In one case colonies grow slowly and are on the verge of existence, and in the other case they grow sufficiently quickly. All other conditions being equal one of the reasons for such difference is the diversity of a starting genetic material. Colonies that were created by releasing a small number of introduced animals (under 50 individuals} develop slowly, as a rule. The releases of large groups of animals usually resulted in quick-growing colonies. Some animals disperse after releasing. The remainder form reproductive groups of a future colony. In both cases the dynamics of the colony growth is of an exponential character. The dynamics trends generalized as to the types of growth differ in a starting value and a growth rate. It can be assumed that to create quick-growing colonies no less than 5 family pairs are necessary. That can be achieved both by increasing the number of introduced animals, and by the measures that will favour a lower elimination of potential reproducing animals. It is obvious that a minimum starting value for a quick-growing population is 5-6 families. The growth of small colonies does not increase even after exceeding the level of 5 families. Genofond homozygosity of those colonies interferes, apparently, with their rapid growth.