1022-7954/97/3305- $18.00 © 1997 åÄàä ç‡Û͇ /Interperiodica Publishing 0562 Russian Journal of Genetics, Vol. 33, No. 5, 1997, pp. 562–567. Translated from Genetika, Vol. 33, No. 5, 1997, pp. 674–680. Original Russian Text Copyright © 1997 by Milishnikov, Saveljev, Likhnova. INTRODUCTION In the 1920s, only small aboriginal populations of European beaver (Castor fiber L., 1758) remained in the Soviet Union. They inhabited remote regions of Belarus, western Siberia, central Asia, and probably Voronezhskaya oblast. Before they were first reintro- duced into Russia in 1934, the beavers were released in Latvia, Ukraine, and Poland. The peak of reintroduc- tion was in the 1950s–1960s [1]. At the first stage, beavers from populations of Vor- onezhskaya and Minskaya oblasts served as initial material for reintroduction. Their daughter populations and mixed populations (formed after introduction of beavers from both oblasts) were used for subsequent reintroductions. At present, isolated beaver populations that mainly derived from Voronezhskaya and Belarussian popula- tions inhabit the European part of the former Soviet Union. Identification of the taxonomic status of these reintroduced (especially mixed) populations is difficult for the following reasons. First, Voronezhskaya and Belarussian populations probably belong to different subspecies [2, 3]. Second, changes in environmental conditions cause adaptive morphogenesis in introduced populations [4, 5]. Third, the level of genetic differ- ences between aboriginal populations and between aboriginal (maternal) and derivative daughter popula- tions is not known. In the previous work [6], we studied genetic varia- tion in different samples of European beaver. The bea- vers examined were kept in cages at the Voronezh State Reservation. One sample represented beavers caught in the Usmanka River (tributary of the Voronezh River). However, the number of protein systems stud- ied was low (only blood proteins). Moreover, estimates of polymorphism and mean heterozygosity obtained in [6] could differ from real values of these parameters in natural populations, because keeping animals in captiv- ity could promote selection. In this work, we expanded the number of loci stud- ied (loci for liver, kidney, and heart proteins) and com- pared Belarussian and Voronezhskaya populations (the main initial material used for reintroduction) with a beaver population introduced in Kirovskaya oblast. MATERIALS AND METHODS (1) Berezina is a sample from an aboriginal popula- tion of European beaver (Castor fiber) inhabiting the Berezina River (a right tributary of the Dnieper) within the Berezina State Reservation, Minskaya oblast and Vitebskaya oblast, Belarus. The population is charac- terized by high density and low mortality due to favor- able natural conditions and laws against hunting. In the reservation, all beavers have brown fur. We analyzed six beavers caught or shot in July–October, 1994. (2) Cheptsa is a sample from a population of Euro- pean beaver inhabiting regions near the Cheptsa River within the Research Experimental Hunting Station of the All-Russia Research Institute of Hunting and Ani- mal Breeding for Furs, Kirovskaya oblast. The popula- tion was formed in the 1960s–1970s by several intro- ductions of Belarussian and Voronezh beavers. They are hunted regularly. The population has a medium den- sity and mosaic spatial structure with regard to fur color. Some families consist completely of melanistic or brown individuals. We studied six beavers caught in October 1993–February 1994. Five of them, members of one family, were caught downstream the Svetlitsa River (a right tributary of the Cheptsa River). The sixth beaver was caught 10 km from the others in another small tributary of the Cheptsa River. (3) Voronezh is a sample of a natural population of European beaver from the Usmanka River, Voronezhs- Allozyme Variation in European Beaver (Castor fiber L., 1758) Inhabiting Berezina and Cheptsa Rivers A. N. Milishnikov 1 , A. P. Saveljev 2 , and O. P. Likhnova 1 1 Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, 117071 Russia 2 All-Russia Research Institute of Hunting and Animal Breeding for Furs, Kirov, 610601 Russia Received February 29, 1996 Abstract—The total level of allozyme variation in European beaver was first estimated by means of electro- phoretic analysis of 52 loci controlling blood, liver, kidney, and heart proteins. Variation levels in two aboriginal populations were close to that of an introduced population. Analysis of several loci showed that the introduced population originated from different stocks. On the basis of comparison of the genetic distances between dif- ferent populations of European and Canadian beavers, a hypothesis on the subspecies taxonomic status of the populations from Berezina and Voronezh rivers was advanced. ANIMAL GENETICS