1022-7954/00/3612- $25.00 © 2000 MAIK “Nauka /Interperiodica” 1431 Russian Journal of Genetics, Vol. 36, No. 12, 2000, pp. 1431–1439. Translated from Genetika, Vol. 36, No. 12, 2000, pp. 1697–1706. Original Russian Text Copyright © 2000 by Milishnikov, Lavrenchenko, Aniskin, Varshavskii. The Bale Mountains National Park, the most part of which is situated in the Bale Massif of Ethiopia at the altitude of 2000 to 4000 m above the sea level, is a unique zoogeographical complex inhabited by numer- ous endemic species. Using cytogenetic and allozyme analyses, we have shown in our previous works that some rodent species of genera Lophuromys, Stenocephalemys, Otomys, and Tachyoryctes in this park are represented by complexes of chromosome forms and biochemical types [1–4]. These studies have also revealed significant genetic dif- ferentiation among conspecific populations of species with narrow ranges. These findings suggest that the abundance and uniqueness of animal composition of the Bale Moun- tains National Park are mainly accounted for by local factors. These factors include drastic ecological changes that occurred in the past (during Pleistocene glaciation of the Bale Massif), isolated position of these mountains with regard to other mountains in Ethiopia, and extremely diverse geomorphology. Three endemic species of the species complex Lophuromys flavopunctatus sensu lato: L. chrysopus, L. brevicaudus, and L. melanonyx are most abundant in the Bale Massif and replace each other in the adjacent altitudinal belts (tropical forest–ericaceous belt– Afroalpine zone). The species rank of the former two species was shown in our previous works [2, 3, 5]. We have chosen this species complex as a main model for studying evolutionary processes in the Bale Massif. The aim of the present work was to analyze inter- and intrapopulation structure of allozyme variability in L. chrysopus, L. brevicaudus, and L. melanonyx. MATERIALS AND METHODS The Bale Mountains National Park is situated at the southeastern Ethiopian plateau (07°00' N, 39°45' E) at an altitude of 1500–4377 m above the sea level and occupies the territory of 2471 sq. km. The park includes the largest in Africa Afroalpine zone of 1000 sq. km sit- uated above 3700 m above see level. The central part of this zone is occupied by the Sanetti Plateau (200 sq. km, 3800–4200 m above sea level), which has a relatively mildly rugged topography and is covered with sparse Alpine vegetation. The territory at the intermediate alti- tude (3400–3800 m above sea level) is mainly covered by thick heather growing on the mountain slopes. The southern part of the park is occupied by the humid Harenna Forest (1500–3200 m above the sea level); in the northern part, remains of an afromontane Juniperus forest are preserved. The Bale Mountains National Park is surrounded by an agricultural zone that underwent practically total deforestation. This zone is subjected to overexploitation due to extensive cattle grazing and has strongly eroded soil. Allozyme Variability among Populations of Three Species of Brush-Furred Mice (Lophuromys, Rodentia, Muridae) from the Bale Mountains National Park (Ethiopia) A. N. Milishnikov, L. A. Lavrenchenko, V. M. Aniskin, and A. A. Varshavskii Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, 117071 Russia fax: (095) 954-55-34; e-mail: sevin@glas.apc.org Received March 29, 2000 Abstract—Allozyme variability was examined in populations of three endemic species of the species complex Lophuromys flavopunctatus sensu lato: L. chrysopus, L. brevicaudus, and L. melanonyx. These species replace each other in adjacent altitudinal belts of the Bale Massif in Ethiopia. A deficit of heterozygotes at several loci was found in most samples of all species studied. Moreover, the samples included animals homozygous for two or three minor alleles and heterozygous for alleles that are rare and unique for the given species. It is suggested that the Bale Massif are inhabited by numerous genetically isolated populations of each Lophuromys species, which exchange genes at an extremely low rate. Genotypic disequilibrium observed in most samples is explained by the fact that most sampling localities comprise ranges of two and more micropopulations. In our view, microgeographic subdivision of the populations is caused by recurrent fragmentation of habitats during the Pleistocene glaciation of the Bale Massif and subsequent prolonged isolation of local populations. Gene drift accompanying these processes resulted in high genetic differentiation of the local populations, which prob- ably persisted until the present. Geographical isolation of the Bale Massif, its uniquely diverse ecological con- ditions, and extraordinary allozyme structure of the Lophuromys populations suggest that these populations rep- resent remnants or direct descendants of relic local populations. ANIMAL GENETICS