ISSN 1022-7954, Russian Journal of Genetics, 2008, Vol. 44, No. 6, pp. 635–645. © Pleiades Publishing, Inc., 2008.
Original Russian Text © N.A. Shchipanov, N.Sh. Bulatova, S.V. Pavlova, 2008, published in Genetika, 2008, Vol. 44, No. 6, pp. 734–745.
Subdivision of a species into genetically isolated
parapatric forms is an important subject in terms of
both population genetics and evolutionary theory. The
segregation of intraspeciﬁc forms is not always
explained by external barriers. Analysis the wide natu-
ral diversity of chromosome races of the common
L.) may serve as a source of
empirical data on this and related issues. This species of
small mammals is the best object in Eurasia, including
Russia, for studying interactions at the zones of hybridiza-
tion between chromosome races with various numbers of
karyotypic differences in dozens of variations [1, 2].
Analysis of the dispersal of
races in European Russia showed that physical geo-
graphic barriers were absent in the zones where at least
some of almost 20 chromosome races come to contact
in this part of the species geographic area [3, 4].
Recently, we discovered and described the ﬁrst hybrid
zone between the chromosome races Moscow and
Seliger, which were not separated by any external bar-
rier [5, 6]. At the same time, groups with independent
population dynamics were found within the area of the
chromosome race Moscow . This raises the question
of whether there are population processes that can
themselves restrict the gene ﬂow between groups.
It is conceivable that, in the absence of geographic
barriers, the segregation of chromosome races may be
maintained by the same mechanisms that maintain
independent population dynamics. This logically leads
to the necessity of comparison between the distribution
of animals with different karyotypic characteristics at
the overlap of the contacting chromosome races in the
hybrid zone and the results of simulation of the dis-
persal of animals from different populations of the
This is the ﬁrst attempt at simulating the distribution
of common shrews on the basis of empirical data on the
distribution of the chromosome races Moscow and
Seliger and their hybrids in the hybrid zone.
EMPIRICAL POPULATION CHARACTERISTICS
The original data for estimating the characteristics
of the use of space by common shrews were collected
in an ecological station located in the Staritsa district in
southern Tver’ oblast (56
E). In this area,
observation of common shrews according was per-
formed according to the capture–mark–recapture since
1995 protocol by means of our own technique using
lines of originally designed live traps . The station
was located within the area of the chromosome race
Moscow, as was conﬁrmed by periodically testing the
animals [9, 10, our unpublished data].
Two forests, hereinafter referred to as forest 1 and
forest 3, were permanently monitored since 1995 and
1997, respectively (Fig. 1a). The area between these
forests was overgrown with deciduous forest (forest 2).
In this forest, observations were performed in 1998 and
2000–2003. IN meadows between the forests, censuses
were performed in 1996, 2001, and 2006. The traps on
the lines where monitoring was performed were always
located at the same points. The total lengths of these
lines were 1500 m in forest 1 and 750 m in each of for-
Distribution of Two Chromosome Races of the Common Shrew
L.) in the Hybrid Zone: Can a Change of the
Dispersal Mode Maintain Independent Gene Frequencies?
N. A. Shchipanov, N. Sh. Bulatova, and S. V. Pavlova
Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, 119071 Russia;
Received July 31, 2007
—Combination of different dispersal modes may itself, without external obstacles, lead to the appear-
ance of subdivided populations and maintain the existence of independent population systems. The common
shrew, a mammal convenient for studying different levels of intraspeciﬁc differentiation, was the object of the
study. Empirical data have been used for simulation taking into account the change of dispersal modes in the
population area. The obtained results agree with empirical data on the distribution of races and hybrids in the
hybrid zone of chromosome races Moscow and Seliger. Change of the dispersal mode may maintain indepen-
dent population dynamics and, in the case of chromosome races, prevent the migration of parental individuals
into the territory of the other race.
REVIEWS AND THEORETICAL ARTICLES