Karyotypes of four Chinese species of field mice of the genus
Apodemus were examined, including
Apodemus chevrieri
(diploid chromosome number, 2n=48, fundamental number of autosomal arms, FNa=56),
A. draco
(2n=48, FNa=48),
A. ilex
(2n=48, FNa=48), and
A. latronum
(2n=48, FNa=48). Karyotypes of
A. chevrieri,
A. draco, and
A. ilex are reported here for the first time, providing useful information for their species taxonomy. Determining the karyotypes of all species of
Apodemus in Asia, both in this and previous studies, provides a solid overview of the chromosome evolution and species differentiation of the genus in East Asia. In addition to allopatric speciation, chromosome rearrangements likely played an important role in the formation of the four
Apodemus species groups as well as speciation within each group in East Asia. For example, increased centromeric heterochromatin in
A. latronum may have contributed to the post-mating reproductive isolation from the
A. draco-A. ilex- A. semotus
clade.
