NOVOSIBIRSK REVISITED 24 YEARS ON - CHROMOSOME POLYMORPHISM IN THE NOVOSIBIRSK POPULATION OF THE COMMON SHREW SOREX-ARANEUS L

A Robertsonian fusion polymorphism in the common shrew (Sorex araneus L.), first described in Academgorodok near Novosibirsk (western Siberi a) in 1970-72, was re-examined in 1994-95. The polymorphism in the 197 0s involved chromosome arm combinations go, jl, mp and qr, i.e. each o f these combinations was present in both a metacentric and a twin-acro centric state in the population at that time. The twin-acrocentric mor ph for go occurred at low frequency in 1970-72 and was not observed in 1994-95. The polymorphism for arm combinations jl, mp and qr was stil l observed in 1994-95 and there was no significant difference in metac entric/twin-acrocentric frequencies compared with the previous sample. This is the third well-documented example in which the chromosome pol ymorphism in the common shrew has been found to be unchanged over a pe riod of 20+ years. Although the polymorphism for qr may be associated with a chromosomal hybrid zone with a dine centre 200 km away, there i s no definitive explanation for the other polymorphisms.