Stanisław Fedyk

Genetic differentiation of polish populations of Sorex araneus L. III : Interchromosomal recombination in a hybrid zone

Two parapatric chromosomal races of the common shrew (Sorex araneus) in Poland differ in their complement of metacentric arm combinations: hk, io, gr, nm (race IV), and hi, ko, gm, np (race II). In hybrids, these eight race‐diagnostic metacentrics form two randomly segregating complexes. The first complex (C1) occurs in the form of a ring configuration ok/kh/hi/io, or a chain o/ok/kh/hi/i (when there is Robertsonian polymorphism of the element io). The second complex (C2) always takes the form of a six‐element chain configuration r/rg/gm/mn/np/p. The C2 complex may be shortened to five or even four elements, when acrocentrics g, m and n are present. In the contact zone we found shrews of pure races (race II or IV), as well as hybrids with C1 or C2 complexes, and recombinants hi, ko, gr, nm. Complex heterozygotes are likely to suffer reduced fertility due to malsegregation at meiosis. However, the C1 hybrids with ring configurations occur with a high frequency throughout the contact zone. This suggest that their fitness is only slightly lowered relative to pure race individuals, in contrast to the hybrids with C1 or C2 chain configurations, which presumably have a more heavily reduced fertility. On the other hand, at the center of the zone there is a high proportion of recombinants, which, being chromosomal homozygotes, should display normal meiotic segregation. Furthermore, the high frequencies of recombinants within the contact zone should facilitate gene flow between the races. The occurrence of recombinants plays a similar role as the appearance of the maximum frequencies of acrocentric homozygotes described in several contact zones of S. araneus.

Karyological Analysis of Representatives of the Genus Plecotus Geoffroy, 1818 (Mammalia: Chiroptera)

SUMMARYKaryometric analysis was made of two palaearctic species of bats: Plecotus auritus and Plecotus austriacus. In both species the number of chromosomes was shown to be identical (2N=32) and also the number of arms of the chromosomes (NF = 54, NFa = 50). The relative length of chromosomes in both species are not significantly different. Significant differences, however, were found in the position of centromeres for three pairs of autosomes and X-chromosomes.On the basis of karyological comparisons of palaearctic and nearctic species of the genus Plecotus and palaeontological data, the possible ways of evolution of their karyotypes are discussed.

Cases of coat colour anomalies in the common shrew, Sorex araneus L

Coat colour anomalies in the common shrew, Sorex araneus L., in the geographical range of this species, including Poland, are extremely rare. This study describes atypically coloured common shrews. Light colouration of the coat is a result of lack ofpigment in the entire hair or hair fragments. It appears that atypically coloured shrews occur more often in isolated populations whose gene transfer with neighboring populations is limited.

Chromosome polymorphism in Polish populations of northern birch mouse Sicista betulina1

Abstract. Somatic chromosomes of 17 northern birch mice, Sicista betulina, originating from lowland and Tatra Mountain populations were studied. In the whole studied material constant diploid number of chromosomes (2n = 32) was found. Polymorphism of a pair of large-sized autosomes was found; acrocentric, subtelocentric and submetacentric chromosomes in homozygous or heterozygous state form the polymorphic pair. Consequently, chromosome arm number (NF) varies within 60 and 62. In this regard Polish populations of northern birch mouse differ from those of more eastward distribution (NF = 63–64).

Bisoniana XLV. Chromosomes of European bison, domestic cattle and their hybrids

Opisano somatyczne chromosomy Bos taurus (Fig. 1), Bison bonasus (Fig. 2) i hybrydow B1 pomiedzy bydlem a zubrem (Fig. 3). U wszystkich tych zwierząt stwierdzono modalną liczbe chromosomow N2=60, u hybrydow zaś stosunkowo wysoki procent peridiploidalnych plytek metafazalnych (Tabela 1). W dyskusji zwrocono uwage na niewystarczalnośc morfologicznych badan chromosomow gatunkow wyjściowych i hybrydow w wyjaśnieniu problemu sterylności samcow mieszancow pokolenia F.