ISSN:
1432-0886
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Cytogenetic studies of feral mice (M. musculus) from various but predominantly Alpine areas of Switzerland, carried out on random samples collected by spot-checks, established the widespread existence of metacentric chromosomes in the somatic karyotype. Despite the finding of the common occurrence of some of the metacentrics in different places, the examination of the possible homology or heterology by breeding procedures revealed the surprising fact that independence, partial or heterobrachial homology of the metacentric chromosomes prevail among mice from different geographical areas. Thus, the general picture is that of an array of different metacentric chromosomes derived from independent events of Robertsonian variation in the process of evolution. — While heterozygosity with independent metacentrics within a Robertsonian system may have a bearing on the fertility rate of a given mouse population, a more severe impairment of the reproductive capacity must be taken into account in mouse populations which possess different metacentrics with mono- or heterobrachial homologies. These conditions favour the assumption of the existence of a selective system of reproductive barriers further subdividing the species in many, more or less stable, micro-populations. — The chromosomal arms (telocentrics) involved in the formation of the metacentric chromosomes could be identified by Q- and G-banding techniques in combination with the results of crossbreeding, and were assigned to the corresponding telocentric autosomes of the mouse (Comm. Standard. Genet. Nomenclat. for Mice, 1972). Most of the telocentric autosomes of the mouse are included in one or more of the metacentrics found in the feral populations. By means of their isolation in separate lines, these metacentrics may be useful in experimental biology as marker chromosomes of defined identity carrying known linkage groups.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00290787
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