The Robertsonian translocation house-mouse populations of North East Scotland: a study of their origin and evolution

Abstract

The house mice, Mus musculus, of N. F. Scotland and some of the neighbouring Orkney islands carry Robertsonian translocations (centromeric fusions). By comparing the karyotypes, mandible morphology and biochemical variation of samples from four of these populations we suggest that despite chromosonial differences the populations are closely related. Available evidence suggests that the mice may have arrived with the Vikings as early as 600 A.D. and that the chromosomal changes have occurred since then. We found no evidence that the normal, 2n = 40, mice are, by other measures, different from those with Robertsonian translocations. The evidence suggests that these populations have been isolated for a considerable period of time during which there has been a marked reduction of polymorphism and heterozygosity in the island samples, which we tentatively suggest may explain differences observed in the chromosomal evolution of the four populations.

Behavioural and physiological characteristics of standard and chromosomally divergent populations of house mice from the Orkney archipelago (Scotland)

“…Anthropology of these regions reveals that the inhabitants are of Norse descent and most of the trade was with Scandinavia. The earliest link likely to have introduced mice to the islands was in 600 AD (Nash et al 1983). Nowadays these islands are described as "agricultural undulations" (Berry 1985) very favourable to the house mouse.…”

“…Despite chromosomal variation, populations of mice in Orkney are closely related on the basis of mandible morphology and biochemical traits (Davis 1983, Nash et al 1983. However the protein polymorphism suggests little or no gene flow between Orkney islands over a considerable time period (Nash et al 1983).…”

“…Orkney mice are related to mice in Caithness (north-eastern Scotland) and are believed to have a common origin different from mice of southern Britain (Nash et al 1983). Moreover, two of Orkney fusions (9.12 and 4.10) are widespread in Caithness (Searle et al 1993).…”

“…However the protein polymorphism suggests little or no gene flow between Orkney islands over a considerable time period (Nash et al 1983).…”

Caithness revisited: Robertsonian chromosome polymorphism in Caithness house mice

“…To the north, three of the Orkney islands have house mice with centric fusions (Adolph and Klein, 1981;Brooker 1982;Nash, Brooker and Davis, 1983). All mice with Robertsonian chromosomes in this region share Rb(9.12) suggesting they have a common origin.…”