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

Abstract

Behavioural and physiological characteristics of standard and chromosomally divergent populations of house mice from the Orkney archipelago (Scotland) Guila GANEM Ganem G. 1998. Behavioural and physiological characteristics of standard and chromosomally divergent populations of house mice from the Orkney archipelago (Scotland). Acta Theriologica 43: 23-38. (Schwartz and Schwartz, 1943) from Orkney are closely related on the basis of mandible morphology and allozyme variation. In three of the twenty islands where house mice occur populations have diverged from the standard 2n = 40 karyotype through fixation of Robertsonian (Rb) chromosomal mutations. Mice from Westray island carry 36 chromosomes and share one Rb fusion with those from Eday and Faray (2n = 34; 2n = 34-36). These islands are geographically very close to each other and to islands carrying standard mice. Behavioural and ecophysiological analyses were performed on the three chromosomally divergent populations of mice as well as on two nearby standard populations (Sanday and Papa-Westray). The aim of the study was to assess whether divergences attributable to chromosomal changes occur, and to discuss whether behavioural divergences may explain the non-mixing of karyotypes. The study does not reveal any divergence between islands attributable to karyotype or habitat differences. The non-blending of the different karyotypes present in Orkney is discussed with reference to history of colonisation, human behaviour, and the consequences of site saturation. Particular characteristics displayed by the different island-populations suggest that in the near future the present pattern of karyotype variation observed in Orkney could change. House mice Mus musculus domesticus

Chromosomal variation in the house mouse

“…Over time, the clines between the metacentrics 11.14 and 6.13 would have become separated (or ‘staggered’) from the metacentrics 9.12 and 4.10 (forming new homozygous metacentric populations), for reasons which are not entirely clear, but are probably related to hybrid fitness. This system has been studied since the early 1980s, with particular emphasis on the staggered hybrid zone (Searle et al ., 1993) and behavioural differences between metacentric populations (Ganem, 1998).…”

The effect of multiple simple Robertsonian heterozygosity on chromosome pairing and fertility of wild-stock house mice <i>(Mus musculus domesticus)</i>

“…A number of races have been described in Western Europe and Northern Africa, some with as many as eighteen metacentrics (2n = 22) such that only the smallest pair of autosomes and the sex chromosomes remain acrocentric (Gropp and Winking, 1981;Capanna, 1982;Nachman and Searle, 1995). Robertsonian fusions in house mice are not known to cause somatic effects (Ganem, 1998) but may disrupt meiosis and gametogenesis (Redi and Capanna, 1988;Searle, 1993;Hauffe and Searle, 1998) and have provided a rich source of material for cytogeneticists studying fundamental aspects of meiosis (e.g. de Boer and de Jong, 1989;Mahadevaiah et al, 1990;Tease and Fisher, 1993;Eichenlaub-Ritter, 1994).…”

Back to the wild: does feralization affect the mandible of non-commensal house mice (Mus musculus domesticus)?

“…Eight islands of the Orkney Archipelago ( Fig. 1; Table 1), located North of Scotland, were sampled during two field trips in (Eday, Faray where house mice are feral; Papa Westray, Sanday, and Westray) (Ganem, 1998) and 2012 (Orkney Mainland, Burray, Papa Westray, and South Ronaldsay). A single mouse was trapped on Burray and pooled with those from South Ronaldsay, the closest island, for all analyses.…”

“…Being trapped in slightly different environments (hay stacks in 1992 and buildings in 2012), the two samples were considered separately. All of the 1992 mice have been kept in laboratory for 3-4 months after their capture (Ganem, 1998). During the 2012 campaign, some mice from Mainland and South Ronaldsay have been sacrificed in the field while all the others, together with Papa Westray mice, were kept in laboratory.…”

“…The age of this feral population is unclear. Finally, Faray Island in the Orkney Archipelago used to sustain human settlements but the island was completely deserted in 1947 (Berry et al, 1992;Ganem, 1998). It is still used for pasture, with occasional transfer of sheep and food by small boats.…”