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Mitochondrial DNA variation in British house mice (Mus domesticus Rutty)

Jones, Catherine Sue; (1990) Mitochondrial DNA variation in British house mice (Mus domesticus Rutty). Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Morphometric, karyological and historical evidence indicates that Caithness and Orkney House mice (Mus domesticus Rutty) are genetically distinct from other British mice, suggesting they are descended from introductions. Mitochondrial DNA is a small, rapidly evolving, maternally inherited molecule; hence each mtDNA molecule carries in its sequence the history of its lineage uncomplicated by recombination. Thus, mtDNA RFLPs can be used for analysing possible patterns of colonisation and gene flow in these populations. Highly purified mtDNA was isolated from each mouse and mapped, using the high resolution restriction method, with respect to the published sequence of mouse mtDNA. This allowed the types and incidence of mutational change by which mtDNA evolves in the House mouse to be evaluated. A total of 23 mtDNA composite genotypes, assayed using 14 restriction enzymes, were recognised among the British mice examined and a genetic "break" observed between individuals from the north of Britain (Orkney, Ireland and N.E. Scotland; N.W lineage) and those from the south (British mainland, south of Caithness and Sutherland; S.E lineage). The approximate location of this "break" corresponds with the Great Glen fault, which marks a boundary between inhospitable moorland, occupied by Apodemus. Geographic orientation of mtDNA variability is concordant with data from other sources, including the paternal Y-chromosome DNA. The House mouse is unlikely to have survived the last glaciation, dating tlie earliest possible British colonisation to about 10,000 B.P. An integrated approach, using evidence from anthropological, palaeontological, genetical and historical sources, permits the progression of the house mouse to be followed through Europe. These data indicate that Mas domesticus probably reached North-West Europe and Britain in the Iron Age. Hence, divergences of such magnitude between the N.W and S.E lineages are inconsistent with substitutions accumlating in situ since their arrival; consistent with the N.W and S.E forms originating from separate introduction events from different ancestral sources. Such a distinct "break" could have been maintained by a number of either extrinsic (geographical barriers) and/or intrinsic factors including, maintenance of territories, and specific mate preferences. A popular view is that house mice live in behaviourally isolated tribes or demes of between 4-6 individuals, with very little gene flow between them. It is believed that as a consequence of this rigid structure, immigrants into an establised population are unlikely to be reproductively successful, and genetic drift will become important in shaping their population structure. This concept may be too inflexible, as virtually every longitudinal study of feral mice has shown some population mixing. The Isle of May introduction experiment investigated the relative importance of these intrinsic factors. House mice from Eday (Orkney) released into an established population on the Isle of May (Firth of Forth) in April 1982, subsequently bred with the endemic mice. The relative maternal and paternal contributions to the success of this introduction were studied using mtDNA and Y-chromsome markers. Differential introgression was observed: Eday Y-chromosome apparently spread at a similar rate to the autosomal genes, while Eday mtDNA increased in incidence and distribution at only one-third the rate. The temporal and spatial distribution of Eday derived DNA showed that males disperse and introgress more rapidly than Eday females, and form a significantly higher proportion of the mating population than May males. Clearly, there seems to be no social barriers to gene flow in this feral population. The Isle of May introduction has allowed evaluation of mtDNA as a genetic marker, describing population structure and matrilineal kinship on a microgeographical scale.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Mitochondrial DNA variation in British house mice (Mus domesticus Rutty)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Biological sciences; Mutational change
URI: https://discovery.ucl.ac.uk/id/eprint/10111519
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