Abstract
BackgroundStarting from Western Europe, the house mouse (Mus musculus domesticus) has spread across the globe in historic times. However, most oceanic islands were colonized by mice only within the past 300 years. This makes them an excellent model for studying the evolutionary processes during early stages of new colonization. We have focused here on the Kerguelen Archipelago, located within the sub-Antarctic area and compare the patterns with samples from other Southern Ocean islands.ResultsWe have typed 18 autosomal and six Y-chromosomal microsatellite loci and obtained mitochondrial D-loop sequences for a total of 534 samples, mainly from the Kerguelen Archipelago, but also from the Falkland Islands, Marion Island, Amsterdam Island, Antipodes Island, Macquarie Island, Auckland Islands and one sample from South Georgia. We find that most of the mice on the Kerguelen Archipelago have the same mitochondrial haplotype and all share the same major Y-chromosomal haplotype. Two small islands (Cochons Island and Cimetière Island) within the archipelago show a different mitochondrial haplotype, are genetically distinct for autosomal loci, but share the major Y-chromosomal haplotype. In the mitochondrial D-loop sequences, we find several single step mutational derivatives of one of the major mitochondrial haplotypes, suggesting an unusually high mutation rate, or the occurrence of selective sweeps in mitochondria.ConclusionsAlthough there was heavy ship traffic for over a hundred years to the Kerguelen Archipelago, it appears that the mice that have arrived first have colonized the main island (Grande Terre) and most of the associated small islands. The second invasion that we see in our data has occurred on islands that are detached from Grande Terre and were likely to have had no resident mice prior to their arrival. The genetic data suggest that the mice of both primary invasions originated from related source populations. Our data suggest that an area colonized by mice is refractory to further introgression, possibly due to fast adaptations of the resident mice to local conditions.
Highlights
Starting from Western Europe, the house mouse (Mus musculus domesticus) has spread across the globe in historic times
The source populations of the mice colonizing the small Southern Ocean islands came most likely from Western Europe, or via Atlantic
One is a very common one that was previously found in Western Europe, Cameroon and USA and occurs on other Southern Ocean islands including the Falkland Islands and Auckland Islands
Summary
Starting from Western Europe, the house mouse (Mus musculus domesticus) has spread across the globe in historic times. Domesticus invaded Western Europe about 3,000 years ago [4] and colonized the rest of the world (i.e. Africa, America and Australia/New Zealand) mostly in the wake of increased human travel across the globe that started in the 16th century [1,3,4]. They were very successful in colonizing isolated islands, such as those of the Southern Ocean [5,6,7,8,9], where they were brought by whaling ships making stops during their journeys or went for seal hunting. There was never an extended human settlement on the archipelago, but since 1951, there is a research and weather station with a continuous turnover of about 60 to 120 people per year
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