Project description:We compared gene expression differences in the polytypic species complex Mus musculus (Mus musculus musculus, Mus musculus domesticus, Mus musculus castaneus and Mus musculus ssp) with that of Mus spretus via oligonucleotide microarrays representing more than 20,000 genes. Analysis of the results by two way ANOVA statistics suggests that the most genes with significant differences in expression levels among the subspecies are found in liver and kidney and the least in testis. This picture is different when one compares with Mus spretus, where the largest number of differences is found in testis. Keywords: multi-species comparison