Europe’s mountains shaped the genetic landscape of the continent as species distributions shifted during past ice ages. As the glaciers and permafrost advanced to cover northern Europe, most species were forced to retreat to southern refugia. For many, the mountains then blocked northward dispersal as the ice melted so that different species show different patterns of recolonisation. While this has been well documented for lowland temperate species, less is known about the effect of glaciation on alpine animals. For the alpine flora, recent molecular studies have suggested refugia within the Alps and on their borders. This has implications for the community ecology of these habitats. If most animal and plant species survived in place they had a long period for coevolution and local adaptation, something not available to the more recently assembled communities of the lowlands. We will test these ideas for a genus of alpine beetles. Leaf beetles of the genus Oreina (Coleoptera: Chrysomelidae) have been well studied for their chemical defence, reproductive mode, host plant use, and patterns of local adaptation. We will establish DNA sequence-based phylogeographies for a suite of Oreina species from across the mountains of Europe. Populations will be included from the Pyrenees to the Carpathians, the Black Forest to the Apennines. Some host plants will also be analysed, using AFLP data to map their glacial refugia. These beetles are brilliantly coloured in metallic greens, blues and reds, which appears to be a warning that they possess chemical defence. Learning by predators of unpalatable prey species should produce strong purifying selection on warning colour, since only recognised patterns are avoided. Yet the genus Oreina is spectacularly polymorphic, showing geographic variation within species and multiple patterns within populations. In the second part of the project we will use species of Oreina to test the basic principles of warning colour. Using tethered individuals we can estimate survival in the wild, to test for Müllerian mimicry (resemblance between defended species) and for selection against rare patterns. The phylogeographies will provide a historical dimension in which to interpret this diversity, in the light of past and current gene flow. This project will generate a unique data set for an alpine genus, allowing us to examine how historical climate change caused communities of these beetles to migrate, to divide and to re-form. The phylogeographies will also provide a framework in which to map genetic differentiation across Europe and to study geographical variation and the evolution of host plant use, chemical defence and colour pattern.