Turning one into five: Integrative taxonomy uncovers complex evolution of cryptic species in the harvester ant Messor "structor".

Seed harvesting ants are ecosystem engineers that shape vegetation, nutrient cycles, and microclimate. Progress in ecological research is, however, slowed down by poor species delimitation. For example, it has not been resolved to date, how many species the European harvester ant Messor "structor" (Latreille, 1798) represents. Since its first description, splitting into additional taxa was often proposed but not accepted later on due to inconsistent support from morphology and ecology. Here, we took an iterative integrative-taxonomy approach - comparing multiple, independent data sets of the same sample - and used traditional morphometrics, Wolbachia symbionts, mitochondrial DNA, amplified fragment length polymorphism, and ecological niche modelling. Using the complementarity of the data sets applied, we resolved multiple, strong disagreements over the number of species, ranging from four to ten, and the allocation of individuals to species. We consider most plausible a five-species hypothesis and conclude the taxonomic odyssey by redescribing Messor structor, M. ibericus Santschi, 1925, and M. muticus (Nylander, 1849) stat.rev., and by describing two new species, M. ponticus sp.n. and M. mcarthuri sp.n. The evolutionary explanations invoked in resolving the various data conflicts include pronounced morphological crypsis, incomplete lineage-sorting or ongoing cospeciation of endosymbionts, and peripatric speciation - these ants' significance to evolutionary biology parallels that to ecology. The successful solution of this particular problem illustrates the usefulness of the integrative approach to other systematic problems of comparable complexity and the importance of understanding evolution to drawing correct conclusions on species' attributes, including their ecology and biogeography.

Pleistocene survival on central Alpine nunataks: genetic evidence from the jumping bristletail Machilis pallida.

Mechanisms of survival during the Pleistocene glaciation periods have been studied for more than a century. Until now, molecular studies that confirmed animal survival on Alpine nunataks, that is, ice-free summits surrounded by glaciers, were restricted to peripheral areas. Here, we search for molecular signatures of inner-Alpine survival of the narrow endemic and putatively parthenogenetic Alpine jumping bristletail Machilis pallida combining mitochondrial and AFLP data from its three known populations. The mitochondrial data indicate survival on both peripheral and central nunataks, the latter suggesting that refugia in the centre of the Alpine main ridge were more widespread than previously recognized. Incongruences between mitochondrial and AFLP patterns suggest a complex evolutionary history of the species and may be explained via parallel fixation of parthenogenesis of different origins during the last glacial maximum. We suggest that the inferred parthenogenesis may have been essential for central nunatak survival, but may pose a serious threat for M. pallida in consideration of the present climatic changes.