Ice cage: new records and cryptic, isolated lineages in wingless snow flies (Diptera, Limoniidae: Chionea spp.) in German lower mountain ranges.

In Earth's history warm and cold periods have alternated. Especially, during the Pleistocene, the alternation between these different climatic conditions has led to frequent range expansions and retractions of many species: while thermophilic species dispersed during warm periods, cold adapted species retracted to cold refugia and vice versa. After the last Pleistocene cycle many cold adapted taxa found refuges in relict habitats in mountain ranges. One example for such a cold adapted relict is the flightless snow fly Chionea araneoides (Dalman, 1816). It can be found in lower mountain ranges of Central Europe exclusively in stone runs and stony accumulations which provide cold microclimates. Imagines develop only in winter. They have strongly restricted ranges and hence experienced strong isolation predicting that local populations may show local adaptation and hence also genetic differentiation. We investigated this for several middle mountain ranges of Germany using the COI barcoding gene. Our analyses revealed two distinct lineages, one in the Bavarian Forest and a second one in all other more northern locations up to Scandinavia. These lineages likely go back to post-Pleistocene isolation and should be studied in more detail in the future, also to confirm the taxonomic status of both lineages. Further, we confirmed former records of the species for Germany and report new records for the federal states of Saxony, Lower Saxony, Saxony-Anhalt and Thuringia. Finally, we provide the first evidence of two types of males for the species, a small and a larger male type.

Inter- and intraspecific comparison of the bacterial assemblages in the hindgut of humivorous scarab beetle larvae (Pachnoda spp.).

The larvae of scarab beetles are model organisms for studying the role of physicochemical gut conditions and intestinal microbiota in symbiotic digestion, particularly of humus. Here, we address the question of whether the enlarged hindgut paunch of Pachnoda ephippiata and Pachnoda marginata, two closely related, but allopatric species, harbors a specific bacterial microbiota. Terminal restriction length fragment polymorphism (T-RFLP) analysis revealed that in both species, the bacterial hindgut community differs strongly from that in the midgut, food soil, and fecal pellets. High intra- and interspecific similarities between the T-RFLP profiles of different larvae indicate the presence of a hindgut-specific microbiota. Nevertheless, we found a clear separation of the two species. A 16S rRNA gene clone library from the hindgut of P. ephippiata identified the major phylogenetic groups as members of the Clostridia, Betaproteobacteria, and Bacteroidetes, followed by Bacillales and Deltaproteobacteria. A comparison with a previously obtained clone library of the same species corroborates both the similarities and the intraspecific variance of the hindgut microbiota.

Cuticular hydrocarbon phenotypes do not indicate cryptic species in fungus-growing termites (Isoptera: Macrotermitinae).

In several termite species, distinct differences in the composition of cuticular hydrocarbons among colonies correspond to high genetic divergence of mitochondrial DNA sequences. These observations suggest that hydrocarbon phenotypes represent cryptic species. Different cuticular hydrocarbon phenotypes also are found among colonies of fungus-growing termites of the genus Macrotermes. To determine if these hydrocarbon differences in Macrotermes also indicate cryptic species, we sequenced the mitochondrial CO I gene from species in West and East Africa. Among individuals of a supposed species but belonging to different cuticular hydrocarbon phenotypes, the genetic distances are much smaller than distances between species. Unlike what has been observed in other termites, Macrotermes hydrocarbon phenotypes do not represent cryptic species. Our findings suggest fundamental differences in the evolution and/or function of cuticular hydrocarbons among different termite lineages.

Habitat type predicts genetic population differentiation in freshwater invertebrates.

A basic challenge in evolutionary biology is to establish links between ecology and evolution of species. One important link is the habitat template. It has been hypothesized, that the spatial and temporal settings of a habitat strongly influence the evolution of species dispersal propensity. Here, we evaluate the importance of the habitat type on genetic population differentiation of species using freshwater habitats as a model system. Freshwater habitats are either lentic (standing) or lotic (running). On average, lotic habitats are more stable and predictable over space and time than lentic habitats. Therefore, lentic habitats should favour the evolution of higher dispersal propensity which ensures population survival of lentic species. To test for such a relationship, we used extensive data on species' genetic population differentiation of lentic and lotic freshwater invertebrates retrieved from published allozyme studies. Overall, we analysed more than 150 species from all over the world. Controlling for several experimental, biological and geographical confounding effects, we always found that lentic invertebrates exhibit, on average, lower genetic population differentiation than lotic species. This pattern was consistent across insects, crustaceans and molluscs. Our results imply fundamental differences in genetic population differentiation among species adapted to either lentic or lotic habitats. We propose that such differences should occur in a number of other habitat types that differ in spatio-temporal stability. Furthermore, our results highlight the important role of lotic habitats as reservoirs for evolutionary processes and the potential for rapid speciation.