Research
Phylogeny and evolution of the grassland crickets
One of the major projects of the Entomology Department is the study of the evolution of wasteland grasshoppers, mainly with phylogenetic and phylogeographic, but also with morphological and behavioural methods. Our results so far have shown that the evolution of this group is very complex and that various processes have led to its high species richness. Our analyses have shown, for example, that the differentiation of the Nearctic and Palaearctic genera can be traced back to a single colonisation across the Bering Strait. In both regions, convergence has resulted in a similar appearance. The speciation processes in the Palaearctic are in many cases due to glacial refugia. However, there are also many island endemics whose biogeographical history is marked by multiple colonisations and extinction events. In the genus Trimerotropis in North and South America, landscape changes have led to diversification processes. The acoustic and behavioural differentiation of many species contributes to the maintenance of species boundaries. In the future, we plan to deepen our studies at the genomic level.
Important publications:
- Husemann, M., Habel, J. C., Namkung, S.J., Hochkirch, A., Otte, D., Danley, P.D. (2015) Molecular evidence for an Old World origin of Galapagos and Caribbean grasshoppers (Acrididae: Oedipodinae: Sphingonotus). PloS One 10: e0118208.
- Husemann, M., Deppermann, J., Hochkirch, A. (2014) Multiple independent colonization of the Canary Islands by the winged grasshopper genus Sphingonotus Fieber, 1852. Molecular Phylogenetics and Evolution 81: 174-181.
- Husemann, M., Llucia Pomares, D., Hochkirch, A. (2013) A review of the Iberian Sphingonotini with description of a new species (Orthoptera: Acrididae: Oedipodinae). Zoological Journal of the Linnean Society 168: 29-60.
- Husemann, M., Confalonieri, V., Guzman, N., Danley, P.D., Cigliano, M.M. (2012) Biogeography of Trimerotropis pallidipennis (Acrididae: Oedipodinae): deep divergence within the Americas. Journal of Biogeography 40: 261-273.
- Husemann, M., Namkung, S.J., Habel, J.C., Hochkirch, A., Danley, P.D. (2012) Phylogenetic analyses of band-winged grasshoppers (Orthoptera, Acrididae, Oedipodinae) reveal convergence of wing morphology. Zoologica Scripta 41: 515-526.
Interactions of bumblebees, mites and viruses
The negative effects of Varroa mites on honey bees are well known. However, many wild bees, especially bumblebees, also frequently carry mites. These mites can theoretically also act as vectors of bee diseases. This is particularly important if the individual mite species are not specialised in one bumblebee species, as they could then also transmit pathogens between species. Our results so far show that the mites are not specialised to individual bumblebee species and that they carry honeybee viruses. Therefore, it is important to further investigate the potential for transmission of the viruses between bumblebee species to understand the potential threat they pose to our bumblebee fauna.
Biogeography of North Africa
In collaboration with Jan Habel from the TUM (Freising) we are investigating the biogeography of North Africa with a special focus on the Atlas Mountains in Morocco. Many Mediterranean species groups are particularly species-rich in North Africa and probably originated in this region. The structurally rich habitats of the region have provided optimal conditions for speciation processes and served as refugial space during the ice ages. We apply genetic and morphometric methods to species-rich groups such as scorpions and black beetles, but also grasshoppers and butterflies to understand these processes.
Important publications:
- Husemann, M., Schmitt, T., Zachos, F.E., Habel, J.C. (2013) Palaearctic biogeography revisited - Evidence for the existence of a North African refugium for western Palaearctic biota. Journal of Biogeography 41: 81-94.
- Habel, J.C., Husemann, M., Schmitt, T., Zachos, F.E., Honnen, A.-C., et al. (2012) Microallopatry Caused Strong Diversification in Buthus scorpions (Scorpiones: Buthidae) in the Atlas Mountains (NW Africa). PLoS ONE 7: e29403.
- Husemann, M., Schmitt, T., Stathi, I., Habel, J.C. (2012) Evolution and radiation in the scorpion Buthus elmouatakili (Scorpiones: Buthidae) at the foothills of the Atlas Mountains (North Africa). Journal of Heredity 103: 221-229.
- Habel, J.C., Husemann, M., Schmitt, T., Dapporto, L., Vanderwoistijne. S. (2012) A forest butterfly in the oasis of the Sahara desert: isolation does not matter. Journal of Heredity 104: 234-247.
Genetic time series
Population and conservation genetic studies usually involve only single sampling and therefore represent only snapshots of evolution. The analysis of genetic time series allows changes in genetic diversity to be analysed directly. In addition, time series can be used to calculate effective population sizes, allowing us to estimate the status of a population and the effect of drift. We use our rich collections as a resource and our modern laboratories to collect genetic data for populations that we also sample recently. The data allow us to draw conclusions about the influence of human activities on the genetic diversity of our native insect fauna.
Important publications:
- Husemann M, Zachos FE, Paxton RJ, Habel JC (2016). Editorial: Effective population size in ecology and evolution. Heredity 117: 191-192.
- Cousseau L, Husemann M, Vangestel C, Lens L (2016) Spatiotemporal analyses of demography in a declining population of house sparrows. Heredity 117: 259-267.
- Husemann, M., Cousseau, L., Borghesio, L., Lens L., Habel, J.C. (2015) Effects of population size and isolation on the genetic structure of the East African Mountain White-eye Zosterops poliogaster (Aves). Biological Journal of the Linnean Society 114: 828-836.
- Husemann, M., Cousseau, L., Callens, T., Matthysen, E., Vangestel, C., Durand, E.Y., Hallmann, C., Githiru, M. & Lens L. (2015) Post-fragmentation population structure in a cooperative breeding Afrotropical cloud forest bird: emergence of a source-sink population network. Molecular Ecology 24: 1172-1187.
- Husemann, M., Nguyen, R., Ding, B., Danley, P.D. (2015) A genetic demographic analysis of Lake Malawi rock-dwelling cichlids using spatio-temporal sampling. Molecular Ecology 24: 2686-2701.
- Habel, J.C., Husemann, M., Finger, A., Danley, P.D., Zachos, F.E. (2014) The relevance of time series in molecular ecology and conservation biology. Biological Reviews 89: 484-492.
Sequencing of type material
Types are the archetypes of species. They serve as references for taxonomic revisions and redescriptions. However, these special individuals are still mostly not genetically accessible, which means that the ultimate references in barcoding studies are generally lacking. We want to close this gap. We are trying to sequence old type material with innovative genetic methods. We are currently testing different DNA extraction methods and designing new primers exemplarily for scorpion types stored in alcohol.
Taxonomy and systematics as well as biology and biogeography of the Trichoptera (caddisflies)
In the scientific entomological collections of the ZMH, the Trichoptera collection Ulmer occupies a place of special value. New and further processing of the material includes the designation of lectotypes, new descriptions from previously undetermined material and the optimisation of the collection from a curatorial point of view.
Smaller projects in entomology deal with the biogeography of specific caddisfly species or specific areas in northern Germany. Work on the systematics and phylogeny of Trichoptera is being planned.
Digitisation and visualisation of collection material (especially types)
Scientific collections represent an inexhaustible database for numerous scientific and applied questions. In order to make this database available to as many users as possible, data (finding data, taxonomic position, etc.) are digitised and individual important representatives (primarily type material) are visualised using modern imaging techniques (3D photography, confocal imaging). In addition, up-to-date type catalogues are compiled for the various insect groups.