I am curious about complex ecological and evolutionary dynamics: I rummaged around tropical coral reefs, explored temperate and arctic fauna and focused during my MSc on food web dynamics and early speciation in freshwater fish. From here I naturally gravitated to the intimate, but complex interplay between parasites and hosts. I am interested in the various dimensions that impact this tight bond. I approach this with both experiments and field work. Understanding how the genetics of host and parasite, or parasite-parasite (e.g., co-infection) or host-host (e.g., inter- vs. intraspecific) interactions alter this relationship in nature where a multitude of other selection pressures are affecting it simultaneously, is deeply fascinating to me. 

Following from that, my PhD explored how the presence of a predator a) impacts parasite-mediated, MHC-based sexual selection and b) alters negative frequency dependent dynamics between host and parasite. Moreover, I aimed to understand c) the reproductive cost of mounting an adaptive immune response and d) how seasonality affects the advantage of MHC-based resistance and changes sexual selection. 

Effects of Corona and Astrovirus infections on the gut microbiomes of bats: the Hipposideros species complex as a model for virus-induced increase of pathogenic bacteria in highly gregarious mammals

As part of the Sommer Lab, I am investigating how co-infections of different Corona- and Astrovirus strains impact host health and microbiome diversity and function. For this purpose, more than 6500 tissue and faecal samples of bats belonging to the Hyposideros species complex were collected in Ghana. Initially, we will strive to decipher host species identity and population structure to uncover transmission pathways for bats recovered from different caves. Later, this information will allow us to control for phylogenetic and environmental variation. Second, we will marry infection status (e.g., AstVs/CoVs strains; mono-/co-infection) with information on the microbiome diversity and composition for each host to understand which zoonotic virus-induced population-wide microbiome changes may arise in gregarious mammals. Specially, we hope to use this data to determine whether and how the microbiome differences contribute to distinct patterns of virus replication and transmission. Besides, the host MHC, ACE2 or toll-like receptors remain of interest to fully grasp host-pathogen-microbiome interactions. Hence, this project will target some of the interactions that remained unexplored from my PhD work.
 

Fleischer R, Schmid DW, Wasimuddin, Brändel SD, Rasche A, Corman VM, Drosten C, Tschapka M, Sommer S (2022) Interaction between MHC diversity and constitution, gut microbiome composition and Astrovirus infections in a neotropical bat. Molecular Ecology, 31, 3342–3359. https://doi.org/10.1111/mec.16491

Müller-Klein N, Risely A, Schmid DW, Manser MB, Clutton-Brock T, Sommer S (2022) Two decades of tuberculosis surveillance reveal disease spread, high levels of exposure and mortality, and marked variation in disease progression in wild meerkats. Transboundary and Emerging Diseases.
https://doi.org/10.1111/tbed.14679

Risely A, Schmid DW, Müller-Klein N, Wilhelm K, Clutton-Brock T, Manser MB, Sommer S (2022) Gut microbiota individuality is contingent on temporal scale and age in wild meerkats. Proceedings of the Royal Society B, 289, 20220609. 
https://doi.org/10.1098/rspb.2022.0609

Schmid DW, Fackelmann G, Wasimuddin, Rakotondranary J, Ratovonamana YR, Montero K, Ganzhorn JU, Sommer S (2022) A framework for testing the impacts of co-infections on host gut microbiomes. Animal Microbiome, 4:48.
https://doi.org/10.1186/s42523-022-00198-5

Schwensow N*, Heni A*, Schmid J, Montero BK, Brändel S, Halczok TK, Mayer G, Fackelmann G, Wilhelm K, Schmid D*, Sommer S* (2022). Disentangling direct from indirect effects of habitat disturbance on multiple components of biodiversity. Journal Animal Ecology, 91, 2220-2234. * shared first / senior authors.
https://doi.org/10.1111/1365-2656.13802

Ferrier-Pages, C., Leal, M.C., Calado, R., Schmid, D.W., Bertucci, F., Lecchini, D., Allemand, D., (2021) Noise pollution on coral reefs? – a yet underestimated threat to coral reef communities. Mar Pollut Bull. https://doi.org/10.1016/j.marpolbul.2021.112129

Schmid, D.W., McGee, M.D., Best, R.J., Seehausen, O., Matthews, B., 2019. Rapid Divergence of Predator Functional Traits Affects Prey Composition in Aquatic Communities. Am. Nat. 193, 331–345. https://doi.org/10.1086/701784

Best, R.J., Anaya-Rojas, J.M., Leal, M.C., Schmid, D.W., Seehausen, O., Matthews, B., 2017. Transgenerational selection driven by divergent ecological impacts of hybridizing lineages. Nat. Ecol. Evol. 1, 1757–1765. https://doi.org/10.1038/s41559-017-0308-2