Shay Callahan

PhD Student

 

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Animal Evolutionary Ecology
Institute for Evolution and Biodiversity
Hüfferstr. 13
D-48149 Münster, Germany
Tel.: +49 251/83-21653
scallaha@uni-muenster.de

Nationality: USA

Education

  • Since 2022:
    PhD studies in the Animal Evolutionary Ecology Group, Institute for Evolution and Biodiversity, University of Münster, Germany
  • 2021:
    Masters of Science, Natural Resources and Environmental Sciences (M.Sc.), University of Illinois at Urbana-Champaign, USA
  • 2017:
    Bachelor of Science in Biology and Geoscience (B.Sc.), Hobart and William Smith College, Geneva, NY, USA
  • 2016:
    Study Abroad, James Cook University, Townsville, Australia

Supervisors

  • Prof. Dr. Joachim Kurtz, Institute for Evolution and Biodiversity, Animal Evolutionary Ecology, University of Münster
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Research interests

  • tba

PhD project description

Parasites can have far-reaching ecological and evolutionary effects. However, parasites do not infect populations, species, or communities; they infect individuals. During infection, parasites construct their niches by altering their hosts’ physiology, morphology, and behaviour. Individuals often differ in their responses to the effects of parasites’ niche construction. Nonetheless, it remains unclear how those individual differences can alter the structure of natural communities, the energy flow of ecosystems, and even drive eco-evolutionary feedbacks? To address this question, we will integrate computational models and large-scale mesocosm experiments to test to what extent parasite effects on niche individualisation of their hosts mediate the widespread ecological and evolutionary effects of parasites. Using computational models, we will investigate under which conditions the individual-level effects of parasites alter individual trophic niche specialisation and eco-evo feedbacks. In mesocosm experiments, we will manipulate the density of three-spined sticklebacks (Gasterosteus aculeatus) and the presence/absence of two strains of the trophically transmitted tapeworm Schistocephalus solidus that vary in their virulence (and thus the strength of their niche construction effects). Using stable isotopes and stomach content data together with transcriptomic data, we will investigate the interactive effects of fish density and parasite virulence on stickleback niche individualisation. Furthermore, we will examine the ecological and evolutionary consequences of these effects by comparing the strength of trophic cascades and the selection regimes that a future fish and parasite generation will experience, thereby testing for eco-evo feedbacks driven by niche individualisation. This work will push the research boundaries in host-parasite interactions by illustrating how parasite traits drive host niche individualisation and shape eco-evolutionary dynamics.

Publications

  • Anaya‐Rojas JM, Bassar RD, Potter T, Blanchette A, Callahan S, Framstead N, Reznick D, Travis J (2021) The evolution of size‐dependent competitive interactions promotes species coexistence. Journal of Animal Ecology 90(11), 2704-2717. https://10.1111/1365-2656.13577 [doi]