samedi 12 mai 2018

PhD project: Predators that eat toxic food

Supervisors: Hannah RowlandChristian Paetz, MPI for Chemical Ecology
Background: The evolution of warning colour patterns in prey that have chemical defences is an important area of research in evolutionary biology (1). Variability in the colour patterns and chemical profiles of prey is frequently documented (2, 3). In comparison to variability in prey signals, variability in the predators that respond to these signals has less often been considered and, where it has, not directly quantified (4, 5). The evolutionary dynamics of warning colour patterns will depend on the extent of (genetic) variation both in prey and in their predators (6-8). Where predators are capable of circumventing the chemical defences of prey, this often involves the evolution of elaborate mechanisms for avoiding(9), tolerating (10), or resistance to the toxic effects of the defence (11). 
Project Description: This aim of this project is to understand the molecular and physiological mechanisms that underpin avian predator’s ability to feed on chemically defended prey. You will conduct feeding studies to determine the effect of chemical defences (positive or negative) on predator behaviour and physiology. You will use transcription profiling to detect up-regulated genes associated with defence consumption, and also investigate the fate of chemical defences after ingestion in order to identify potential detoxification mechanisms and to detect possible metabolites. There is the potential to move toward In vitro enzyme/receptor assays. 
Candidate profile: We are searching for a highly motivated student with a scientific, and curiosity-driven attitude and a strong interest in interdisciplinary research combining molecular biology, chemistry, and ecology. Excellent communication skills and proficiency in written and spoken English is required. A background in biochemistry and/or molecular biology is preferable. Experience with one of more method of transcriptomics/cell culture/ HPLC or liquid chromatography coupled with mass spectrometry (LCMS-MS) would be desirable, but not absolutely necessary (training will be given).  
  1. J. Mappes, N. Marples, J. A. Endler, The complex business of survival by aposematism. Trends Ecol. Evol. 20, 598-603 (2005).
  2. M. P. Speed, G. D. Ruxton, J. Mappes, T. N. Sherratt, Why are defensive toxins so variable? An evolutionary perspective. Biological Reviews 87, 874-884 (2012).
  3. K. Summers, M. P. Speed, J. D. Blount, A. M. M. Stuckert, Are aposematic signals honest? A review. Journal of Evolutionary Biology, n/a-n/a (2015).
  4. O. Nokelainen, J. Valkonen, C. Lindstedt, J. Mappes, Changes in predator community structure shifts the efficacy of two warning signals in Arctiid moths. J. Anim. Ecol. 83, 598-605 (2014).
  5. J. K. Valkonen et al., Variation in predator species abundance can cause variable selection pressure on warning signaling prey. Ecology and Evolution 2, 1971-1976 (2012).
  6. J. A. Endler, J. Mappes, Predator mixes and the conspicuousness of aposematic signals. American Naturalist 163, 532-547 (2004).
  7. H. M. Rowland, A. J. T. Fulford, G. D. Ruxton, Predator learning differences affect the survival of chemically defended prey. Animal Behaviour 124, 65-74 (2017).
  8. C. G. Halpin, J. Skelhorn, C. Rowe, The Relationship between Sympatric Defended Species Depends upon Predators' Discriminatory Behaviour. PLoS ONE 7, e44895 (2012).
  9. L. S. Fink, L. P. Brower, Birds Can Overcome the Cardenolide Defense of Monarch Butterflies in Mexico. Nature 291, 67-70 (1981).
  10. N. M. Marples, P. M. Brakefield, R. J. Cowie, Differences between the 7-spot and 2-spot ladybird beetles (Coccinellidae) in their toxic effects on a bird predator. Ecological Entomology 14, 79 (1989).
  11. S. Mohammadi, A. H. Savitzky, J. Lohr, S. Dobler, Toad toxin-resistant snake (Thamnophis elegans) expresses high levels of mutant Na+/K+-ATPase mRNA in cardiac muscle. Gene 614, 21-25 (2017).