Peter Hammerstein: Poison-antidote systems in nature and culture

Poison-antidote systems in nature and culture

Peter Hammerstein, Institute for Theoretical Biology, Humboldt University Berlin

In host parasite interactions there is usually little scope for cooperation. It would seem maladaptive, for example, if hosts actively provided their parasites with resources, helped them tosurvive and facilitated their transmission into offspring. Intracellular bacteria of the genus Wolbachia demonstrate impressively, however, that this view of host parasite relationships is far too simple. Many strains of Wolbachia are known for a dual way in which they manipulate their hosts. In males they “poison” the sperm. In a female’s egg they offer an “antidote” if the egg is infected. Females of an infected population would then often be under selection to “pay protection money” in order to “buy” the rescue of eggs in fusions with manipulated sperm. Less figuratively speaking, our models show for a wide range of parameters that natural selection would program females to support the bacteria even if the latter significantly reduced female fecundity. This is probably one of the main reasons why more than half of all insect species seem to be infected with Wolbachia. The bacterial poison-antidote system can strongly influence host evolution since it facilitates genetic divergence, local adaptation, and speciation. Wolbachia are not the only organisms employing a poison-antidote system. In particular, human business often prospers on the basis of structurally similar manipulations. The talk also addresses the general issue of how manipulative strategies evolve and how to explain human drug seeking behavior.

Key references:

Koehncke, A., Telschow, A., Werren, J.H. & Hammerstein, P. (2009). Life and death of an influential passenger: Wolbachia and the evolution of CI-modifiers by their hosts. PLoS ONE 4(2), e4425.

Hilgenboecker, K., Hammerstein, P., Schlattmann, P., Telschow, A. & Werren, J.H. (2008). How many species are infected with Wolbachia? - a statistical analysis of current data. FEMS Microbiology Letters, 281, 215–220.

Hagen, E.H., Sullivan, R.J., Schmidt, R., Morris, G., Kempter, R. & Hammerstein, P. (2009). Ecology and neurobiology of toxin avoidance and the paradox of drug reward. Neuroscience, 160, 69-84.

Sullivan, R.J., Hagen, E.H. & Hammerstein, P. (2008). Revealing the paradox of drug reward in human evolution. Proceedings of the Royal Society of London, B, 275, 1231-1241.