As expected, the period of the six month from April 2000 until September 2000 was too short to solve all the problems outlined in the sabbatical proposal. I concentrated on developing a theoretical framework to study reversible plastic responses with the concept of environmental tolerance that describes the change of fitness of an individual depending on an abiotic or biotic environmental state (like temperature or intensity of predation). The mode of the tolerance curve and the breadth of adaptation are both treated as complex quantitative traits. Its genetic and plastic components can be calculated by maximizing the long term geometric mean fitness. Important parameters are the time span needed to perform the plastic response, the time span for which a plastic response is advantageous, and the coefficient of variation of the environmental state.
Because of an unexpected scaling of the relative fitness (plastic to non-plastic) I was able to find and to prove analytical solutions for most cases I studied in detail. As reference point I always calculated optimal trait values and resulting fitness for non-plastic genotypes. Then I looked for the advantage of reversible plasticity in the mode and/or the breadth of adaptation depending on the model parameters for two extreme cases. First, I assumed complete information, that means that the organism has a perfectly reliable cue. Second, I assumed very incomplete information, that means a cue is used to perform a reversible plastic response but the actual optimal response remains unknown so that the cue induces always the same plastic response shaped be the long term environmental variation.
The mathematical description of the theory is almost complete. I discussed already some of the unexpected results with other resident scientists. A working group in April 2001 will elaborate in depth the ecological consequences of this theory, prepare its publication, and discuss and coordinate further lines of experimental and theoretical research on phenotypic plasticity and inducible defenses.
I was very much impressed by the variety and the high standard of working
groups and research performed by postdocs and other center fellows. My
work was inspired by the exciting atmosphere at NCEAS and I had many very
valuable interactions with participants of working groups and resident
scientists. I wish that also in Europe such highly efficient and influential
ecological research could be established.