Abstracts (first author)
Individual variation in behavioral plasticity and social environments
Over the last few decades, it has become evident that between-individual variation in behavior characterize a many animal taxa. There is also increasing evidence that individuals differ in their plastic response to the environment. Various adaptive hypotheses have been suggested, and empirically tested, for why natural selection might favor between individual differences in average behavior and also between individual differences in plasticity. One key hypothesis predicts that differences between-individuals in their average behavior, as well as individual differences in behavioral plasticity are favored because social interactions lead to a diverse array of social niches. The social niche hypothesis, predicts that in high competitive environments, there will be select for high behavioral differentiation between individuals and high consistency in behavioral expression (lower plasticity), in order to reduce competition. To empirically test whether patterns of between individual variation (average behavior) and within individual variation (plasticity) support the predictions of the social niche hypothesis, we studied 12 Great tit nest box populations in Southern Germany. To study the patterns of variation between-individuals and within-individuals in the different populations, we quantified aggressiveness four times during their breeding season for 610 great tit breeding attempts in a period of three years (n=2246 tests). The populations differ in average density, but also within populations density varied across years. We used this spatial and temporal variation in social environment characteristics to test whether patterns of variation between and within individuals are indeed a function of social environment characteristics. We further studied the evolutionary consequences of behavioral variation at these two levels by quantifying how the interaction between average behavior, and plastic response to the social environment affects the fitness of individuals.