Despite recent advances in behavioural ecology, population consequences of adaptive behaviour remain largely unexplored. Adaptive models of scramble competition in small patches often predict an increase in competitive effort with competitor density leading to declines in the efficiency of resource usage. Such effects are ameliorated when kin are competing, and could have important consequences for population dynamics. Experimental studies have shown that bruchid beetles show many of the patterns predicted by these models, but the population consequences remain unknown. This proposal will explore the consequences of such effects for population dynamics using a combination of theoretical and experimental studies. Computer simulation models will be used to make predictions that will be tested in laboratory population cage experiments.