LARVAL COMPETITION AND GENETIC DIVERSITY IN TRIBOLIUM-CASTANEUM

The study of the relationship between genetic homogenity and intensity of competition in groups of organisms may help to explain the widespr ead existence of sexual reproduction and it can also be used to design efficient crop mixtures. To study this, we compared the survival of s ib groups and random groups of larvae of the beetle Tribolium castaneu m maintained at high population density: every group was formed by int roducing 150 eggs in 1 g of culture medium. The larvae in every group were counted weekly. The random groups survived longer, as they had mo re larvae in the last weeks. This advantage was related to a higher ea rly mortality, which reduced competition in the long run in these grou ps. Therefore, in the early stages of development, our results did not confirm the hypothesis that genetically heterogeneous groups reduce c ompetition through diversification in the use of environmental resourc es. In addition, a clear increase in between-group variability for sur vival was found in the sib groups, implying the presence of genetic va riance for competitive ability at constant initial densities in this s pecies.