| description: |
Theory of life-history evolution aims at explaining and predicting values of life-history traits. The cornerstone of the theory - optimality models - often incorporate quite general phenomenological assumptions which do not rely on proximate biological mechanisms. There are cases in which such an abstract approach has been justified but there are cases where this is definitely not the case. In particular, the approach of these general theories appears to be insufficient to explain the observed values of body size in insects; i.e. it does not facilitate optimality analysis of reaction norms for size and time at maturity. To develop an optimality approach suitable for insect growth schedules, we need to pay more attention to physiology-based constraints on larval growth curves, as well as we need better knowledge about size-dependent mortality patterns. Following the approach outlined above, we ask what do larval growth curves of ecologically and phylogenetically different insect larvae have in common. The common elements - the invariants - represent the likely constraints on insect growth curves. These principles should then be incorporated in the more realistic optimality models with a stronger case-specific predictive power. Another aim is to obtain experimental data on size-specific mortality rates. Birds and pathogens will be evaluated as selective agents in this connection. In addition to the analysis of larval growth schedules, an analogous invariant approach will be applied to explain various parameters of oviposition behaviour. The study will be based on laboratory experiments with larvae and adults of different lepidopteran species. |