PACKAGING AND PROVISIONING IN PLANT REPRODUCTION

Plane reproductive ecologists investigate many aspects of reproductive design not covered by simple offspring size/number models or simple s ex allocation models, such as inflorescence design, pollen packaging o r fruit design. General models for hierarchical packaging of reproduct ive allocation which cover these and other cases are developed here. T hese demonstrate that selection will tend to equalize fitness elastici ties of reproductive components when these are properly scaled to take account of reproductive costs. Elasticities are defined as the propor tional change in a fitness component with a proportional change in the trait contributing to that component (e.g. the proportional change in the fitness per seed with a proportional change in seed size). For th e simplest reproductive design models, selection will favour the equal ization of the elasticities of all female hierarchical provisioning an d packaging fitness components or all male packaging components, both in single sex models or cosexual models. For simple cosexual models, s election favours allocation to each sex in proportion to the gender-sp ecific fitness elasticities. More generally, selection tends to equali ze all component elasticities when these are properly scaled to accoun t for the total resource costs of changes in each component. The model s are extended to cover more complex biology, including links between female and male packaging components, packaging components that contri bute to the fitness of both genders, accessory costs that may or may n ot contribute to both genders, and allometric costs and trade-offs. As assumptions about fitness interactions and life history trade-offs be come less restrictive, the models more closely approach a general equa l-marginal-advantage model. The models provide tools for understanding how and when different components of the reproductive design constrai n and selectively impact each other. The utility of the model for aidi ng in the design and analysis of specific research problems is discuss ed with reference to some empirical examples.