ECOLOGY AND EVOLUTION OF THE PITCHER-PLANT MOSQUITO: 1. POPULATION DYNAMICS AND LABORATORY RESPONSES TO FOOD AND POPULATION DENSITY.

Abstract

It is commonplace to emphasize that ecological and evolutionary processes are related and ought to be studied together, but analyses of natural populations which unravel the interrelations of historical evolutionary factors, current population processes, and the prevailing effects of natural selection are not common. This is the direction of our studies of the pitcher-plant mosquito, Wyeomyia smithii. In this paper we present: the natural history and population dynamics of this species in a single bog; an experiment to determine if the larval part of the population saturates its resources at a critical time preceding metamorphosis; and studies of laboratory responses of the species to food and population density. The field data show that larval abundance is more tightly regulated (i.e., steadier) than the abundance of other parts of the life cycle. Our laboratory data show how the components of fitness are influenced by different food levels and larval density. Central in these studies is completion of the life cycle. We are trying to understand the factors which encourage or discourage completion of the life cycle and influence the average fitness of individuals under different ecological circumstances. Study of W. smithii was undertaken for a variety of conceptual and practical reasons. The ecological and evolutionary consequences of a complex life cycle (two or more distinct ecological stages) are of some interest (Istock, 1967, 1970). The species