Population Regulation in Animals with Complex Life-histories: Formulation and Analysis of a Damselfly Model

This chapter discusses the population regulation in animals with complex life-histories of taxa such as damselflies obscure the mechanisms of population regulation. The information suggests four plausible mechanisms of damselfly population regulation: food availability; feeding-related intraspecific interference; mortality-related intraspecific interference; and density-dependent predation. The chapter demonstrates the model represents six damselfly life-stages and their interactions with a population of aquatic prey, using coupled ordinary and delay-differential equations, which are solved numerically. Analyzing the model's behavior both in steady state and dynamically with the literature-derived parameter values, and performs sensitivity analyses. The resulting larval densities, larval stage durations, emergence rates, and general emergence pattern for the standard parameter values are in good agreement with those in the literature: the generation time slightly exceeds one year, and the emergence pattern is strongly bimodal, as observed for some I. elegans populations in the British Midlands. The chapter concludes that emergence patterns produced by the model seem to reflect the balance between forces promoting and opposing the coexistence of the asynchronous subpopulations that produce separate emergence peaks; promoting coexistence are density-dependent predation and intra-stage, mortality-related larval interference, and opposing it is interstage interference.