Summary - Inquiline Communities

Summary - Inquiline Communities

This grant was a collaboration between me and Nick Gotelli, and supported a four-year research program to expand the theory of community assembly from its current base of correlative inferences to one grounded in process-based conclusions derived from controlled field and laboratory experiments. Northern pitcher plants, Sarracenia purpurea, and their community of inquiline arthropods and rotifers, were used as the model system for the proposed experiments.

There were three products of this research project:

1. We began the development of invertebrate assemblages that colonize pitcher plants as a model system for understanding community assembly and persistence;
2. We used field and laboratory experiments to elucidate causes of invertebrate community colonization, assembly, and persistence, and the consequences of food webcommunity dynamics for plant leaf allocation patterns, growth, and reproduction, as well as within-plant nutrient cycling. Reciprocal interactions of plant dynamics on food web structure were also investigated experimentally.
3. We began the development of matrix models to describe reciprocal interactions between food web assembly and persistence, and their living host habitat.

As an integrated whole, the proposed experiments and models began to provide a picture of linkages between pitcher-plant food webs and their host plants, at individual leaf and whole-plant scales. This focus on measures of plant performance filled an apparent lacuna in prior studies of pitcher plant microecosystems, which, with few exceptions, have focused almost exclusively on invertebrate population dynamics and interspecific interactions. Plant demography of S. purpurea was described and modeled for the first time. Complementary, multi-year field and greenhouse experiments revealed effects of soil and pitcher nutrient composition on leaf allocation, plant growth, and reproduction. Press and pulse field experiments illustrated effects of leaf age and size on food web colonization and persistence. We began to develop Markovian models of food web assembly and pitcher plant leaf allocation that describe these reciprocal interactions and began to integrate with a matrix model of pitcher plant growth. The results also illustrated consequences of nutrient limitations in northern bogs by clarifying the relative importance of N- and P-limitation on growth of a common bog plant.

Most generally, the data gathered began our process of developing, refining, and testing a mathematical model of community assembly in a dynamic habitat. The goal for this model will be to elucidate mechanistic links among community assembly, composition, and persistence; nutrient production and transfer; leaf ecophysiology; and plant growth. The results will lead to a more general and predictive understanding of community assembly and will be applicable to many other systems in which colonizing assemblages interact with living hosts, including other inquiline systems, host-parasite interactions, and plant-herbivore communities.