Wednesday, August 9, 1:30-5:00 pm
OOS 9 - Niche verses neutral: a look at an iconic idea in community ecology, its challenger, and the middle ground, Part II
Ballroom C, Ballroom Level, Cook Convention Center
Organized by: A Ostling (nsanders@utk.edu), NJ Sanders, and J Lake

In this organized oral session we will explore the latest advances in our understanding of how communities assemble, focusing on the ongoing debate over niches versus neutrality and keeping an eye towards finding the middle ground.

Ecological niches and drift combine to determine temporal and spatial aspects of food web assembly.

Chase, Jonathan*,1, 1 Washington University, St. Louis, MO

ABSTRACT- While the neutral theory can not explain a majority of patterns and processes in ecological communities, traditional niche theories also fall short in a variety of their predictions. A burgeoning synthesis, much like that accomplished decades ago in population genetics, combines the roles of ecological drift caused by stochastic factors inherent to neutral models with ecological niches and trade-offs. In fact, many important insights into this synthesis have come from borrowing population genetic concepts. However, ecological systems differ dramatically from genetic systems in that (among other things), species interactions can be competitive, predatory (or parasitic), or mutualistic, whereas allelic interactions are only competitive. This simple fact greatly undermines a unified theory that only considers competitive interactions. Here, using a combination of theoretical predictions and empirical data from pond communities, I show that the role of ecological niches and stochasticity in determining community assembly can differ substantially when a food web perspective is taken when compared to a simple competitive perspective. Specifically, I find that the presence of top predators (whose own assembly can be stochastic or deterministic) can alter the importance of stochasticity and drift in the assembly of their prey populations.

Key words: community assembly, food web, pond

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