PARENT SESSION
Oral Session #36: Animal Community Ecology.
Presiding: S. Simonson
Tuesday, August 6. 8:00 AM to 11:30 AM. Mesquite Room, Radisson.

On zero-sum dynamics and Taylor power laws.

Fuller, Michael^*,1, Allen, Andrew¹, ¹ University of New Mexico, Albuquerque, New Mexico

ABSTRACT- For a given species, mean abundance (A) often scales with variance in abundance (V) as a power law of the form V = a *A^b, where a is a normalization constant and b is the scaling factor. These power laws, first reported by Taylor (1961), have been observed for diverse taxa and environments. However, the mechanism responsible for generating them, and their biological interpretation, remain a topic of speculation. Building on the results of Wright (1931) and Hubbell (2001), we investigate the relationship between mean and variance for populations in communities that undergo zero-sum dynamics. We show that if variation in abundance is generated entirely by stochastic processes of birth, death, and immigration, then the pooled mean and variance in abundance become asymptotically proportional to each other, i.e., b = 1. We present empirical data in support of this prediction.

KEY WORDS: Taylor, Power-Laws, Zero-Sum, Neutral-Community-Models