title: Reproductive pair correlations and the clustering of organisms.
abstract: Clustering of organisms can be a consequence of social behaviour, or of the response of individuals to chemical and physical cues. Environmental variability can also cause clustering: for example, marine turbulence transports plankton and produces chlorophyll concentration patterns in the upper ocean. Even in a homogeneous environment, nonlinear interactions between species can result in spontaneous pattern formation. Here we show that a population of independent, random-walking organisms ('brownian bugs'), reproducing by binary division and dying at constant rates, spontaneously aggregates. Using an individual-based model, we show that clusters form out of spatially homogeneous initial conditions without environmental variability, predator-prey interactions, kinesis or taxis. The clustering mechanism is reproductively driven-birth must always be adjacent to a living organism. This clustering can overwhelm diffusion and create non-poissonian correlations between pairs (parent and offspring) or organisms, leading to the emergence of patterns.
authors.affiliation: Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0230, USA. wryoung@ucsd.edu
authors.forename: W R
authors.initials: WR
authors.lastname: Young
authors.forename: A J
authors.initials: AJ
authors.lastname: Roberts
authors.forename: G
authors.initials: G
authors.lastname: Stuhne
mesh_terms: D008954:Models, Biological; D009010:Monte Carlo Method; D011157:Population Dynamics; D012098:Reproduction