Evol Ecol Res 9: 375-394 (2007) Full PDF if your library subscribes.
Ecological invasion: spatial clustering and the critical radius
Andrew Allstadt,1 Thomas Caraco1* and G. Korniss2
1Department of Biological Sciences, University of Albany, Albany, NY 12222 and 2Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180-3590, USA
Author to whom all correspondence should be addressed.
Question: When localized dispersal spatially aggregates an introduced species, so that an introduction’s success or failure corresponds to growth or decay of invader clusters respectively, how does the probability of cluster expansion vary with propagation rates of locally interacting invaders and residents, with their mortality rates, and with dispersal distance?
Mathematical method: We apply the physical theory for nucleation in homogeneous spatial systems to invader–resident competition, and focus on an invader cluster’s critical radius. At the critical radius, growth and decay of an invader cluster have equal probability. Using this definition, analytically and computationally, we explore the effects of individual-level vital rates on the probability of invader-cluster growth.
Key assumptions: The two species compete preemptively for space. Invader and resident have the same mortality rate, but the invader has the greater rate of local propagation. Invader clusters are (on average) circular, and advance or decline of the invader occurs at the cluster’s perimeter.
Conclusions: The probability that an invader cluster grows, so that introduction succeeds, increases with an error function of the logarithm of the cluster’s radius. Variation in lattice-neighbourhood size has little effect on cluster-growth probability in simulation. For small differences in propagation rates, increasing the common mortality rate increases the invader’s critical radius, but may also increase the probability that large clusters invade the resident. That is, increased mortality hampers small invader clusters through chance extinction, but provides more opportunities for growth at the periphery of large clusters. The (approximate) critical radius of invader clusters scales as a power law of the difference in the two species’ propagation rates.
Keywords: cluster growth, invasive species, nucleation theory, spatial competition.
DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.
© 2007 Thomas Caraco. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.
Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.
All copies of abstracts and articles must preserve their copyright notice without modification.