Population Persistence Modeling

Abstract

Hierarchical demographic models are ideal for the assessment invasive species because our knowledge of nonindigenous populations are usually limited, data on demographic traits is often obtained from the species native range, these traits vary among populations, and have a high probability of varying considerably over time as the species adapts to a new environment. As is done for traditional non-hierarchical matrix models, sensitivity and elasticity analyses were used to evaluate the contributions of different life stages and parameters to population growth rate estimates. A Monte Carlo approach was used to simulate uncertainties in the sensitivity and elasticity analyses and to project future population persistence under different management strategies. We applied the hierarchical model to northern snakehead (Channa argus). We gathered key biological information on snakehead natural mortality, maturity and recruitment in its native environment. Our results suggest that ignoring hierarchy of demographic parameters in such models may result in poor estimates of population size and growth and may lead to erroneous management advice. The probability of northern snakehead population increase is considerable, which could lead to impacts on native fauna . Our elasticity analysis and prognostic analysis showed that intensive control efforts immediately prior to spawning, and/or before larval dispersal, would be more effective (and would probably require less effort) year-long control. Our study demonstrates the importance of considering the hierarchy of parameters used in demographic models assessing invasive species.

Reference

Jiao, Y., N. W. R. Lapointe, P. L. Angermeier, and B. R. Murphy. In Review. Hierarchical demographic approaches for assessing invasive species: an example using northern snakehead (Channa argus). Ecological Modelling.