Models of invasive species introductions, distribution and spread, and establishment are 
key tools for both understanding the invasive species problem and designing effective prevention 
and control techniques. Numerous types of models have been developed. In many cases, 
authors recommend that conservation managers be cognizant of specific factors (e.g., species 
interactions, climatic factors, spread vectors) in ecosystem management. Some authors offer 
clear, ready-to-use models and strategies for conservation managers. Table E-l below lists 
examples of models used to predict species invasions. 
Although most invasive species’ spread, distribution, and establishment models are not 
designed specifically to incorporate climate change variables, several approaches have been 
developed that do explicitly address climate change impacts on species distributions. These 
include bioclimatic envelope models, discriminant analyses, and logistic regression analyses (see 
table below—identified by an asterisk). Other modeling methods, such as ecological niche 
modeling, could be modified to integrate climate change variables. 
Table E-l. Model and description 
Comparative analysis. Ricciardi and Rasmussen (1998) use descriptive information to identify species with high 
invasion and impact potential. The three steps include (1) identifying donor regions and dispersal; (2) selecting 
potential invaders based on biological traits; and (3) using invasion history. The analysis identifies Corophium spp., 
Mysids, and Clupeonella caspia as possible Great Lakes-St. Lawrence River system invaders. The authors 
recommend focusing on monitoring and applying described guidelines, and developing an accessible electronic 
database of possible invaders. 
Comparative analysis. Vermeij (1996) recommends an agenda for invasion biology. The author supports using a 
model or approach that is more comparative and systematic that involves a framework of scientific questions that 
need to be answered. The paper does not include a scientific study; thus, no results are provided. However, the 
author recommends comparing factors involved in the invasion process (arrival, establishment, and integration), 
participants, and outcomes at spatial and temporal scales. The author prefers multiple methodological approaches to 
address invasion biology. 
Simple diffusion model. Buchan and Padilla (1999) use a simple diffusion model to predict zebra mussel spread by 
(1) comparing current pattern of zebra mussel invasion with estimates of boater movements, and (2) diffusion model 
data. The model can be used to estimate infrequent, long-distance boater movements to predict AIS invasion 
probability. Simple diffusion models are mathematical models that use variables such as population growth and 
density and velocity of the invasion front to predict temporal and spatial patterns. The authors recommend 
managers use the results to predict spread rates and patterns to use in developing management strategies for the 
Great Lakes. Efforts to curb or stop spread should focus on high frequency long-distance paths such as areas with 
high boating activity. 
Diffusion. Vanderploeg et al. (2002) describe and predict dispersal patterns and ecological impacts of five invaders 
in the Great Lakes. The authors synthesize laboratory data on the ecology of Ponto-Caspian invasive species, on the 
patterns of dispersal, and on the impacts of the invasive species. This information is applied to areas of the Great 
Lakes and used to generate case studies on change due to invasion, the causes of invasion, and future predictions. 
The results show a mix of continuous and discontinuous dispersal. Hypothesized general attributes of invasive 
species are valuable to predict successful invaders but not for determining impacts. The authors recommend that 
additional research focus on benthic food webs to understand the primary impact of invaders. 
E-2 
