IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Kolli, P. | |
| Predincting the density of predators to their prey: An investigation and extension of a mechanistic model | |
| 2004 Full Book | |
Predator-prey dynamics are extremely important in the field of ecology because their interactions help determine how a particular community establishes itself. Ecologists like to determine the density of organisms to their resources so that they can understand how a particular community is structured. However, due to many factors in the environment, a functional relationship between organisms and resources is very difficult to predict. Nichols et al developed a mechanistic model to shed some light on this question by investigating whether there is a functional relationship between two interacting species. The model predicts the density of tigers to ungulates (generalized to describe all prey in the environment) based on field techniques and experimental data in major cities of India. While the model serves to be a good predictor of tigers to prey in discrete time, there is not enough information to generalize the question of how to predict the density of organisms to their resources. This paper extends the model developed by Nichols et al to include information about the population dynamics of predators and prey in continuous time. The utilization of a well-known Lotka-Volterra system conveyed information about when the populations of predators and prey tend to stabilize and when they tend to oscillate. When the population dynamics tend to stabilize, it may be easier for ecologists to gather and make functional relationships about the densities of predators to their prey. However, if the populations of predators and prey oscillate, predicting the densities of predators to prey is difficult. After examination of the system, the results showed evidence that the carrying capacity (maximum number of organisms that an environment can sustain) of the environment dictated when the populations oscillate and when they stabilize. Furthermore, to investigate population dynamics in continuous time more accurately, this paper examines how prey modify their behavior in the presence of predators (in order to avoid predation, often called 'trait modification behavior'). Although the results of this investigation are not included in this paper due to time/space constraints, the system of three dimensional equations (a modified Lotka-Volterra system) that incorporate trait modification behavior is presented in detail. While the investigation in this paper provides a good start to model a functional relationship of predators to prey, there are many more factors that have to be accounted for in order to develop a functional relationship between organisms and resources of a particular environment. |
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