IUCN / SSC Cat Specialist Group - Digital Cat Library |
|
||||||||||
|
||||||||||
|
|
| Berryman, A.A.; Gutierrez, A.P.; Arditi, R. | |
| Credible, parsimonious and useful predator-prey models - a reply to Abrams, Gleeson, and Sarnelle | |
| 1995 Ecology (76): 1980-1985 | |
We were asked to coordinate our response to criticisms by Abrams (1994), Gleeson (1994), and Sarnelle (1994) of our Special Feature on "ratio-dependent" predator-prey theory (Mattson and Berryman 1992). This has been no easy task, for the Special Feature contained a diversity of views and approaches to modeling predator-prey dynamics. For example, Berryman (1992) arrives at ratio-dependent predation through extension of the logistic equation, Arditi and Ginzburg (1989) through modification of the predator's functional response, and Gutierrez (1992) by combining the physiological process of energy allocation with random search for prey. Thus, although we may not use the same explicit form for the predator-prey equations, we agree on the underlying rationale, that changes in predator and prey numbers should be related to consumer/resource ratios. Our response is presented in two papers. In the first, Akcakaya et al. (1995) responded to criticism of their ratio-dependent functional response equation. This is because detailed and specific criticism has been directed, almost entirely, at the Arditi-Ginzburg (1989) model. For example, Gleeson (1994) objects to the assumption that predators "divide up" the prey before beginning to feed, and to prey becoming "infinitely available" as predators become infinitely rare, but these objections do not apply to the other models. In this paper we try to explain and clarify the differences and commonalities in our separate approaches, because our critics seem confused on this issue. We then respond to the criticism that ratio-dependent theory lacks a "plausible mechanism" (Abrams 1994, Murdoch 1994) by outlining the mechanism underlying ratio-dependent models. Next, we define the minimum set of biological attributes that credible predator-prey models should possess, and show that ratio-dependent models fulfill these requirements better than prey-dependent models of similar complexity, thereby countering Abrams' complaint that ratio models lack a "plausible justification". Finally, we maintain that ratio-dependent models have proven to be more useful for describing and explaining real situations and data. |
|
 |
PDF files are only accessible to Friends of the Cat Group. Joining Friends of the Cat Group gives you unlimited access and downloads in the Cat SG Library for one year, and allows you to receive our newsletter Cat News (2 regular issues per year plus special issues). More information how to join here |
(c) IUCN/SSC Cat Specialist Group ( IUCN - The World Conservation Union) |