Collaborative Research with Miami University: Shifts in Wolf Spider Reproductive Behavior under Predation Risk
Ann L. Rypstra, Miami University, Hamilton Campus
Matthew H. Persons, Susquehanna University
Project Overview
At every moment, organisms must weigh trade-offs and make decisions about how to allocate time and energy into foraging and reproduction while trying to minimize its exposure to risks such as predation. The wolf spider, Pardosa milvina, displays effective anti-predator behavior (freezing, vertical movement, slowed movement, avoidance) in the presence of information regarding the presence of one of its major predators in natural systems: the co-occurring wolf spider, Hogna helluo. Pardosa milvina's anti-predator behavior appears to be mediated primarily through indirect cues (putatively silk draglines and excreta) that the predator deposits as it occupies an area. Previous studies have demonstrated that Pardosa shows graded levels of antipredator response based on the information content of these cues and the associated risk of predation. For example, Pardosa distinguishes between silk and excreta from a predator that has been feeding on them from one that has not. They also grade their defensive behavior based on if the silk and excreta come from a small predator or large predator, a male or a female as well as fresh cues compared to older cues. Using these cues as a surrogate for predation risk, we can experimentally decouple the fitness costs and benefits associated with performing reproductive or anti-predator behavior. Through manipulation of the presence or absence of H. helluo cues (perceived predation risk) with or without a living H. helluo (actual predation risk), the behavioral trade-offs and relative risk of predation can be quantified for every stage in the reproductive process. In each stage one can quantify: (1) the susceptibility of the animal to predation, (2) the behavioral changes made in response to a perceived threat of predation (3) the degree to which those behavioral changes confer some protection from predation and (4) the impact of altering reproductive behaviors in response to the threat of predation on reproductive success (egg production and phenology). Experiments will be conducted in the laboratory and in the field. This study will advance our understanding of predator-prey interactions and lead to a clearer understanding of how natural selection through predation interacts with sexual selection in shaping mating strategies at each stage of the mating process.
This research project began in September of 2002 and will continue over the next four years. We will add more information as time goes on.
Undergraduate Collaborators
Faculty, Post-doc, and Graduate Student Collaborators
Undergraduate Collaborators 