Biology Professor & Students Study Guppies in Trinidad

Dr. Douglas Fraser, professor of biology, and three of his students have been published in the May 2011 issue of Behavioral Ecology and Sociobiology. Christopher Brousseau ’07, Kristina Cohen ’06 and Summer Morse-Goetz ‘06, conducted research together with Dr. Fraser in Trinidad to answer the question, “Do guppies act as “chaperones” in facilitating the dispersal of the killifish?” Below Dr. Fraser provides a summary of the study and findings. To read the published journal article in Behavioral Ecology and Sociolgoiology, follow the link: http://www.springerlink.com/content/w2104m87768q2v81/
 
Guppies as heterospecific facilitators: a precursor of exploratory behavior?

The present study is part of a long term research project that studies the evolutionary ecology and behavior of tropical stream fish on the island of Trinidad. The popular aquarium guppy and another minnow-size species, the killifish, have been the principal focus of our studies. By marking and recapturing individuals in streams we have been able to document in detail the movement behavior of the killifish. We find that several predator fish, such as the wolf fish, pose severe threats to killifish, causing them to stay close to the margins of streams and generally hidden among rocks and woody debris. They never venture into open water. Yet, the killifish manage to disperse. Individuals move. We investigated one mechanism by which movement might be facilitated in the face of predation threat. We had previously observed that schools of guppies often contain immature killifish, roughly the same size as the guppies. This raised the possibility that guppies made the killifish “feel” bolder and more willing to take risks in moving through predator-threatened zones such as smooth sandy beaches that punctuate the edges of the streams. Killifish are afraid to cross such stretches that lack the protective cover of stones. Do guppies act as “chaperones” in facilitating the dispersal of the killifish? That is the specific question we set out to answer. Siena students Chris Brousseau ‘07, Kristina Cohen ‘06 and Summer Morse-Goetz ‘06, worked with me in Trinidad where we developed an aquarium method to test the killifish for their boldness when guppies were present and when they were absent. We found that when alone, individual killifish were rather shy and reluctant to venture out from a safe refuge in the aquarium.  When guppies were present in the tank, the killifish were significantly bolder (achieved a higher “boldness score”).  The students also seined the edges of streams where they caught guppies and killifish and where they documented and confirmed the co-occurrence of the two species. This research has broad significance for the field of behavioral ecology, because it links a specific behavioral phenomenon, association with an unrelated species, to a larger ecological pattern, dispersal in streams.