Meeting Abstract
Trinidadian guppies (Poecilia reticulata) are found in the mountain streams of northern Trinidad, where they co-occur with a diversity of predators. However, the distribution of these predators is limited by large barrier waterfalls, leading to upstream populations experiencing significantly lower predation risk and allowing them to grow to large population sizes. High population density in upstream reaches has led to a diet shift in these populations to incorporate a larger amount of algae and detritus than in downstream populations, which primarily feed on small invertebrates. These two diets should require different feeding mechanisms: a “picking” motion for invertebrates and a “scraping” motion for attached algae and detritus. Previous studies have demonstrated significant morphological differences between the head and jaws of high and low predation guppies, but it remains unclear to what extent these differences are evolved or plastic and whether they lead to differences in performance. We bred wild-caught guppies from one high and one low predation locality in the Aripo River in northern Trinidad to an F2 generation in the lab. These fish were then raised on a gel food presented in one of two ways: as a slurry that required picking food particles from the water column and as a thin layer spread onto a tile that required a scraping feeding motion. Mature fish were then filmed while feeding on both food types and these videos were analyzed to measure kinematic variables such as gape width, gape angle, angle of approach, and duration of the feeding sequence as a proxy for feeding performance.
