The Effects of Behavioral Interactions On the Feeding Habits of Amphipod Species

Abstract

Species that use the same area and resources present a paradox for understanding species coexistence. This is especially true for cryptic species because they are phenotypically similar. This study examines three cryptic amphipod species (Sp. A, B, and C) in the genus Hyalella and how competition affects food preferences. Feeding habits of amphipods may be altered by interactions with other amphipod species by exploitation (one species being better at finding and using resources) or interference (physically excluding competitors). Species B is a better competitor than species C which are better at avoiding predators. However, we do not know the mechanism by which species B outcompetes the other species. We hypothesized that species A and C will use high-quality algae patches when alone and that species B will displace species A and C. Species were placed together in arenas containing foraging patches varying in algal content. Our results showed that species A and C spent more time on low-quality patch with species B, but species B was not dependent on the presence of species A and C. This study gives greater insight into the role of interspecific competition in shaping resource use and patterns of coexistence in nature. This study gives greater insight into the role of interspecific competition in shaping resource use and patterns of coexistence in nature.