60.5 Saturday, Jan. 5 Molecular analysis demonstrates that proximity is a poor indicator of food source for a photosynthetic herbivore. MIDDLEBROOKS, ML*; BELL, SS; CURTIS, NE; PIERCE, SK; Univ. of South Florida; Univ. of South Florida; Univ. of South Florida; Univ. of South Florida firstname.lastname@example.org
The diet of many herbivore species has been determined, often incorrectly, by their proximity to potential food plants. Many species of herbivorous, sacoglossan sea slugs, can acquire energy through photosynthesis by intracellular chloroplasts sequestered from their algal food. This additional source of energy might allow these slugs to inhabit areas devoid of food sources for as long as they are photosynthetically capable. We tested this hypothesis on Elysia clarki, a kleptoplastic sacoglossan endemic to the Florida Keys. Elysia clarki can maintain photosynthetic activity for 3 to 4 months without feeding and even synthesizes chlorophyll and other plastid related compounds to sustain the symbiotic chloroplasts. Using a combination of field surveys and DNA sequencing to identify the sequestered chloroplasts, we found that proximity to food sources was a very poor indicator of the diet of E. clarki. In fact, in some cases, slugs had been feeding on alga not detected in the field surveys. These findings support the idea that photosynthetic herbivores may be able to survive in areas lacking food sources for prolonged periods of time. (Supported by an anonymous patron).