Meeting Abstract

100.3  Saturday, Jan. 7  How do invasive species maintain dominance in nutrient limited environments? A comparison of behavioral and physiological mechanisms between an invasive and a native snail. HANSEN, B. K.*; KRIST, A. C.; MARTINEZ DEL RIO, C.; University of Wyoming; University of Wyoming; University of Wyoming

Resource competition can shape species composition. In environments where nutrients are limited in either quantity or quality, the organisms best equipped to exploit these resources may gain a competitive advantage. The New Zealand mudsnail (Potamopyrgus antipodarum), a world-wide invader that can dominate secondary productivity, may benefit from such an advantage. Potamopyrgus antipodarum is a parthenogenetic snail, with high growth rates, and a high percent of somatic phosphorus (P). Consequently, these snails should have a high demand for P. Because freshwater ecosystems are often limited in P, successful animals like P. antipodarum must be exceptionally efficient at acquiring P from their food, either through effective foraging or digestive efficiency. However, previous work suggests that P. antipodarum consumes less food per unit biomass than the native snail Fossaria sp. To determine whether P. antipodarum gain an advantage in P limited environments, we compared preference, feeding rate and gut retention time for food containing low and high P content for P. antipodarum and the native snail, Fossaria. Relative to food with high P content, we predicted that low P food would not be preferred, would be consumed at a higher rate (compensatory feeding) when diets were presented alone, and would be maintained in the gut for more time. Consistent with our prediction, P. antipodarum consumed low P food at a higher rate than high P food. In contrast, the native snail Fossaria consumed high P food at a higher rate. Ongoing experiments will reveal whether differences persist between the invasive and native snail when faced with diets differing in P.