PARENT SESSION
Poster Session # 1: Ecological Theory and Evolutionary Ecology.
Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
The Interaction of invasion sequence with a productivity gradient in assembled protist communities.
Zimmermann, Craig*,1, 1 Warnell School of Forest Resources, Athens, GA
ABSTRACT- Laboratory microcosm experiments in community assembly have shown that permutating the order of species invasion can significantly impact subsequent community structure. To date, the influence of varying environmental regimes on the effects of colonization history, however, has received only limited attention. Here, I explore the interaction of invasion sequence with a productivity gradient by assembling multitrophic detritus-based protist communities in a laboratory setting. Ordered species introductions were carried out under two alternative schedules against a productivity gradient consisting of five discrete nutrient levels. Censusing of community composition was performed at periodic intervals for a total of 64 days. In addition, a suite of chemical variables was quantified for each microcosm at the conclusion of the experiment to assess the impact of invasion sequence on media properties. The following results were observed: 1) the degree of overall variation in final community structure exhibited across productivity levels was dependent on invasion order, 2) alternative community states resulting as a function of invasion sequence were only observed at the three highest productivity levels, 3) a total of five unique community states was found to arise from the interaction of invasion sequence and productivity level, 4) the degree of variation in community composition en route to the final state was dependent on invasion order with the greatest variation in both sequences observed at the highest productivity levels, 5) invasion sequences were found to produce unique changes to media chemistry.
Key words: sequence effects, community assembly, alternative community states, invasions