Meeting Abstract

P1.47  Monday, Jan. 4  Succession of dipterans in container communities: Is the IFC hypothesis supported in an animal community? MURRELL, E.G.*; JULIANO, S.A.; Illinois State University, Normal, IL egmurre@ilstu.edu

Many hypotheses for mechanisms of ecological succession focus on terrestrial plant communities, but could also potentially apply to animal communities. We used aquatic macroinvertebrate container communities (larval dipterans) as a model system to study succession because of their small size, simple community structure, and rapid species turnover. To determine if succession occurs in this system, we arranged 128 water-filled containers in groups of 4 in a forested area. One-fourth of the containers were destructively sampled each week, and the abundances of 6 dipteran taxa were counted per container. We also tested whether Egler’s initial floristic composition hypothesis – or for our study, initial faunistic composition (IFC) – could explain changes in community composition. We allowed one week for initial oviposition, then covered half of our containers and compared community composition of covered and uncovered containers for the remainder of the study. We used MANOVA and profile analysis to compare relative abundances of taxa across treatments (open vs. closed), week, and all relevant interactions. Relative abundances of taxa were significantly affected by week (p<0.0001) and by week*treatment interaction (p=0.0287), indicating that succession patterns differed for our two treatments. Diversity was lower in covered containers (p=0.0108), with 2 taxa present in only open containers. Thus, the data do not support the IFC hypothesis. We also tested the effects of changing abiotic conditions (temperature, volume, and dissolved sodium concentrations) on diversity and relative abundances of taxa. None of these covariates were significant. We describe our plans to further use container systems in order to test other succession hypotheses.