The Rules of Assembly, according to benthic freshwater diatoms
Andrew Bramburger, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]
Paul Hamilton, Canadian Museum of Nature, [email protected]
G. Doug Haffner, Great Lakes Institute, Univ. of Windsor, [email protected]
Abstract
Historically, investigators working in different geographic regions have invoked a variety of often contradictory mechanisms, to explain the development and maintenance of biological communities. We used both experimental and observational approaches to examine the composition, structure, and dynamics of benthic diatom assemblages from freshwater lakes spanning ~70 degrees of latitude in an effort to reconcile deterministic and stochastic notions of community control within a single unified concept. Our results suggest that both spatial and temporal heterogeneity of habitat characteristics influence the degree of ecological specialization among taxa within a community, leading tropical assemblages to become more specialized than their high-latitude counterparts. Above a threshold of specialization, assemblages demonstrate evidence of habitat resource partitioning rather than competitive dynamics. Further, while all assemblages tend towards deterministic dynamics during periods of stability, specialist assemblages typical of tropical regions demonstrate evidence of determinism earlier in succession than temperate, generalist assemblages. Additionally, taxa within specialist communities are more likely to respond in an independent, as opposed to paired or interdependent, fashion when challenged with a disturbance resulting in altered environmental conditions. These findings suggest that ecological specialization of taxa within communities mediates community characteristics within the context of tradeoffs between spatial and temporal environmental heterogeneity.
1. Keyword
biodiversity
2. Keyword
diatoms
3. Keyword
benthic flora
4. Additional Keyword
community ecology