Promoting diversity: the relative importance of food web assembly.
Longmuir, Allyson*,1, Shurin, Jon1, 1 University of British Columbia, Vancouver, BC, Canada
ABSTRACT- Biotic and abiotic processes may both be important for mediating species coexistence and regulating diversity. Facilitation between trophic levels through food web assembly may promote positive correlations in diversity among producers and consumers. In addition, producer and decomposer diversity may be related due to variable biochemical composition of autotroph tissues and the abilities of different microbes to recycle them. However, the relative contributions of trophic interactions versus local environmental factors in promoting species coexistence are poorly understood. In addition, most studies of food web assembly have only considered two trophic levels. Here we examine correlations in diversity among zooplankton, phytoplankton and bacteria in the pelagic zone of 31 lakes in British Columbia. We sampled species diversity of zooplankton and phytoplankton through morphological identification while bacterial diversity was estimated through 16s rDNA derived DGGE bands. We examined correlations in diversity among zooplankton, phytoplankton and bacteria and their relationship with measured abiotic variables (nutrient supply and water chemistry). Correlations in diversity that are independent of physical factors may suggest a role for food web assembly in promoting diversity, while correlations with similar abiotic variables indicate shared responses to the environment. The strength of these relationships has implications for the role of abiotic processes versus food web interactions as factors regulating diversity across trophic levels.
Key words: phytoplankton, zooplankton, pelagic bacteria, biodiversity
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