COS 42-10
Effects of diversity on community assembly dynamics in newly formed ponds
Community structure is a result of the interaction between colonization history (priority effects) and on-going local and regional processes. Theory suggests that the initial level of genetic or species diversity in a new habitat will influence local processes and thus affect community assembly dynamics. Genetically diverse populations are predicted to be more likely to adapt to the local environment, monopolize resources, and buffer against invading competitors. Time of arrival can determine the outcome of competitive interactions and by manipulating time to arrival through stocking new habitats with the same subset of regional species, dispersal limitation and priority effects can be reduced. Dispersal promotes gene flow and provides the genetic basis on which selection can operate, however, basic processes such as quantifying dispersal rates in many organisms have yet to be fully studied. Empirical investigations simultaneously addressing the effects of stocking diversity and dispersal remain rare, especially for animal systems. To this end, we conducted a field experiment in which initial stocking genetic and species diversity of freshwater zooplankton in newly constructed pools was manipulated in a 2x2 fully factorial design. Community composition was monitored for 3 years and estimates of overland dispersal were measured.
Results/Conclusions
Despite theoretical predictions, after 3 years we found no difference in taxonomic richness or diversity among treatments or control ponds. Ponds followed similar colonization curves with most species accumulating during the spring and summer months. A total of 31 species were recorded in the metacommunity with an average cumulative taxonomic richness ranging from 6.1 to 7.6 species per pool. Dispersal of zooplankton taxa occurred rapidly but uniformly across the experimental landscape. We found 9 taxa dispersing in 7 days, and no difference in the number of dispersing propagules based on number of neighboring source ponds. Our study demonstrates that although genetic diversity of a focal population and initial species diversity have predicted effects on community assembly dynamics, they do not appear to have an effect on early successional community species richness and diversity in our planktonic metacommunity. At this stage of succession, our experimental pond communities are likely determined extensive abiotic filtering with little effects of biotic intra- or inter- species interactions.