The influence of metacommunity size on species diversity scaling in protist communities

Background/Question/Methods

I used protist communities to examine how the number of patches in a metacommunity, or metacommunity size, can affect the scaling of species diversity.  I expected that metacommunity size would alter species diversity scaling by affecting immigration and extinction dynamics within communities.  Metacommunities were established from a regional pool of protist species collected at Washington University’s Tyson Research Center (Missouri, USA).  I created 4 metacommunity treatments with 4 replicates each.  Control and small metacommunities consisted of 4 patches, or communities, large metacommunities were comprised of 12 patches, and habitat destruction metacommunities were initially established with 12 patches but later reduced to only 4 patches.  Small, large, and habitat destruction metacommunities were connected through bi-weekly dispersal events in which 4% of each patch was removed, mixed together, and dispersed equally back into all of the patches of a metacommunity.  Control patches were not connected by dispersal and were used to monitor temporal community dynamics in the absence of dispersal.  Metacommunities were sampled every 2 weeks over a 10-week period to quantify within community immigration and extinction dynamics. 

Results/Conclusions

I found that metacommunity size did not affect species diversity within a local community or at the regional scale of four dishes. However, metacommunity size did affect species composition. Small metacommunities varied more between replicates in their species composition than large metacommunities. Future analyses will identify if differences in species composition can be attributed to changes in community immigration and extinction dynamics.