Authors: Jun Yang Humphrey G Smith Thomas N Sherratt David M Wilkinson
Publish Date: 2009/12/04
Volume: 59, Issue: 4, Pages: 635-645
Abstract
A longstanding debate in microbial ecology is the extent to which freeliving microorganisms exhibit cosmopolitan distributions We use a comparison of testate amoebae communities in cold “polar” locations Arctic Antarctic and Tibet to investigate how a microorganism’s size affects its probability of having a cosmopolitan distribution We show that the probability a given taxa being reported in all three locations increases as testate size decreases Likewise excluding those testates found only in Tibet very small testates 20 μm are more likely to occur in both the Arctic and Antarctic than in either of these poles alone Attempting to correct for phylogeny reduces the number of statistically significant relationships—both because of decreased sample size and potentially real phylogenetic patterns although some sizedependent effects were still apparent In particular taxa found in both the Arctic and Antarctic poles were significantly smaller than congeneric taxa found only in Tibet This pattern may in part be due to habitat effects with the Tibetan samples being more likely to have come from aquatic sites which may be more suitable for larger taxa Overall our analysis suggests that at least within testate amoebae a cosmopolitan distribution becomes increasingly common as median taxon size decreasesWe thank Edward Mitchell and our referees for comments The manuscript was completed while DW was on a sabbatical visit to WSL and EPFL in Switzerland—he thanks both organizations for their hospitality JY was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences No KZCX2YWQ0204 and KZCX2YWQN401 the Key Science and Technology Project of Fujian Province China No 2009Y0044 the China International Science and Technology Cooperation Program No 2009DFB90120 and the National Natural Science Foundation of China No 30800097
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