The Effects of Size and Distance of Islands on Protozoan Colonization Patterns in a Laboratory Microecosystem
Huntly, Nancy J.
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Laboratory studies were conducted to investigate the dynamics of the colonization process of the Protozoa. Previous investigations of the process in natural eco systems have indicated a general conformity of protozoan communities to the MacArthur-Wilson species equilibrium model, the effects of island area, distance from an epi center, and epicenter community structure were examined. Polyurethane foam blocks were used as island substrates, fully colonized substrates from Douglas Lake, Cheyboygan County, Michigan being used as epicenters. No relationship between density of particular species in the epicenter communities and their presence in island systems as colonizing species was observed, nor did avail ability of additional habitats seem to alter the composition of the original epicenter community over the period of a given experiment. Distance greater than a certain maximum level lowered the immigration rate. Area effects may have been active. Community structure, the final number of species observed, and estimated immigration and extinction rates all indicated that equilibrium was not approached during the period of experimentation in any of the systems tested. Certain species of flagellate and cilate protozoans were recorded from the island communities in a number of the experimental situations and may be considered as colonizing species or resident colonists. These species have been previously recorded as colonists in experiments conducted in Douglas Lake, and their presence in the same role in the present, experiments, using an essentially current-free system, indicate that they are capable of at least some degree of active dispersal.