| Author Title Journal |
Reynoldson TB (1950) Natural population fluctuations of Urceolaria mitra (Protozoa, Peritricha) epizoic on flatworms. Jour Animal Ecol 19(2): 106-118 |
Abstract / Notes
Population data are based on weekly counts from Dec. 1946 to Dec. 1947 from a sample of twenty Polycelis tenuis from a small pond on the college grounds. Urceolaria mitra infested mainly Polycelis tenuis but was also found in small numbers and low incidence on P. nigra, and Dugesia (Planaria) lugubris. The infestation of D. lugubris was sporadic, occurring when the peritrich population was high. Seasonal fluctuations were small, this probably a result of epizoic habit. Positive, significant correlation between fluctuations in population and rainfall were found, but the reason for this is not yet known. There was no significant relationship with temp. There was some indication that during periods of increase in abundance the avg. size of individuals declined due to binary fission, but any correlation between abundance and size was masked by the highly significant negative correlation between temp. and avg. size. This was even more pronounced when the largest individual in each weekly sample was related to the temp., showing that it was an effect on adult size which was operating. There was wide variation in the urceolarian population of individual worms of equal size and no relation between the size of the worm and the epizoic population apart from 2 months when the peritrich popula-was at its peak. Recently hatched worms had a smaller population of U. mitra than older individuals.| Home page -- (Main hierarchy) |