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- Title
Intraspecific competition in lake-dwelling triclads.
- Authors
Reynoldson, T. B.; Bellamy, L. S.
- Abstract
The population dynamics of Polycelis nigra, F. tenuis and Dugesia polychroa were studied in laboratory ecosystems provided with a constant supply of natural food and maintained under a temperature regime which followed that of an outdoor pond. The same phenomena, related to breeding, such as shrink-age of adults, mortality of small individuals and curtailment of egg production occurred in these populations as was observed earlier in field populations. Analysis of size-structure, population numbers and biomass suggested that the major changes were the result of intraspecific competition for food. Experiments to study the effect of varying the population density of triclads upon food up- take, under conditions of a constant food supply, showed that competition may occur although all the food is not utilised. This was attributed to the aggregation of triclads on individual prey. Certain anomalies in the performance of some of the populations were considered to be partly due to chance events in this feeding behaviour of triclads. It was shown that while exocrene substances influenced the fecundity of triclad populations this was a minor factor compared with intraspecific competition for food.
- Subjects
TRICLADIDA; POLYCELIS; DUGESIA; LAKES; BIOTIC communities; TURBELLARIA
- Publication
Oikos, 1971, Vol 22, Issue 3, p315
- ISSN
0030-1299
- Publication type
Article
- DOI
10.2307/3543855