Summary
Populations of coexisting and of allopatrically occurring species of hydrobiid snails (Hydrobia ulvae, H. neglecta, H. ventrosa and Potamopyrgus jenkinsi) have been studied in 90 localities within three different areas. When H. ventrosa coexists with H. ulvae they show character displacement, i.e., the average body size of the former is smaller and that of the latter is larger. When these species live alone they are of approximately the same size. It is shown here that the size ratio between the coexisting species usually found (1.3–1.5) allows stable coexistence based on food praticles size selectivity alone. Variation in the degree of character displacement from locality to locality is explained by different degrees of genetical isolation of the populations. Coexisting H. ventrosa and H. ulvae have shorter, more well-defined periods of reproduction than they do when they occur alone. H. neglecta is larger than coexisting H. ventrosa and smaller than coexisting H. ulvae. Due to the patchy distribution and the fluctuating populations of this species, and due to the fact that pure H. neglecta populations are rare, data on this species are difficult to interpret. Potamopyrgus jenkinsi shows a different food particle size selection than the Hydrobia spp. of identical sizes. Competitive interactions between P. jenkinsi and coexisting Hydrobia spp. are therefore probably weak. In accordance with this, P. jenkinsi does not show character displacement when coexisting with, e.g., H. ventrosa.
The fact that the major study area, the Limfjord, is only 150 years old as a marine habitat as well as various more recent man-made changes of the coast line allow estimates of the time scale of the microevolutionary changes which lead to character displacement.
Similar content being viewed by others
References
Bondesen, P., Kaiser, E. W.: Hydrobia (Potamopyrgus) jenkinsi Smith in Denmark, illustrated by its ecology. Oikos 1, 252–281 (1949)
Brown, J., Wilson, E. O.: Character displacement. Syst. Zool. 5, 49–64 (1956)
Collin, J.: Om Limfjordens tidligere og nuv≸rende marine Fauna med s≸rligt Hensyn til Bløddyrfaunean, 168 pp. Copenhagen: Gyldendalske Boghandels Forlag 1987
Fenchel, T.: Factors determining the distribution patterns of mud snails (Hydrobiidae). Oecologia (Berl.) 20, 1–17 (1975)
Fenchel, T., Kofoed, L. H., Lappalainen, A.: Particle size selection of two deposit feeders: the amphipod Corophium volutator and the prosobranch Hydrobia ulvae. Mar. Biol. (in press, 1975)
Fish, J. D., Fish, S.: The breeding cycle and growth of Hydrobia ulvae in the Dovey Estuary. J. mar. biol. Ass. U.K. 54, 685–697 (1974)
Hespenheide, H. A.: Ecological inferences from morphological data. Ann. Rev. Ecol. Syst. 4, 213–229 (1973)
Hutchinson, G. E.: Homage to Santa Rosalia or why are there so many kinds of animals? Amer. Naturalist 93, 145–159 (1959)
Hylleberg, J., Fenchel, T.: The growth and lifecycle of mud snails (Hydrobiidae). In preparation
Levins, R.: Evolution in changing environments, 120 pp. Princeton: Princeton University Press 1968
MacArthur, R. H.: Geographical ecology, 269 pp. New York: Harper and Row 1972
May, R. M.: Stability and complexity in model ecosystems, 235 pp. Princeton: Princeton University Press 1973
Muus, B. J.: Some Danish Hydrobiidae with the description of a new species, Hydrobia neglecta. Proc. Malacol. Soc. Lond. 35, 131–138 (1963)
Muus, B. J.: The fauna of Danish estuaries and lagoons. Medd. Danm. Fisk. Havunders., N.S. 5 (1), 1–316 (1967)
Robertson, F. W., Reeve, E.: Studies in quantitative inheritance. I. The effects of selection of wing and thorax length in Drosophila melanogaster. J. Genet. 50, 414–448 (1952)
Schoener, T. W.: The evolution of bill size differences among sympatric congeneric species of birds. Evolution 19, 189–213 (1965)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Fenchel, T. Character displacement and coexistence in mud snails (Hydrobiidae). Oecologia 20, 19–32 (1975). https://doi.org/10.1007/BF00364319
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00364319