Henricson, J. & L. Nyman. (1976). The Ecological and Genetical Segregation of Two Sympatric Species of Dwarfed Char (Salvelinus alpinus (L.) Species Complex). Reports of the Institute of Freshwater Research, Drottningholm. 55:15-37.
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Henricson, J. & L. Nyman
1976
The Ecological and Genetical Segregation of Two Sympatric Species of Dwarfed Char (Salvelinus alpinus (L.) Species Complex).
Reports of the Institute of Freshwater Research, Drottningholm
According to Nyman (1972) at least three sibling species of char within the so called Salvelinus alpinus (L.) complex can be distinguished in Scandinavia. Two of these are generally dwarfs with usually a littoral or benthic way of life, whereas the “normal” char is more pelagic. They also differ in their food habits, growth, spawning time etc. (Nilsson and Filipsson 1971). In certain lakes, where the isolating mechanisms have not been complete, hybridization has occurred and the gene flow has resulted in various stages of introgression.
Parasitological data can often contribute to an understanding of various biological problems in fish, for example population structure, feeding habits and phylogenetic problems (Kabata 1963, Margolis 1965). Makhovenko (1972) used parasites as indicators of different forms of char
from Kamchatka. In Sweden whitefish (Coregonus spp.), which constitute a complex of sibling species in various stages of introgression (Svärdson 1957), have been investigated for their cestodan parasites by Petersson (1971 a). Mayr (1970) states that parasites may aid in the discrimination of sibling species since “sibling species often differ in the number or the kind of parasites they carry”.
In connection with a parasitological investigation in a lake in southern Swedish Lapland it became evident that the char population could not be homogeneous. The present study has been undertaken 1/ to determine if more than one species of char inhabits the lake system and if so 2/ to determine which species are involved, 3/ to examine if the parasite faunas of two sibling species of char may contribute to the discrimination between them and 4/ to test what set of parameters would prove most suitable to assign individual fish to species.
One problem in the study of sibling species is to classify the individual specimen as belonging to one species or the other. This property is usually not directly measurable but evaluated using empirical measurements which are a priori known to be related in some way. All too often a single discriminating character cannot be found, and only a combination of measurements can provide the necessary information. When the number of parameters is large (> 3) and the objects numerous, one can use methods of numerical taxonomy (Sneath and Sokal 1973) also called methods of pattern recognition (Kowalski and Bender 1972). In the present study the chars were classified by a method based on modelling each separate class by a separate principal components model (Wold
