. The Canadian field-naturalist. 1981 SINGH: Polymorphism in Land Snails 195 colonies of 1979 but were found only in the B colony in 1952. The degree of fusion between two or more bands when all five bands are present, however, varies from colony to colony in 1979 as in 1952. The frequency of fused bands 3 and 4, when bands 1 and 2 are absent, was quite variable and ranged from 0% in colony 6 to 27% in colony 1. Others, like colonies 2, 3, and 5, had intermediate frequencies around 10%. A number of rare morphs that are lumped together as "others" varied from colony to colony and were
. The Canadian field-naturalist. 1981 SINGH: Polymorphism in Land Snails 195 colonies of 1979 but were found only in the B colony in 1952. The degree of fusion between two or more bands when all five bands are present, however, varies from colony to colony in 1979 as in 1952. The frequency of fused bands 3 and 4, when bands 1 and 2 are absent, was quite variable and ranged from 0% in colony 6 to 27% in colony 1. Others, like colonies 2, 3, and 5, had intermediate frequencies around 10%. A number of rare morphs that are lumped together as "others" varied from colony to colony and were represented by very few individuals in each sample. Judd (1955) postulated that the bandless pattern "would probably soon become prevalent when once established" owing to its dominant nature over the banded forms (Stelfox 1918); but the frequency of a given form is not dependent on whether it is dominant or recessive. Genetic dominance is totally uncon- nected with gene frequency, as shown by the Hardy- Weinberg equilibrium law. The frequency of a given morph or rate of its increase is dependent on its rela- tive Darwinian fitness in a Mendelian population (see Spiess 1977 for details). The similarity among seven 1979 plus two 1952 colonies for their banding pattern was evaluated by obtaining minimum spanning distance based on two main principal components (Figure 2). Although the two principal components account for only 58% of the variance, the relative position of different colonies in this network is comparable to the dendrogram (Figure 3) based on similarity indexes between pairs of colo- nies which utilized all the information. The CLUS- TAN IC computer program (Wishart 1975) was used for obtaining the patterns in both figures. Colony 4 of 1979 and B of 1952 are most similar for their band patterns. Furthermore all 1979 colonies are closer to the B colony as compared to the A colony of 1952, although the patterns that were specific to the A col- ony in 1952 are
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