Fine, Distribution of Morph Frequencies in the Snail, Cepaea nemoralis Near Groningen

A possible case of genetic drift in colonies of the land snail Theba pisana

“…Wolda, 1969) and similar inheritance has been found in C. hortensis by Murray (1963). By analogy it is almost certain that the striping of T. pisana is also a hereditary feature, though no work has been reported on the genetics of this snail.…”

“…The importance of environment has been acknowledged by many authors who have either shown a direct relationship between environmental factors and morph frequencies (e.g. Arnold, 1969), or suggested that unidentified changes of environment reacting with the genotypes of the snails determine the morph frequencies which are constant over large areas (Cain and Currey, 1963), or change within small distances (Wolda, 1969). Goodhart (1963) has pointed out that" to prove that the Sewall Wright effect has been responsible for inter-colony variation, it must be shown that the effective breeding populations have been small enough for sampling errors to have been important, and that the observed variation is not due to differential environmental selection ".…”

On reduced size in spiders from marginal habitats

“…Studies on Curculionidae (Schauermann 1976), aphids (Way and Cammell 1971), Amphipoda (Enright 1976), parasitic worms (Holmes 1961(Holmes , 1962, freshwater snails (MooyVogclaer et al 1970), and land snails (Wolda 1969;Oosterhoff 1977) all reveal that denser populations have smaller individuals. It is important to note that no predators are present amongst these organisms.…”

Genetics of polymorphism in the land snail,Cepaea nemoralis

“…Large juvenile snails were collected in the Grijpskerk area (WOLDA, 1969a). The snails were kept in plastic boxes and fed on oats, milk powder and pieces of chalk.…”