Stabilising selection in Weldon’s snails: A reappraisal

Abstract

This paper reconsiders Weldon’s (1901, 1904) and Di Cesnoia’s (1907) oft-quoted research on stabilising selection on shell shape of terrestrial snails. Although I recognise problems in the experimental design, the commonest criticism is probably inapplicable. The statistical analyses were flawed, but a crude reanalysis supports Di Cesnoia’s conclusions, whilst Weldon’s results are also suggestive. It is argued that the technique is feasible but a positive result difficult to interpret. © 1990 The Genetical Society of Great Britain.