EFFECTS OF AGE, BODY-SIZE AND SITE ON REPRODUCTION IN THE SOUTHERN APPALACHIAN LAND SNAIL MESODON-NORMALIS (PILSBRY, 1900)

While high population densities negatively affect juvenile growth rate s, adult body size and reproductive output in many land snails, there is conflicting evidence on the importance of adult age on the body siz e-reproduction association. We explored experimentally the relationshi ps between adult age, adult body size, site of origin, and reproductiv e output components of single and paired adult snails over an annual c ycle in the southern Appalachian land snail Mesodon normalis. The numb er of clutches per 'older' adult snail was double that of 'younger' ad ults, and single snails had three times as many clutches as paired adu lts. Clutch size and hatching success were also dependent upon the sit e of origin of the experimental snails. However, the total numbers of eggs produced and hatching success of the eggs was independent of adul t shell diameter, the single-paired treatment levels, and the adult ag e and site of origin. While certain components of reproductive output in Mesodon normalis corresponded to those in European helicids, the pr esence of a strong age-reproductive association and the lack of a size -reproductive output dependency were surprising. These findings for Me sodon normalis suggest that different forces are affecting reproductio n in snails of differing ages, and that total egg production is not th e population size-body size link in the regulatory process in this woo dland species.