Quantitative genetics of the trade-off between fecundity and wing dimorphism in the cricket Allonemobius socius

Abstract

Considerable evidence indicates that in general there is a phenotypic trade-off between wing dimorphism (a threshold trait) and fecundity in insects. However, the demonstration of a genetic basis to this trade-off has been shown in only one species, Gryllus firmus. In this paper we present evidence for another species, the cricket Allonemobius socius. There were significant negative phenotypic correlations between wing morph and fecundity during the first two periods following eclosion (0-12 days and 13-16 days) and also cumulative fecundity (i.e. macropterous females laid fewer eggs than micropterous females). Macropterous and microp-terous females did not differ in fecundity during the remaining two periods (17-20 days and 21-24 days). Both wing morph and age-specific fecundities had significant heritabilities. There was a significant negative genetic correlation between wing morph and fecundity during the first 12 days after eclosion. The standard errors of the estimates for the remaining periods were too large to permit a meaningful conclusion. Analysis of family mean data indicated that fecundity did not vary in a dichotomous manner with wing morph but was best described as a continuous function of the underlying continuously distributed trait.