Genetic variation in the life-history traits of Epiphyas postvittana: population structure and local adaptation

The light brown apple moth, Epiphyas postvittana (Walker) shows high intras pecific variability in morphological, physiological, demographic and behavi oural characters. To gain insight into the extent of adaptation and evoluti onary changes in response to environmental heterogeneity in this species, q uantitative genetic analyses of life-history variation were conducted for t wo natural populations under two thermal conditions (23 degrees C and 28 de grees C). Paternal half-sib heritability and genetic correlation in six lif e-history traits (i.e. development time, adult body weight, adult lifespan, age at first reproduction, the number of eggs laid during the first 5 days after emergence, and total fecundity) were compared. Significant heritabil ities were shown consistently in development time; this is also true for ad ult body weight, except for the Canberra population at 23 degrees C. Howeve r, neither population differences nor the effect of temperature were statis tically detectable for any of these heritabilities, confirming thr generica lly determined flexibility. Positive genetic correlations between developme nt time and adult body weight, and negative genetic correlations between th e number of eggs laid during the first 5 days and adult lifespan were prese nt for these populations at both temperatures, indicating the presence of g enetic constraints. Pairwise comparisons of genetic correlations revealed t he heterogeneity of the mio populations and across temperatures. These resu lts suggest that the structure of generic covariance might have changed sig nificantly during the divergence of natural populations and in response to the alteration of environmental conditions in E. postvittana.