Fig 1. Differentiation (Q _ST ±SE) between northern and southern populations for different quantitative traits [the dotted line represents F _ST (±SE) between the two populations based on allelic variation in microsatellite loci; *, Q _ST significantly higher than F _ST; DT1-DT4, the developmental time of 1^st to 4^th instar nymphs; DT5, the total developmental time of nymphs; Q _ST, the index of quantitative variation based on life-history traits; F _ST, the index of molecular variation derived from microsatellite markers].