Epistasis underlying a fitness trait within a natural population of the pitcher-plant mosquito, Wyeomyia smithii

Abstract

We selected on divergent photoperiodic response in three separate lines from a natural population of the pitcher-plant mosquito, Wyeomyia smithii. Line crosses reveal that there exists within a population, diverse epistatic variation for a fitness trait that could contribute to adaptive potential following founder events or rapid climate change.

Figure 1.—

Critical photoperiod of long and short selected lines and their F₁ and F₂ hybrids and backcrosses (B₁, B₂). The plots show mean log₁₀(critical photoperiod, hr ± 2SE). The solid line shows the weighted least-squares expectation of an additive model. The results of the joint-scaling test (see also Table 1) are shown for the additive-dominance-maternal (ADM) and the ADME models; ***P < 0.001; ^NSP > 0.05. The symbols in the boxes refer to the sign of digenic epistasis (+, significant and positive; −, significant and negative; 0, not significant) in the order A × A, A × D, D × D from the coefficients in Table 2.