The Ontogenesis of the Pea Aphid Acyrthosiphon pisum

Phenotypic plasticity is an adaptive response to environmental cues (DeWitt and Scheiner 2004, Ghalambor et al. 2007, Simpson et al. 2011). An extreme example is phenotypic polyphenism, in which two or more discrete phenotypes can arise from the same genotype (West-Eberhard 1989, 2003, Hall 1999, Nijhout 1999, 2003, Ogawa and Miura 2014). The main phenotypic differences are manifested in morphs and developmental processes, but also in physiology, biochemistry and behavior. All these parameters in turn infl uence ecology and fi tness (West-Eberhard 1989, Whitman and Ananthakrishnan 2009, Simon et al. 2011a). In some cases, behavioral patterns rather than environmental signals generate phenotypic plasticity. Such patterns have probably evolved as an immediate response and therefore may infl uence morphology (Eberhard 1980, 1982, Bernays 1986; reviewed by West-Eberhard 1989).