Mate preference for a phenotypically plastic trait is learned, and may facilitate preference-phenotype matching

Fixed, genetically determined, mate preferences for species whose adult phenotype varies with rearing environment may be maladaptive, as the phenotype that is most fit in the parental environment may be absent in the offspring environment. Mate preference in species with polyphenisms (environmentally dependent alternative phenotypes) should therefore either not focus on polyphenic traits, be polyphenic themselves, or learned each generation. Here we test these alternative hypotheses by first describing a female-limited seasonal polyphenism in a sexually dimorphic trait in the butterfly Bicyclus anynana, dorsal hindwing spot number (DHSN), and then testing whether male and female mate preferences for this trait exist, and whether they are seasonally polyphenic, or learned. Neither naïve males nor naive females in either seasonal form exhibited mating preferences for DHSN. However, males, but not females, noticed DHSN variation and learned mate preferences for DHSN. These results suggest ...