Data: Rapid evolution of an adaptive taste polymorphism disrupts courtship behavior

The evolution of adaptive behavior often requires changes in sensory
systems. However, rapid adaptive changes in sensory traits can adversely
affect other fitness-related behaviors. In the German cockroach, a
gustatory polymorphism, ‘glucose-aversion (GA)’, supports greater
survivorship under selection with glucose-containing insecticide baits and
promotes the evolution of behavioral resistance. Yet, sugars are prominent
components of the male’s nuptial gift and play an essential role in
courtship. Behavioral and chemical analyses revealed that the saliva of GA
females rapidly degrades nuptial gift sugars into glucose, and the
inversion of a tasty nuptial gift to an aversive stimulus often causes GA
females to reject courting males. Thus, the rapid emergence of an adaptive
change in the gustatory system supports foraging, but it interferes with
courtship. The trade-off between natural and sexual selection under
human-imposed selection can lead to directional selection on courtship
behavior that favors the GA genotype.