SIGNAL EFFICACY AND THE EVOLUTION OF MALE DIMORPHISM IN THE JUMPING SPIDER, MAEVIA-INCLEMENS

An extreme form of male dimorphism occurs in the jumping spider, Maevi a inclemens, where two male morphs differ dramatically in both morphol ogy and behavior. We examined the visual signals transmitted to female s by the two different morphs during courtship display. Even though th e display of each male is different, as a function of behavior and cou rtship distance, the males present females with images that are almost identical in height and visual target area. By substituting live male s with computer-animated sequences of male courtship behavior, the mal e morphs were superimposed upon each other, and females were determine d to have two distinct male-recognition templates. We hypothesize that the dimorphic males of this species evolved through sensory exploitat ion and selection for alternative male strategies that stimulate diffe rent fields of the female visual range.