The role of male coloration and ornamentation in potential alternative mating strategies of the dimorphic jumping spider, Maevia inclemens

Abstract

Abstract: Polymorphism can arise across taxa due to various selection pressures and potentially lead to alternative mating or antipredator strategies. For male jumping spiders, sexual selection and predation risk are often intertwined when courting cannibalistic females and may be a driving factor in the polymorphism of the jumping spider, Maevia inclemens. The dimorphic males of M. inclemens differ dramatically in their complex courtship behavior and display traits that may function as alternative mating strategies to reduce female aggression and maximize mating success. We hypothesized that males of the “tufted” morph honestly communicate condition or body size to females with three conspicuous tufts of setae on their head and males of the “striped” morph reduce female aggression with coloration commonly found in aposematic animals (here, yellow-orange pedipalps and striped legs). We examined correlations between tuft length and symmetry and metrics of body size and condition in field-collected spiders and conducted prey color choice tests (with live color-manipulated prey) to determine if yellow-orange and striped prey are avoided. Tuft length was variable and correlated with male size (but not condition). All prey color types were attacked at equal rates, but spiders oriented to striped prey more often, suggesting that male stripes may attract female attention without increasing predation. This study provides insight into the potential functions of the different courtship and visual displays of M. inclemens males. Using jumping spiders to study polymorphism can provide new insight into how multiple morphs can evolve, as males use mating strategies not only to impress females but also avoid getting eaten by their potential mates. Significance statement: Understanding the selection pressures that shape and maintain polymorphisms in natural populations is an active area of inquiry, yet most of what we know comes from a small handful of well-studied vertebrate taxa. The unique biology of jumping spiders and the fact that males have to avoid cannibalism during courtship, makes them well-suited to provide novel insights into the functions and maintenance of dimorphic male traits. The unusual male dimorphism of M. inclemens captured the attention of naturalists as early as the 1800s, yet we still do not understand why the two male morphs differ so dramatically in morphology and courtship behavior. Here, we propose and test a novel hypothesis that provides insight into the long-studied but still largely unexplained phenomenon of male dimorphism in this species.