MATERNAL ADJUSTMENT OF EGG SIZE ORGANIZES ALTERNATIVE ESCAPE BEHAVIORS, PROMOTING ADAPTIVE PHENOTYPIC INTEGRATION

Abstract

Numerous integrated traits contribute to any aspect of organismal performance, but favorable trait combinations are difficult to maintain in the face of genetic recombination. We investigated the role of maternal effects in promoting integration of alternative reproductive strategies (throat colors) with antipredator traits (escape behaviors and dorsal patterns) in the side-blotched lizard (Uta stansburiana). Previously, we reported that maternally derived estradiol adaptively pairs dorsal patterns with progeny throat colors. Here we show adaptive maternal effects on escape behaviors within each throat color morph. Specifically, yellow-throated females and all females mated to yellow-throated sires lay larger eggs. Larger eggs produce stockier offspring, who remain stockier throughout life. Stockiness promotes evasive escape behaviors (e.g., reversals), which are adaptive in barred, yellow-throated offspring. Orange-throated females lay smaller eggs, producing leaner hatchlings who perform vertical escape behaviors (e.g., jumping). Vertical behaviors enhance survival in striped, orange-throated progeny. Escape behavior was not heritable, but was organized by natural or experimental egg size variation. Maternal effects on adaptive phenotypic integration are likely common in polymorphic species, because recombination otherwise breaks apart beneficial trait combinations. Furthermore, our results provide insight into the role of body shape in organizing (and constraining) evolution of integrated reproductive and antipredator strategies.