The outcome of total sexual selection in the leaf-footed cactus bug

The capacity for sexual selection to produce astonishingly varied phenotypes has long captured the attention of biologists. Darwin was first to conceive of its two primary components: male-male competition and female choice. These forces are typically examined independently, despite acting together in nature. While these two components often favor similar traits in males, female preferences do not always align with competitive male traits, potentially leading to stabilizing, disruptive, or negligible net selection. Thus, explicit measures of total sexual selection are crucial to fully understand how sexual selection shapes phenotypes. Narnia femorata (Hemiptera: Coreidae), the leaf-footed cactus bug, is an excellent tool with which to measure total sexual selection. Male N. femorata compete using weaponized hind legs. Males with larger weapons have an advantage at excluding rivals from their cactus territories and mating opportunities, yet males with smaller weapons may bias paternity in their favor through sperm competition. Females often mate multiply and select territories to mate, feed, and lay eggs. Here, we estimated selection gradients for male-male competition and female mate choice, and we determined which best predicted paternity. Such explicit measures of sexual selection deepen our insights into the evolutionary dynamics of sexual selection to make more accurate predictions about the emergence of successful mating strategies.