Individual preference functions exist without overall preference in a tropical jumping spider

Female mate choice is a widespread and well-recognized phenomenon. Nevertheless, individual variation in female preference has not yet received the same attention, although such preferences can have important effects on evolutionary dynamics. Here we assess and compare population- and individual-level female preferences for male ornaments and size in the tropical jumping spider Hasarius adansoni in two sets of laboratory experiments. First, we paired females with a single male and quantified receptive behaviours (e.g. receptive posture, number of copulations) and unreceptive behaviours (e.g. attacking the male, running away from a male). We assessed whether these male traits were related to offspring quality and quantity to determine whether there was selection on female preferences. Then, we paired different females with three different-sized males, one per day, and scored similar behaviours to measure preference functions (relationship between male traits and female receptivity). Generally, the population of females did not show a consistent average preference for male traits, despite our finding that females mated to larger males produced more offspring. However, at the individual level, females showed different preference functions for male size, such that some females preferred larger males, while others preferred smaller males. We discuss these data in terms of the causes and consequences of individual preference functions, highlighting the importance of including individual preference functions in future studies that focus on sexual selection and how individual preference can maintain phenotypic variation in wild populations.