Personality variation in a marine snail and heterogeneous selection in natural populations

Animal personality variation is characterized by among-individual differences in behavior that are consistent across ecological contexts and over time. However, processes influencing the amount of personality variation are not well understood. In this study, we tested 1 hypothesized mechanism through which variation in personalities may be maintained: spatial variation in natural selection. Through laboratory behavioral assays, we demonstrated that 2 personality traits—exploration and risk taking—are moderately repeatable for wavy turban snails, Megastraea undosa (mean repeatability values = 0.320 and 0.297, respectively). We also found that there could be up to a 1.7-fold difference in among-individual variation in behavior for different populations. We next measured natural selection on these behavioral traits by experimentally transporting assayed snails to field populations in a mark-recapture study to examine the relationships between behavioral traits and growth and survival. We studied 4 populations: 2 that had an abundance of slow-moving predators (whelks, sea stars) and 2 where slow-moving predators were absent and the major predators were fast-moving species (lobsters). Selection on behavioral traits varied significantly among local populations. Depending on location, patterns of selection could be predominantly stabilizing, disruptive, or correlational. Fitness surfaces were not necessarily similar for local populations with similar predator communities, and nearby locations could have strikingly different patterns of selection. Behavioral tendencies that were associated with high fitness in 1 population could be neutral or associated with low fitness in a nearby population. Such effects likely contribute to maintaining variation in animal personality within the broader population.