Animal personalities influence male mating behavior and reproductive fitness

The relationship between individual personality and sexual selection has the potential to provide insights into how variation in personality traits is maintained. However, whether and how individuals with different personality traits have different mating behaviors and the fitness consequences has remained largely unexplored. We tested the hypothesis that male individuals have different mating behavior depending on their personality traits, and that there are fitness effects of personality traits. To do so, we conducted trials to quantify personality traits and observed mating behavior under standardized conditions in the red flour beetle (Tribolium castaneum). We also collected the number of offspring produced by their female mates to assess the association between male personality and their reproductive fitness. We found that male beetles showed consistent inter-individual differences in walking distance, emergence time from shelter, and death-feigning time, which likely corresponding to 2 personality traits of activity and boldness. Although larger males had higher mating success and produced more offspring, some personality traits were also strongly related to mating behavior and reproductive fitness. Males with longer walking distances tended to seek female mates more promptly. Other than the morphological trait of body size, the emergence time from shelter (boldness) also showed a positive relationship with the number of matings and offspring reproduced. Furthermore, we found that the interaction between death-feigning time and walking distance in males influenced the number of matings they obtain, with either shy but active or bold but inactive males achieving more matings. We therefore highlight that alongside morphological traits, certain personality traits can also play a role in affecting mating behaviors and even reproductive fitness in males.