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Social behaviors can be influenced by the genotypes of interacting individuals through indirect genetic effects (IGEs) and can also display developmental plasticity. We investigated how develop- mental IGEs, which describe the effects of a prior social partner’s geno- type on later behavior, can influence aggression in male Drosophila melanogaster. We predicted that developmental IGEs cannot be esti- mated by simply extending the effects of contextual IGEs over time and instead have their own unique effects on behavior. On day 1 of the ex- periment, we measured aggressive behavior in 15 genotypic pairings (n p 600 males). On day 2, each of the males was paired with a new opponent, and aggressive behavior was again measured. We found con- textual IGEs on day 1 of the experiment and developmental IGEs on day 2 of the experiment: the influence of the day 1 partner’s genotype on the focal individual’s day 2 behavior depended on the genotypic iden- tity of both the day 1 partner and the focal male. Importantly, the devel- opmental IGEs in our system produced fundamentally different dynam- ics than the contextual IGEs, as the presence of IGEs was altered over time. These findings represent some of the first empirical evidence dem- onstrating developmental IGEs, a first step toward incorporating de- velopmental IGEs into our understanding of behavioral evolution. 

Abstract It is well known that fishing is size‐selective, but harvest may also inadvertently target certain behavioral types or personalities. Changes in the abundance of behavioral types within a population have implications for fisheries management, including affecting catch rates, individual growth, and food web dynamics. Using streamside behavioral assays, we quantified the repeatability of behaviors in a population of Baikal grayling (Thymallus baicalensis) in northern Mongolia, a popular sport fish and important local predator. We assessed whether different angling techniques (i.e., fly or spinning gear) collected different behavioral types and whether variation in behavior was associated with body condition or diet (i.e., using stable isotope analysis). Surprisingly, we found no evidence for consistent individual differences in several behaviors within this population. Furthermore, differences in mean behaviors were not predicted by angling gear, body condition, or carbon and nitrogen isotopic signatures. We suggest that since this is a fished population, the range of behavioral variability in the population may have been reduced through previous behaviorally selective harvest. This might explain both the lack of difference in mean behaviors between fish caught by both gear types and the lack of evidence for consistent individual differences in behavior within the sampled population.