Information flow through threespine stickleback networks without social transmission

Abstract

Social networks can result in directed social transmission of learned information, thus influencing how innovations spread through populations. Here we presented shoals of threespine sticklebacks (Gasterosteous aculeatus) with two identical foraging tasks and applied network-based diffusion analysis (NBDA) to determine whether the order in which individuals in a social group contacted and solved the tasks was affected by the group's network structure. We found strong evidence for a social effect on discovery of the foraging tasks with individuals tending to discover a task sooner when others in their group had previously done so, and with the spread of discovery of the foraging tasks influenced by groups' social networks. However, the same patterns of association did not reliably predict spread of solution to the tasks, suggesting that social interactions affected the time at which the tasks were discovered, but not the latency to its solution following discovery. The present analysis, one of the first applications of NBDA to a natural animal system, illustrates how NBDA can lead to insight into the mechanisms supporting behaviour acquisition that more conventional statistical approaches might miss. Importantly, we provide the first compelling evidence that the spread of novel behaviours can result from social learning in the absence of social transmission, a phenomenon that we refer to as an untransmitted social effect on learning.

Social dynamics, network structure, and information diffusion in fish shoals.

“…Social transmission refers to informed individuals increasing the probability of naive individuals becoming informed due to the former's behavior . In contrast, when information or a trait can only be acquired at a specific location-as in our study-individuals who frequently associate together might also be likely to acquire this information at similar times to one another through otherwise asocial means-that is, an untransmitted social effect (Atton et al, 2012;Webster et al, 2013). For example, individuals traveling together could simultaneously encounter a novel food patch.…”

“…Although this does not eliminate the possibility of social transmission, it does suggest that if a social transmission effect is present, it is no stronger than the more parsimonious explanation of information flow occurring primarily via untransmitted social effects (Atton et al, 2012). Conversely, if social effect strength was greater for the real patch relative to the control, this would point to a role for social transmission in addition to any untransmitted social effects at work.…”

“…Social transmission occurs when the behavior of informed individuals positively influences the rate at which naïve individuals acquire the trait . Conversely, untransmitted social effects can occur when individuals acquire the same information at similar times simply as a result of their tendency to be found in close spatiotemporal proximity (Atton et al, 2012;Webster et al, 2013); under such a scenario, whether or not an individual is informed is irrelevant to that individual's influence on the rate at which its associate acquires the trait. To avoid counting such simultaneous solves of the foraging task as instances of information transfer, information was not permitted to transmit between individuals that acquired the task solution within 10 seconds of one another; similar approaches have been used in foraging bird flocks (Aplin et al, 2012;Farine, Aplin, et al, 2015).…”

“…While still a new technique, NBDA has already been employed in both laboratory and field studies on a number of species, including: three-spined sticklebacks (Gasterosteus aculeatus) (Atton et al, 2012;Webster et al, 2013;Atton et al, 2014), multiple species of Paridae songbirds (Aplin et al, 2012;Aplin et al, 2015), ring-tailed lemurs (Lemur catta) , red-fronted lemurs (Eulemur rufifrons) (Schnoell & Fichtel, 2012), and humpback whales (Megaptera novaeangliae) (Allen et al, 2013). So far NBDA has been used primarily to study the spread of foraging information related to locating and accessing food, but it has the potential to address nearly any behaviorally transmitted trait-e.g., vocal traditions in cetaceans (Noad et al, 2000), mate-choice copying (Dugatkin, 1992), or defensive behaviors (Magurran & Higham, 1988;Mineka & Cook, 1988).…”

“…Social transmission refers to instances where the behavior of informed individuals facilitates information acquisition by naïve group members . In order to avoid counting simultaneous discovery of the task solution as instances of information transfer, I did not allow social transmission between individuals that solved the task within 10 seconds of one another (Atton et al, 2012;Farine, Aplin, et al, 2015).…”