Data from: The social factors driving settlement and relocation decisions in a solitary and aggregative spider

Both ecological and social factors play an important role in determining the structure of animal settlement patterns. While the ecological factors determining animal settlement are generally well known, the relative importance of social factors in mediating fine-scale settlement choices is poorly understood. As a result, we have little knowledge of why individuals choose to settle near specific neighbors. Here we used a web-building spider (Nephila plumipes) that settles both solitarily and next to neighbors within aggregations to examine the specific social factors that influence settlement decisions. Within experimental enclosures we observed the settlement patterns of females pre- and post-male release. This allowed us to compare two models of aggregative settlement in lekking species, the hotshot and preferences models, to examine the relative importance of a female’s phenotype and mate attraction to further dissect settlement and relocation decisions. We show that mate attraction increased with aggregation size, and that larger females were generally preferred, supporting both the hotshot and preference models of aggregative settlement. We further demonstrate that smaller females that attracted fewer males within an aggregation were most likely to relocate. Our results demonstrate how social feedback can affect initially state-dependent settlement decisions, thereby highlighting the dynamic nature of settlement

Data for subsampling analyses

Data for subsampling analyse

Subordinate Fish Mediate Aggressiveness Using Recent Contest Information

Memorizing dominance relationships can help animals avoid unwinnable subsequent contests. However, when competitive ability changes over time—for example, as a function of condition—it may be adaptive to “forget” these dominance relationships and for subordinates to once again enter contests with previously dominant individuals. Here, we examined the behavior of pairs of male cichlid fish, Julidochromis transcriptus, in repeated contests separated by different time intervals. We found that the time taken to reach resolution of dominance relationships influenced subsequent aggressive behavior of the subordinate toward the dominant, with longer initial contests leading to higher subsequent aggression. Longer time intervals between contests also increased aggression from the subordinate toward the dominant. These results are consistent with increasing uncertainty due to ambiguous contest outcomes and increasing time intervals. Our results also show that a longer time was necessary to resolve contests between larger pairs, suggesting a self-assessment strategy, but not a mutual assessment strategy. Taken together, larger individuals appear to adaptively lose or ignore previously gathered social information because they have a higher fighting ability and better body condition. Therefore, we conclude that losing or ignoring unreliable information may be an adaptive strategy in the context of dominance relationships.publishe

Kasumovic_Jordan_Analyses

Data for the main analyses of the pape

Order effects in transitive inference : does the presentation order of social information affect transitive inference in social animals?

Transitive inference (TI) is the ability to infer social relationships between individuals (e.g., if A < B and B < C, then A < C), and has been documented in a variety of vertebrates. Many studies of TI use the task of inferring social dominance, where a subject animal A first directly interacts with B (e.g., A subordinate to B: A < B), and then indirectly observes the interaction of B and an unknown C (B < C), using both direct and indirect information to infer its own relationship with C (i.e., A < C). However, order effects are known to influence learning, especially in complex scenarios, and we have little understanding of the effects of presentation order in transitive inference. Here we show that the cichlid Julidochromis transcriptus can use TI to correctly assess social relationships when information is presented in the order opposite to that most commonly employed in studies of TI. We find that focal individuals (A) can transitively infer their relationships with an unknown individual (C) when initially given indirect experience (i.e., eavesdropping that B < C) and then given direct experience (A < B). We conclude that J. transcriptus can infer social relationships when experiencing first indirect and then direct social information. We suggest that in this and many other species, transitive inference may occur in either presentation order, and future studies of TI should account for order effects of social information.publishe

The multivariate evolution of female body shape in an artificial digital ecosystem

Human bodies exemplify complex phenotypes, likely to be subject to complex evolutionary forces. Despite the importance of body shape to health, social interactions and self-esteem, our understanding of body evolution and integration remains simplistically focused on simple ratios like waist-hip ratio (WHR), and body mass index (BMI), or manipulations of one or a few traits. Evolutionary selection analyses give a multivariate perspective, but highly correlated body measures create multicollinearity problems. Here we develop an original approach mimicking Darwinian selection to study how clonal lines of bodies, allowed to vary in 24 attributes via a mutation-like process, evolve in a digital ecosystem over 8 generations. Ten of 24 traits changed by more than one |S.D.| over seven generations of selection. Analyses of selection within generations, change in population mean, and change within clonal family lines all implicate slenderness, particularly narrow waists and long legs as the most important dimension of body attractiveness. WHR did not offer any improvement on waist girth as a predictor of attractiveness. Within the most successful clonal lineages, selection favored greater shapeliness, including larger busts, in addition to slenderness. Our results reveal the complex, multivariate nature of attractiveness, and that the success of simple ratios like WHR and BMI in previous studies is probably incidental to the importance of waist girth and general slenderness. Our results also suggest that the integration of the entire body phenotype is at least as important as any one trait, and that more than one way exists to make an attractive body

The effects of familiarity and social hierarchy on group membership decisions in a social fish

Members of animal groups face a trade-off between the benefits of remaining with a familiar group and the potential benefits of dispersing into a new group. Here, we examined the group membership decisions of Neolamprologus pulcher, a group-living cichlid. We found that subordinate helpers showed a preference for joining familiar groups, but when choosing between two unfamiliar groups, helpers did not preferentially join groups that maximized their social rank. Rather, helpers preferred groups containing larger, more dominant individuals, despite receiving significantly more aggression within these groups, possibly owing to increased protection from predation in such groups. These results suggest a complex decision process in N. pulcher when choosing among groups, dependent not only on familiarity but also on the social and life-history consequences of joining new groups

The use of multiple sources of social information in contest behavior : testing the social cognitive abilities of a cichlid fish

Theory suggests that living in large social groups with dynamic social interactions often favors the evolution of enhanced cognitive abilities. Studies of how animals assess their own contest ability commonly focus on a single cognitive task, and little is known about the diversity or co-occurrence of cognitive abilities in social species. We examined how a highly social cichlid fish Julidochromis transcriptus uses four major cognitive abilities in contest situations; direct experience, winner/loser effects, social eavesdropping and transitive inference (TI). We conducted experiments in which fish assessed the social status of rivals after either direct physical contests or observed contests. Individuals used direct information from a previous physical encounter to re-establish dominance without additional contact, but winner/loser effects were not observed. Social eavesdropping alone was ruled out, but we found that transitive reasoning was used to infer social dominance of other individuals of unknown status. Our results suggest that in stable hierarchical social groups, estimations of contest ability, based on individual recognition pathways such as TI and direct experience, are more prevalent than social eavesdropping or winner/loser effects. We suggest that advanced cognitive abilities might be widespread among highly social fishes, but have previously gone undetected.publishe

Data from: The social and ecological costs of an ‘over-extended’ phenotype

Extended phenotypes offer a unique opportunity to experimentally manipulate and identify sources of selection acting on traits under natural conditions. The social cichlid fish Neolamprologus multifasciatus builds nests by digging up aquatic snail shells, creating an extended sexual phenotype that is highly amenable to experimental manipulation through addition of extra shells. Here, we find sources of both positive sexual selection and opposing natural selection acting on this trait; augmenting shell nests increases access to mates, but also increases social aggression and predation risk. Increasing the attractiveness of one male also changed social interactions throughout the social network and altered the entire community structure. Manipulated males produced and received more displays from neighbouring females, who also joined augmented male territories at higher rates than unmanipulated groups. However, males in more attractive territories received more aggression from neighbouring males, potentially as a form of social policing. We also detected a significant ecological cost of the ‘over-extended' phenotype; heterospecific predators usurped augmented nests at higher rates, using them as breeding sites and displacing residents. Using these natural experiments, we find that both social and ecological interactions generate clear sources of selection mediating the expression of an extended phenotype in the wild