ENGESZER, RE*; ALBERICI DA BARBIANO, L; RYAN, MJ; PARICHY, DM; University of Washington, University of Texas at Austin; University of Texas at Austin; University of Washington ; University of Texas at Austin: An analysis of shoaling preference in the zebrafish, Danio rerio

How social aggregations arise and persist is central to our understanding of evolution, ecology, behavior and psychology. When social groups arise within a species, evolutionary divergence and speciation can result. To understand this diversifying role of social behavior, we must examine the internal and external influences that lead to nonrandom assortment of phenotypes. Many fishes form aggregations called shoals that reduce predation risk while enhancing foraging and reproductive success. Thus, shoaling is adaptive, and signals that maintain shoals are likely to evolve under selection. Given the diversity of pigment patterns among Danio fishes, visual signals might be especially important in mediating social behaviors in the group. Our understanding of pigment pattern development in the zebrafish D. rerio allows integrative analyses of how molecular variation leads to morphological variation among individuals and how morphological variation influences social interactions. Previous work elucidated the role of early environment in determining social preference in the zebrafish. Here, we examine the time during which shoaling behavior and preferences arise. Furthermore, we assess the salient elements of the visual signal for shoaling, using multiple pigment pattern mutants and closely related species. This work provides a foundation for examining the proximate mechanisms involved in shoaling, and more generally, the genetic and environmental factors contributing to social behaviors in this biomedically important model organism.