Multiple behavioral mechanisms shape development in a highly social cichlid fish.

Early-life social experiences shape adult phenotype, yet the underlying behavioral mechanisms remain poorly understood. We manipulated early-life social experience in the highly social African cichlid fish Astatotilapia burtoni to investigate the effects on behavior and stress axis function in juveniles. Juveniles experienced different numbers of social partners in stable pairs (1 partner), stable groups (6 fish; 5 partners), and socialized pairs (a novel fish was exchanged every 5 days; 5 partners). Treatments also differed in group size (groups vs. pairs) and stability (stable vs. socialized). We then measured individual behavior and water-borne cortisol to identify effects of early-life experience. We found treatment differences in behavior across all assays: open field exploration, social cue investigation, dominant behavior, and subordinate behavior. Treatment did not affect cortisol. Principal components (PC) analysis revealed robust co-variation of behavior across contexts, including with cortisol, to form behavioral syndromes sensitive to early-life social experience. PC1 (25.1 %) differed by social partner number: juveniles with more partners (groups and socialized pairs) were more exploratory during the social cue investigation, spent less time in the territory, and were more interactive as dominants. PC5 (8.5 %) differed by stability: socialized pairs were more dominant, spent less time in and around the territory, were more socially investigative, and had lower cortisol than stable groups or pairs. Observations of the home tanks provided insights into the social experiences that may underlie these effects. These results contribute to our understanding of how early-life social experiences are accrued and exert strong, lasting effects on phenotype.

Open Dislocation of the Scaphoid With an Associated Hamate Fracture and Fourth Metacarpal Fracture.

Scaphoid dislocation represents a rare injury with only a few case reports and limited case series reported in the literature. The majority of scaphoid dislocations result from a high-energy trauma causing hyperextension and ulnar deviation of the wrist. The severity of a scaphoid dislocation depends on the degree of periscaphoid ligamentous injury as well as the presence of concomitant injuries, such as axial carpal dissociation. The most common complication after a scaphoid dislocation is scapholunate dissociation, which emphasizes the importance of scapholunate ligament repair/reconstruction in these cases. We report a case of an open scaphoid dislocation with the associated injuries of a hamate fracture and fourth metacarpal fracture treated with an open reduction of the scaphoid, open ligamentous repair and augmentation of the involved carpal ligaments, and open reduction internal fixation of both the hamate and the fourth metacarpal fractures.