P3.163 Friday, Jan. 6 The influence of male size and social context on activity, boldness, sociability and mating behaviors in the sailfin molly (Poecilia latipinna) LANGE, E.C.*; SEDA, J.B.; PTACEK, M.B.; Clemson Univ. email@example.com
Body size often influences behavior resulting in strong directional selection for increased size. In the sailfin molly, Poecilia latipinna, male size is genetically fixed and highly variable. Size influences alternative mating strategies; large males use courtship displays while small males utilize gonopodial thrusting. Intermediately-sized males are more flexible, switching between courting and thrusting depending on social context. We examined the influence of male size and social context on levels of activity, boldness, sociability and mating behaviors for P. latipinna from a single population. For each male, we measured activity in a social group, boldness in inspecting a fish predator, sociability with a conspecific group and mating behaviors in four social contexts (presence and size of competitor males). We found that male size was positively correlated with activity level (r2=0.113; p=0.045) and courtship display rate in all social contexts (r2=0.14-0.49; p<0.0001-0.044). Gonopodial thrust rates were negatively correlated with size only when the competitors were large (r2=0.19; p=0.017). There was no relationship between size and boldness or sociability. For courtship display rates, intermediate males showed an effect of social treatment on courtship display rates (F=3.507; p=0.026), but small and large males did not differ among different social contexts. In all male size classes, courtship display rates tended to increase when competitor males were the same or smaller in size and decrease when males competed with larger males. For thrust rates, males did not differ among social treatments. Future work on the genetic basis of male size and behaviors will determine the degree to which behavioral repertoires can evolve independently of size.