Risk-Taking During Feeding: Between- and Within-Population Variation and Repeatability Across Contexts Among Wild Zebrafish.

Behavioral responses are shaped by a complex interplay of extrinsic factors, such as predation and flow conditions, and intrinsic properties such as metabolic state. We investigated variations in boldness among four populations of zebrafish collected from widely varying habitat conditions across India. We measured feeding latencies of fish in four contexts: in a novel environment; in an environment with refuge and predators; in the presence of a shoal; and in the presence of a shoal and predators. The population from a high-flow and high-predation habitat was significantly bolder than populations from low-predation and low-flow/stagnant habitats. Individuals were significantly bolder in the presence of shoal and predators than in the other contexts. In general, males were significantly bolder than females. Smaller individuals took greater risks to feed than larger individuals only within two populations. The high-predation, high-flow habitat fish also showed significantly lower between- and within-individual variation in boldness than all the low-predation and low-flow populations. Furthermore, we found significantly repeatable responses across contexts within all populations, indicating behavioral consistency. Differences in response to variations in experimental contexts and stress and individual differences in metabolic rates could possibly explain the observed between- and within-individual variation among populations.