Figure 1. Overview of experimental design and interpretation. (A) Schematic shows Aripo and Quare river drainages in the Northern Range Mountains of Trinidad. We sampled population pairs from these two drainages, which represent distinct evolutionary lineages. (B) Wild-caught fish from each high- and low-predation population pair were reared to the second generation in the lab to control for maternal and environmental effects. At birth, second generation siblings from each population were split into rearing environments with (pred+) and without (pred-) predation cues. (C) This rearing design allows us to discern lineage effects (contrast between drainages), genetic divergence (contrast between different populations in the same environment), phenotypic plasticity (contrast between genetically similar fish in different rearing condition), and their interactions.