Figure 1.

Variation in components of avoidance behavior among wild isolates of C. elegans in response to thermal pulse. (A) The thermal avoidance assay and response. An infrared laser with a beam width larger than the worm body heats the surrounding area of the animal. The typical responses constitute a reversal (red), an omega turn (green), and forward movement (blue). (B) Profiles of behavioral metrics of 89 wild isolates of C. elegans in response to ∆T ∼ 0.4°. Each behavioral feature is Z-score normalized (See Materials and Methods). TMIN, time to reach pause state; SS, speed at start of the thermal pulse; DEC, deceleration to the pause state; MRD, mean reversal duration; pFR, probability of responding by reversal; pRO, probability of responding by omega; MRS, mean reversal speed; ACCN, acceleration; W, number of body bends during reversals; MaxS, Peak speed after exposure to thermal pulse. In the heat maps, the strains are reordered by the dendrograms resulting from hierarchical clustering. The Bristol strain (N2) and the Hawaiian strain (CB4856) are depicted by arrows and are colored orange and blue, respectively. For simplicity we show only 10 behavioral components. The other 56 behavioral metrics from the centroid speed profiles are not shown.