Figure 6.
Spatiotemporal dynamics of temperature in soil-like environments and their effect on the distribution of worms using fixed and plastic thermotaxis strategies. A, Simulated variation in temperature as a function of time of day and distance from the soil surface. Smooth lines were calculated from Equation 10 using Tave = 20°C, T1/2 = 15°C, and zd = 10 cm. Traces progress from dark blue (0 cm, surface) to light blue (35 cm) in 5 cm increments. B, Simulated heat map of the variation in temperature as a function of distance from the soil surface (ordinate) and time of day (abscissa). C, Constant isothermal tracking, positive and negative thermotaxis. Lines show the mean depth (relative to the soil surface) versus time of day of a simulated population of worms migrating either up or down the thermal gradient at all temperatures, or performing continuous isothermal tracking. D, Tc-dependent thermotaxis in wild-type (blue) and dgk-3 (green) worms. Mean depth versus time of day of a population of wild-type worms performing thermotaxis as measured in Figure 4. Shade indicates starting depth (same color scheme as in A). For all simulations, Tave = 20°C, T1/2 = 15°C, and zd = 10 cm. Simulated behavioral responses in C and D are superimposed on a color image of temperature variation. Deep blue is 0°C, and red is 40°C.