Through studies on plankton, Allen et al. showed that manipulating this variable can cause exponentially higher rates of evolutionary change. A factor that corrects for this variable is added to the West–Brown–Enquist model in the metabolic theory of ecology. This variable affects aromatase accumulation to impact the outcome of a “sensitive” period in one class’s development. David Atkinson built on Bergmann’s rule to describe how organisms’ (*) size relates to this variable. (-5[1])This variable increases the number of niches in an ecosystem by increasing primary productivity. Sex determination in most reptiles is driven by (10[2])this variable, which decreases along with metabolic rate and activity during hibernation. For 10 points, name this variable, which organisms can regulate by sunning or resting in shade. ■END■ (10[1])