Above 20 C, even the high temperature one performs poorly, and rainbow trout suffer heat stress. Example 2 . A boreal moss from Finland has a PS max at 15 C, while a desert shrub has PS max at 44 C. PS depends on enzymes, and these plants have different forms of similar enzymes. Cutting of Atriplex lentiformis grown at different temperatures in growth chambers have different optimal PS temperatures. Those grown in cool chambers have a PS max at a lower temp than shrubs grown in a warm growth chamber.
Most species have a narrow range of optimal temperatures.
Endotherms regulate body temperatures by relying mainly on metabolic heat. They are a special kind of endotherm. Temperature Regulation by Ectothermic animals Animals can move, which gives them more options than plants, but the principals are the same. Many reptiles can maintain a nearly constant temperature that is very different from the air of the surrounding macroclimate by their behavior. Even insects can keep their temperatures elevated far above ambient temperature and within a narrow range by behavioral and physical mechanisms.