Shelford's Law of Tolerance Victor Shelford(1911)extended this to animals Each ecological factor to which an organism responds has maximum and minimum limiting effects between which lies a range that it can tolerate. zone of i zone ofi cptimum zone of zone of intolerance stress zone stress intolerance sjenpIAlpu!jo Jeqwnu 1 low high environmental factor Figure 3.1 Shelford's law of tolerance.A plot of the number of individuals of a species as a function of some environmental factor(such as temperature)produces a bell-shaped curve that can be divided into various tolerance zones. Shelford Shelford’s Law of Tolerance of Tolerance Victor Shelford Shelford (1911) extended this to animals (1911) extended this to animals Each ecological factor to which an organism responds has maximum and minimum limiting effects between which lies a range that it can minimum limiting effects between which lies a range that it can tolerate. tolerate