Different measures of this quantity are unified as a series of values that depend on an order parameter q called the Hill number. R. H. Whittaker introduced a set of terms that defines the beta form of this quantity as the ratio (10[1])between its local and regional forms, (10[1])which are respectively denoted alpha and gamma. Historical perturbations such as glaciation have been proposed to explain a phenomenon in which this quantity increases as latitude approaches zero. This quantity is measured by the Simpson (-5[1])index, (-5[1])which accounts for richness and (10[2])evenness. Human activity (10[1])threatens (10[1])regions with high values of this quantity known as its “hotspots,” which include the Amazon (10[1])rainforest. For 10 points, name this measure of how many different species reside in an area. (10[1])■END■ (10[1])