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 (-5[1])introduced a set of terms that defines the beta form of this quantity as the ratio between its local and regional forms, 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 (-5[1])by the Simpson index, (10[1])which accounts (10[1])for richness and evenness. (10[1])Human activity (10[2])threatens regions (10[1])with high values (10[1])of this quantity known as its “hotspots,” which include the Amazon rainforest. For 10 points, name this measure of how many different species reside in an area. ■END■ (10[2])