I have a layer of polygons and a layer of points. Points with common x,y coordinates are "stacked" upon each other, and they have an attribute called "species" which I am interested in. Every different species has a unique identifier. Several points may lie within a single polygon. I would like to know the diversity of species within each polygon (I believe accomplished via a variety statistic - each species has a unique identifier). Does anyone know how to do this? I know that I can use a "point statistic" to determine the diversity for a single (x,y), but I want the diversity assigned to the polygon based on all of the points intersecting with it.