Biodiversity indices...

Now this is a completely new concept for me. What's a biodiversity index? A diversity index is a mathematical measure of species diversity in a community. Diversity indices provide more information about community composition than simply the number of species; they also take the relative amount of different species into account. There are several biodiversity indexes:
Species richness is simply the number of species present in a sample, community, or taxonomic group. Species richness is one component of the concept of species diversity, which also includes the relative abundance of species. Species diversity is one component of the concept of biodiversity. Patterns of species richness can be observed at a variety of levels. The causes of these patterns remain active areas of research in ecology, biogeography, and evolutionary biology.
Simpson's Index measures the probability that two individuals randomly selected from a sample will belong to the same species (or some category other than species).

n = the total number of organisms of a particular species
N = the total number of organisms of all species
Shannon diversity index is another index that is commonly used to characterize species diversity in a community. Like Simpson's Index, Shannon's index accounts for both abundance and evenness of the species present.

where p_i is the fraction of individuals belonging to the i-th species.

I guess it's clear... It'd gonna take me some time to understand it completely, though. I hope we continue to work with this topic. :)