1. Some groups contain more species than others
Species are not evenly distributed among taxonomic groups
Insects predominate over all other life-forms
40% of all insects are beetles
Groups accumulate species by
Adaptive radiation
Allopatric speciation
Low rates of extinction

2. Insects outnumber all other species

3. Measuring biodiversity is not easy
Out of the estimated million species on Earth, only million species have been successfully catalogued
Very difficult to identify species
Many remote spots on Earth remain unexplored
Small organisms are easily overlooked
Many species look identical until thoroughly examined
Entomologist Terry Erwin found 163 beetle species specialized on one tree species

4. Species Richness
Based solely on the number of species found in a given area
species richness (# species within the community)
R = s
where
s = the number of species

5. Shannon-Weiner Diversity Index
Combines two quantifiable measures:
species richness (# species within the community)
species equitability (how even are the numbers of individual species)
Calculated using the equation
H = - Pi(lnPi)
where Pi is the proportion of each species in the sample
and is equal to
ni/N
where
ni = the number of individuals in a given species i
N = the total number of individuals collected