Environmental Stress and Biodiversity

Diversity Indices

Diversity is composed of / \ richness eveness (# of taxa) (distrib. of indiv. among taxa)

Note: richness alone often useful but problems: - does not take # of individuals into account

- very dependent on sample size unless large

Sequential Comparison Index

• Developed for use in 3rd world countries• Main advantage – no taxonomic

expertise required• Measures probability of next sampled

organism being the same as the last one• Will go over how to calculate in lab

Diversity exampleCommunity 1 Community 2

(evenness high) (evenness low)

Taxa ni pi pi2 ni pi pi2

A 10 0.1 0.01 91 0.91 0.8

B 10 0.1 0.01 1 0.1 .0001

C “ “ “ “ “ “

D “ “ “ “ “ “

E “ “ “ “ “ “

F “ “ “ “ “ “

G “ “ “ “ “ “

H “ “ “ “ “ “

I “ “ “ “ “ “

J “ “ “ “ “ “