Name ______BIODIVERSITY - Using and interpreting the Shannon Index

The term biodiversity has meaning at a variety of levels – genetic, species, larger taxonomic groups, and community or ecosystem. Biodiversity has been defined by the US Office of Technology Assessment as “the variety and variability among living organisms and the ecological complexes in which they occur.”

Estimates of the number of species worldwide vary tremendously. Already identified and named are 1.6 – 1.8 million species of plants and animals. But many are not yet identified or named – some estimates are as high as 28 million unnamed species!! Biodiversity is declining worldwide – because of human activities, rates of species extinctions are higher than at any other time in the history of Earth.

Diversity is an ecological measurement of species evenness and richness. In other words – it measures how many different species are in an ecological system and how many of each species are represented. A common measure of species diversity is the Shannon Diversity Index (also called the Shannon-Weaver or the Shannon- Weiner index).

The index is: H' = -Sum of (pi * lnpi)

Where H' = Shannon Diversity Index

pi = ni/Ni = the proportion of the total # of individuals occurring in species

ni = number of individual species

Ni = The total number of all species

The most important source of error comes from failure to include all species from the community in a sample, but this error decreases as the proportion of species represented in the sample increases. Values of the Shannon index for real communities are often found to fall between 1.0 and 6.0.

Assignment: Part A:

In this lab you will calculate the S-W Index for the following data.

Species # of Organism pi lnpi pilnpi Whip mud worm 8 Mussels 20 Barnacles 15 White anemones 5 Dusky sea slug 2 Isopods 6

Show your calculations and describe the diversity of this community. Part B: Compare the diversity of the rice field to the Costa Rican wetland, Quebrada Mula.

Group Rice Field Quebrada Mula Nematodes 4 1 Annelids 2 11 Mollusks 4 34 Spiders 2 3 Insects 1 12 Larvae 11 7 Crustaceans 3 115 Total 27 183 Individuals

Rice Field

Species # of Organism pi lnpi pilnpi Nematodes Annelids Mollusks Spiders Insects Larvae Crustaceans Quebrada Mula

Species # of Organism pi lnpi pilnpi Nematodes Annelids Mollusks Spiders Insects Larvae Crustaceans Assess whether there are differences in species richness between the 2 different quadrants and possible reasons why.