Biology
Biodiversity of Ground-Dwelling Arthropods
Name:
Date:
Points:
Introduction
Arthropods are the dominant life-form on Earth, representing about 63% of all species
(excluding bacteria, fungi, and algae). Beetles, alone, comprise 25% of all species. In this lab,
you will use pitfall traps to sample ground-dwelling arthropods (mostly insects and spiders) in
different habitats, classify the arthropods into morpho-species, and calculate the diversity of
beetles found in the different habitats.
Procedures
1. Read the Biodiversity Fact Sheet; alternately, use the following websites to obtain
background information:
 Ecological and Ecosystem Diversity, National Biological Information Infrastructure
 Biodiversity Fact Sheet, Ecological Society of America
2. Record your hypothesis on the data sheet.
3. Follow the procedures for setting up pitfall traps; each group will be responsible for placing
and collecting from 5 traps.
4. After 1-2 weeks, remove the contents of the pitfall traps and place into a 1-liter mason jar.
5. After washing the contents of the jars, sort the arthropods into morpho-species.
6. Record the data in the table.
7. Calculate abundance and diversity indices for each habitat; record the data in the table.
 See: Diversity Data Analysis
8. Construct a graph showing the effect of habitat on diversity.
 See: Constructing Bar and Line Graphs
9. Prepare a formal Lab Report
 See: Scientific Experiments and Publication Formats for Lab Reports
Hypothesis:
Response or Dependent Variable:
Independent Variable:
Sample size:
Table. Number of individuals collecting in pitfall traps in
various habitats.
Habitat
“Species”
Wheat field
Forest
Beetle species 1
Beetle species 1
Beetle species 1
Beetle species 1
Caterpillars
Spiders
Harvestman
Ground crickets
Total number
Number of species
H’
eH’
Questions
Which habitat had the most and least individuals?
Which habitat had the greatest and least species richness?
What is a morpho-species and why is it used instead of real species?
List 3 hypothesis to explain why abundance and diversity differs between habitats.
Is the data representative of the total diversity of the habitats? Why or why not?
What is the advantage and disadvantage of using species richness as an estimate of diversity?
Is there a relationship between diversity of a particular group (e.g., beetles), and the diversity of
the entire habitat?
What would happen if the diversity of arthropods was suddenly reduced by 50%? 95%?
Does this type of experiment have a control?