What can we learn about past environments from evidence left by woodrats?

Author: Ricky Greer and Jan Snyder, Ed.D

Area: Life Sciences

Grade Level: 9-12

Overview: Note: This lesson requires the use of student-available computers that are connected to the Internet.

Through the use of resources on the Internet, students view typical woodrats and their nests in a normal habitat. Students are also provided opportunity to see woodrat (pack rat) middens and see examples of some that are thousands of years old. Evidence of changes in environment over the time span of these middens is analyzed such that they able to determine that areas that currently make up desert biomes were once less dry and more characteristic of forested regions.


Life Science: Content Standard C:

•Interdependence of Organisms

•Living organisms have capacity to produce populations of infinite size, but environments and resources are finite.

•The Behavior of Organisms

•Organisms have behavioral responses to internal changes and to external stimuli. Responses to externalstimuli can result from interactions with the organism’s own species and others, as well as environmental changes; these responses either can be innate or learned. The broad patterns of behavior exhibited by animals have evolved to ensure reproductive success. Animals often live in unpredictable environments, and sotheir behavior must be flexible enough to deal with uncertainty and change. Plants also respond to stimuli.

Arizona State Standards:

Strand 4: Life Science

Concept 3: Interdependence of Organisms

PO1. Identify the relationships among organisms within populations, communities, ecosystems, and biomes.

PO 2. Describe how organisms are influenced by a particular combination of biotic (living) and abiotic (non-living) factors in an environment

Concept 4: Biological Evolution

PO 1. Identify the following components of natural selection which can lead to speciation:

• potential for a species to increase its numbers

• genetic variability and inheritance of offspring due to mutation and recombination of genes

• finite supply of resources required for life

• selection by the environment of those offspring better able to survive and produce offspring

PO 4 Predict how a change in an environmental factor (e.g., rainfall, habitat loss, non-native species) can Affect the number and diversity of species in an ecosystem

Keywords: Woodrats,Middens, Evironmental Change, Fossil Record

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Lesson Plan (pdf/ doc)