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Studying Living Organisms

The Evolution of Canis pedatus

Dawn J. Clawson
Woodrow Wilson Biology Institute
1995


Target age or
ability group:
High school biology, introductory and advanced.
Class time
required:
Two 50-minute class periods.
Materials and equipment: The student handout, paper and pen/pencil.
Summary of activity: The students, working in small groups, will examine the given characteristics of a previously unknown dog-like creature -- Canis pedatus -- and decide if the creatures would survive when relocated to a new environment, and then decide whether or not the animal population would change in any way over time to make them more suited, or adapted, to their new home.
Prior knowledge, concepts or vocabulary necessary to complete activity:
The students should know the principles of evolution via natural selection, and understand that these changes only occur if there are environmental pressures to favor the characteristics of one individual over the characteristics of another individual in that same environment. They also need to understand that structural changes in their bodies will result in new ways of functioning. The result of such selection is that some individuals will be favored to survive and reproduce, and thus pass on their characteristics to the next generation.

Teacher Instructions

Divide students into groups so that there are at least two groups working on each environmental region. Separate groups as much as possible. Have each group number off from one to four, so that each group has a number, which will represent one of four possible environments. Distribute the Student Handout to each student. Have students circle their group number under the Environment heading. This becomes the new habitat on which they are to focus for this activity.

The Evolution of Canis pedatus

Introduction: Four hundred years ago an international expedition discovered a previously unknown dog-like creature. The expedition's leaders, all from different regions of the world, each took several of the species on board their vessels and returned to their own lands. The animals were originally held in captivity and allowed to mate randomly. Their numbers increased to several dozen, when most of them were set free to roam. You are to decide if the animals could have survived in their new habitat and then, if they had survived, how the animals could have changed over four centuries as they adapted to their new environments.

Objectives: The purpose of this activity is to decide:

1. if a population of the species Canis pedatus would survive being relocated to a new environment;

2. if the species Canis pedatus would show adaptations to its new environment over a period of four hundred years;

3. whether the animals with those adaptations still belong to the species Canis pedatus.

Background information on the species Canis pedatus:

Height: medium, similar to a spaniel
Hair: medium length, brown, white, black mix
Tail: bushy, hangs down to its heelsSnout: long , similar to a collie, with medium-sized teeth
Ears: short and pointed
Feet: unusually large, with small sharp claws
Poor night vision
Moderate runner: runs at speed of the average house cat
Omnivorous, but has a particular liking for small birds

Environments:

1. Equatorial island, with dense vegetation, rains part of every day, hot and humid at all times, animal and bird life plentiful, but the animals are nocturnal.

2. Arctic Circle country, flat, ice and snow covered for six months each year, plant life is then hard to find, though there are still animals around.

3. Temperate, mountainous, days are warm and nights are cold year-round, areas of open grassland, water is plentiful, abundant animal and bird life.

4. Desert, but rocky terrain, days are hot and dry, nights can be cool, water can be hard to find, desert plants are common, and animal and bird life is scarce.

Instructions: You will be assigned to groups and each group will be given a number that corresponds to a new environment. As a group, decide if the species could have survived after being allowed to roam in the wild, given their characteristics and lifestyle. Explain your decision. Examine each trait and decide if it would have changed in any way to make the animal more suited to its new environment. Record every change that could have occurred, together with a statement to explain the functional benefit of the change. Complete the assignment with a written description of the animal and its lifestyle. Include a sketch that shows your "new and improved" appearance for this animal. Conclude by answering the following question: Is this modern animal still a Canis pedatus?

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