Beakman's World

Introduction:

When a resource in an organism's niche is limited, the organism must often compete in order to survive. This competition could be intraspecific if it is confined to members of the same species or interspecific if it exists between members of different species. Sometimes interspecific competition leads to competitive exclusion, which is the idea when resources are limited; one species will drive the less efficient one to local extinction.  Character displacement or avoiding competition by changing resource needs may lead to a subdivision of niches and survival of different species.

As Charles Darwin surveyed the plants and animals along the coast of South America, one of the most significant places he visited were the Galapagos Islands.  This cluster of volcanic islands lies 600 miles off of the coast of Ecuador, and certain islands contain populations of animals that are isolated from other members of their species on other islands.  Darwin was particularly struck by the fact that there were distinct variations in the physical characteristics of animals within a species that lived on different islands.  His observations in this area are considered to have been fundamental to his development of his theories about Natural Selection and the Origin of Species. 

The diversity among South American Finches was one of the most striking examples of variation within a species in the Galapagos Islands.  These birds are very similar to a species found on the mainland.  The continental birds eat seeds and have large bills that are adapted to crushing hard seeds.   The island finches are presumed to have descended from a common ancestor that accidentally was blown off course during a migration.  The beaks of the different finches on the islands are presumed to be adaptations that allow the birds to exploit different food sources.  They now range from the massive seed-crushing bill to a very slender bill in an insect-eating species.

Other birds also serve as fascinating examples of the fairly obvious ways different organisms have evolved through the development of specialized adaptations and the process of natural selection.  Birds are found almost everywhere in the world and this is evidence of their tremendous ability to adapt to a wide variety of environments.  All birds have feathers and their forelimbs are modified to form wings that allow most species to fly.  Birds walk on hind limbs that show tremendous variation depending on the substrate of the environment, their use for capturing prey, or modification for swimming.  Distinct shapes and sizes of the beak (as pictured below) correspond to the particular source of a bird's food, such as nectar, seeds, fruit, insects, fish, meat, flowers, etc.

National Standards Addressed:

Reproduction and Heredity is a standard that fits under the category life science.  It works by showing how heredity relies on reproduction.  It shows how traits can be passed from the parents to the offspring.  This is the link that ties together both reproduction and heredity.

The standard Diversity and Adaptations of Organisms is under the concept of life science.  This also works because it is dealing the genetics diversity of organisms and the passing on of traits.  These very diverse organisms can often pass on the same types of traits and have offspring that are very similar.  This in turn decreases the overall diversity of a particular group of organisms.

Under Unifying Concepts and Processes the standard Form and Function is addressed by this lab.  This is accomplished by having students think about the relationship between the form of the various bird beaks and the functions they perform.  You can explain to the students the various types of beaks and the types of foods those birds eat.   

Inquiry and Constructivism is a teaching standard that allows the students to think of their own ideas, questions, and experiments that they could run using this lesson as a guide.

Objectives and Benchmarks:

This activity allows students to observe how physical adaptations influence an organism's ability to compete for a limited resource.  Students will be able to create a simulated adaptation of an organism. 

Materials:

Toothpicks                Small paper cups            Implements      Forceps            Poster board     Pennies             Corn Soybeans        Gravel                              Paperclips        Clock                Ceramic Discs

Advanced Preparation:

Get materials for the activity.  Inform students about Charles Darwin and the Galapagos Islands

Procedure:

Have students scatter their toothpicks on the table.  They will each have a paper cup that will represent their mouth.  They will each be .bamboo-beak. birds. These birds collect toothpick food by using two bamboo skewers in chopstick fashion. Students need to place each toothpick in their cup before securing another.  Their goal is to gather as many toothpicks as possible in the allotted time. They need at least 12 toothpicks to survive. If they do not gather 12 toothpicks, they will not store enough food for winter and will die!  Have students calculate what % of the birds at their table survived and return the toothpicks to the table.

Tell the students that four of the bamboo-beak birds have become .finger-beak. birds.  They collect toothpick food using the 4th finger and pinkie on one hand.  Again, have each bird gather as many toothpicks as possible in the allotted time. Students should calculate what percent of the bamboo-beaks gathered at least the 12 toothpicks necessary to survive.  Also, how many of the finger-beaks survived.  They should return the toothpicks to the table.

Now, two of the finger-beak birds have become .forceps-beak. birds.  They collect toothpick food with forceps.  All three types of birds will compete to gather toothpicks.  The instructors will again regulate the time students have for collection.  Again students can calculate what percent of each type of bird survived and scatter the toothpicks evenly across the poster board.

This time each of the bird-beak types limits its toothpick search to the indicated section of the poster board that is provided. They then compete to gather toothpicks.  What percent of each type of bird survived?

Have each group choose a different type of food, either pennies, ceramic tiles, corn, soybeans, gravel, or paper clips and repeat these tests.  Ask students .did another beak become a better adaptation for obtaining food?.  Switch food sources and try them again.

From the collection of different instruments on the tray, have each student in the group choose a device to represent a different beak.  You will tell them what food source they get after they make their selections.  Students can see whose beak does the best job on that food in the time allowed.

The Grand Beak-Off:

Have two members represent each group in a competition with the other lab groups in the class.  Each group should choose a beak that is different from that chosen by any other group.  They will not know what the food is before they choose their beak.

Things to Consider:

How do the different feeding mechanisms in this activity resemble the actual adaptations birds have in the wild?

Given the trials, which mechanism resembles a successful feeding adaptation?

If this were a natural environment, which type of bird would benefit from the process of natural selection?

Possible Integration:

This lesson primarily focuses on life sciences but other disciplines can be integrated in.  History can be integrated in by teaching about Darwin and what he saw on his journeys to the Galapagos Islands.  Ecology can be integrated in to show how different environments can cause organisms to evolve in a certain way.

Critical Concepts: