Download Activity 96: Battling Beaks

Activity 96: Battling Beaks
Challenge What role does
VARIATION play in natural selection?
Useful Vocabulary:
 Mutation
 Speciation
What evidence do scientists
have for natural selection?
Fossils
 Observations
 Simulations/models that
explore predictions


You are going to do a simulation today, using
forks and cereal to represent birds feeding.

There is variation within the forkbird
population:
1-tined, 2-tined, and 3-tined birds (forks)

These represent the three different types of beaks
that forkbirds can have, yet all members of
forkbirds are in the SAME species.
Why are there different
beaks on the birds?

Different types of beaks were
probably created by random DNA
mutations.

Do you know what a mutation is??

Mutation: Any change in an organisms DNA

Are totally random

Occur during DNA replication

Can be helpful or harmful; Depends on
particular environment
Do you think that all of the forkbirds
will be equally successful at gathering
food?
Why or Why not?
Procedure:
Description of the Simulation:

The Forkbird Model:
Read the Pink Box on page F-34 to yourself.

Forkbirds eat “Wild Loops”

Original Forkbirds have 2-tined beaks.

Genetic mutations are shown with 1 or 4 tined
beaks.
Your Toss
Forkbird Offspring
1
1- Tined
2
2- tined
4
4-tined
3, 5, 6
Same as parent forkbird
{ Rules for Rolling Dice
What Should I be doing?
1.
Graph your class data on graph
paper. See set up on the board.
2.
Answer Analysis Questions 1-5 and
7 in your notebooks. PAGES 35-36
Analysis Answers:
1.
The 4-tined forkbird was the most successful.
Once it appeared in the population, it never
disappeared.
Instead, its numbers continued to increase.
This is because it was the best at gathering food
since it could scoop more food than the other
types of forkbirds.
2. Initially, the only type of forkbird in the
population was the 2-tined bird.
Within one generation, though, both 1- and 4tined forkbirds appeared. Over many
generations the 4-tined birds survived and
reproduced the most.
The 2-tined forkbird went from being the only
type of bird to just barely surviving.
The 1-tined forkbird appeared in the population
but was about as successful as the 2-tined
forkbird. Its numbers remained low.
2b. Once it appeared in the population, the 4-tined
forkbird was clearly the most successful.
The high rate of mutations, while allowing 4-tined
forkbirds to appear and take over quickly, also
contributed to the survival of 1- and 2-tined forkbirds.
If instead almost all of the 4-tined forkbirds had 4tined offspring, the future forkbird population would
likely be composed of 4-tined forkbirds.
3. Initially, the population had only one type of forkbird. Because of
genetic mutations, other types of forkbirds emerged over the
generations.
The genetic mutations introduced variation into the population. These
different birds competed.
The birds that were better at gathering food tended to survive and
reproduce.
In most cases, the surviving forkbirds passed their traits to their
offspring, which then had the same number of tines as the parent.
Over generations, the relative numbers of types of forkbirds in the
population changed.
The 4-tined birds were most successful at gathering food and became
the most common in the population.
Therefore, the 4-tined trait could be called an adaptation to this
environment.
5. This activity modeled DARWIN’S THEORY OF
EVOLUTION because the forkbirds did not change – they
were the same as the parent unless there was a mutation
The change in the population was first due to mutations and
then natural selection.
The birds that ate most efficiently survived and were able to
reproduce. This increased the type of bird that was most
efficient.