Challenge  What role does VARIATION play in natural selection? Useful Vocabulary:  Mutation  Speciation Activity 96: Battling Beaks

 Fossils  Observations  Simulations/models that explore predictions What evidence do scientists have for natural selection?

 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.

 Different types of beaks were probably created by random DNA mutations.  Do you know what a mutation is?? Why are there different beaks on the birds?

 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?

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. Procedure:

{ Rules for Rolling Dice Your TossForkbird Offspring 11- Tined 22- tined 44-tined 3, 5, 6Same as parent forkbird

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

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. Analysis Answers:

2.Initially, the only type of forkbird in the population was the 2-tined bird. Within one generation, though, both 1- and 4- tined 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 4- tined 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.