Anole Lizard Allele Frequency

Introduction: On the island of Stankonia, in the Caribbean Sea, there are two major lizard species. There are the smaller anoles and the larger curly-tailed lizards, which eat the anoles. You will be modeling the effect of various factors on the anole population such as predation and environmental factors.

Standard(s):

·  BI.7 a. Students know why natural selection acts on the phenotype rather than the genotype of an organism.

·  BI. 8. a. Students know how natural selection determines the differential survival of groups of organisms.

·  BI8. c. Students know the effects of genetic drift on the diversity of organisms in a population

Objectives: SWBAT…

·  Explain how natural selection determines the differential survival of groups of organisms.

·  Analyze multiple sources of evidence for evolution.

·  Explain how a great diversity of species increase the chance that at least some organisms will survive major changes in the environment

·  Analyze fossil evidence with regard to biological diversity, episodic speciation, and mass extinction.

Key:

·  Large green paper clips=large anoles (BB)

·  Large blue paper clips=large anoles (Bb)

·  Small paper clips =small anoles (bb)

Problem: Is this population evolving?

Procedure:

1.)  Obtain 10 large paper clips (5 blue and 5 green) and 10 small paper clips.

2.)  The large anoles have the genotype BB or Bb. The small anoles have the genotype bb.

3.)  Place the paper clips on your table and mix them up.

4.)  In generation 1 three small anoles (small paper clips) are eaten by curly tails. Move these small paper clips into your cup.

5.)  Fill in the Generation 1 row by first counting the number of anoles left over after the curly tail lizards ate the three small anoles.

6.)  Write in the genotype frequencies for this generation by examining the anoles left over after the predation. (BB=green paper clips, Bb=blue paper clips, bb=small paper clips)

7.)  Calculate the allele frequencies for Generation 1 by using the formula below and record the information in table.

Frequency of Allele B= Total # of B/ (divided by)total number of alleles in the gene pool

Frequency of Allele b= Total # of b/ (divided by)total number of alleles in the gene pool

8.)  Place the 20 anoles back onto the table. In Generation 2, a hurricane strikes the island. Randomly remove any ten anoles from the table.

9.)  Using the leftover anoles fill in the Generation 2 row in Table 1.

10.) Place the 20 anoles back onto the table. In Generation 3, the curly-tailed lizards are killed off by a virus, and none of the anoles are eaten. Using this information fill in the Generation 3 row in Table 1.

Table 1. Effect of Various Factors on Allele Frequencies of Anoles

Population Stage / # of Anoles / Genotype Frequencies / Allele Frequencies
Generation 1 / BB= Bb= bb= / B= b=
Generation 2 / BB= Bb= bb= / B= b=
Generation 3 / BB= Bb= bb= / B= b=

Analysis Questions:

·  Answer the questions below in complete sentences.

·  You may use the resources below to help this.

Resources:

·  http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_37

·  http://evolution.berkeley.edu/evolibrary/article/evo_39

Questions:

1.) Which environmental factors caused the largest change in the allele

frequencies?

2.) How can various environmental factors affect the allele frequencies of a species?

3.) How can changing an allele frequency of a species cause evolution?