Natural Selection (Diana Griffin)
Title: Natural Selection on Furless Bunnies
Principle(s) Investigated: Inheritance and Changes in Allele Frequency
Standards:
Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.
Materials: Phone/computer with google classroom, bucket, 3 cups, 50 red and 50 white beads.
https://docs.google.com/spreadsheets/d/1lcPU8fdbVbJuqCq3ydouvp8TV8q6g0FjuXZDxhwhcqA/edit?usp=sharing
Procedure: Students will perform a simulation based on the frequency of genotypes in a population of bunnies.
Each group will receive 3 cups labeled with either homozygous recessive, homozygous dominant or heterozygous genotype (FF, Ff or ff).
The red beads represent the dominant allele F which give bunnies a normal fur coat. The white beads represent the recessive allele f which leads to furless bunnies in homozygous recessive individuals. The homozygous recessives do not survive long enough to reproduce.
The simulation will cover 10 generations. For each generation, a student will randomly pull two beads and record the genotype.
At the end of a generation, the homozygous dominant and heterozygous bunnies will be put back into the breeding population. The homozygous recessives bunnies will not.
After recording 10 generations, students will calculate the frequency (percentage of the population) of the alleles by dividing the number of each allele by the total population in that generation..
Student prior knowledge: Students are aware that some traits can be lethal and that will prevent genes from passing onto the next generation. Students are aware that only homozygous recessive genotypes will display the recessive phenotype.
Explanation: Each group will receive 3 cups labeled with either homozygous recessive, homozygous dominant or heterozygous genotype (FF, Ff or ff). The red beads represent the dominant allele F which give bunnies a normal fur coat. The white beads represent the recessive allele f which leads to furless bunnies in homozygous recessive individuals. The homozygous recessives do not survive long enough to reproduce. The simulation will cover 10 generations. For each generation, a student will randomly pull two beads and record the genotype. At the end of a generation, the homozygous dominant and heterozygous bunnies will be put back into the breeding population. The homozygous recessives bunnies will not. After recording 10 generations, students will calculate the frequency (percentage of the population) of the alleles by dividing the number of each allele by the total population in that generation.
Questions & Answers:
- How are the results of this simulation an example of evolution?
The simulation showed a trait that was lethal disappeared over several generations due to the inability to adapt to the environment. Natural Selection.
2. Did the number of dominant alleles change over 10 generations? why or why not?
The number of the dominant alleles did not change since no dominant alleles were being removed or added to the population. You start with 50 red beads and end with 50 red beads.
2. What would happen to the frequency of the recessive allele if the bunnies lived in a very hot environment?
The recessive allele would have an advantage in a hot environment and the dominant allele may be lethal in a hot enough environment. The frequency of the recessive allele would increase and the dominant allele would eventually disappear if the trait prevented bunnies from living long enough to reproduce.
Applications to Everyday Life:
Elephants in Africa are starting to be born without tusks. Having large tusks makes an elephant more likely to be shot by poachers for ivory and thus less likely to reproduce. Elephants without tusks have an advantage.
Antibiotic Resistant diseases are starting to proliferate specifically antibiotic resistant gonorrhea. Any strain of gonorrhea that is able to survive a human taking antibiotics has an advantage to survive and proliferate and spread.
Lactose Intolerance. As humans have evolved, certain geographic areas provide an opportunity for humans to drink cows milk. Humans living in these areas who also continued to make lactase past childhood had the advantage of an additional source of calories which would help them survive and reproduce more successfully than others that did not have lactase persistence. In humans who evolved these areas of the world, lactose intolerance is less common.
Photographs:
https://photos.google.com/share/AF1QipPznSwRVRgJcCR8eMEubeUOY9nJonfLxQSdiXTMearbzllBmP8VXSEDQbFmtjJb4g/photo/AF1QipNR7o9moJhXEALz8QeoLwaTadeJOb_lCBxe4Zcn?key=TXZqb0FnZGotTkJpX2FuWDBJYmtDNGJ5VERsVlRR
Videos: <iframe src="//cloud.swivl.com/i/2d0b073e7716c5d8fa599a36de0eb3a2" width="640" height="360" frameborder="0" scrolling="no" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>