The basic format starts with the class broken into three groups, or phenotypes, which we record the number of before we begin. They are the "stumpy" (genotype AA) who pick up their cork "food" with their wrists,
and "pinchers" (aa) who pick up their food with their thumb and index fingers.
We go outside, make a big circle, and I spread ~100 corks on the ground and say "go!"
They have to run and get as much food as possible using their feeding style. A colleague tried my lab this year a made a modification that I loved and tried with my class myself. Each student was given a container to serve as their "nest" or "den" that they had to bring their food back to.
Once all food is exhausted, I tell them how many corks they needed to survive. Usually I choose enough to kill off about 1/3 to 1/2 of the population. They return the corks to me, the dead individuals leave the population, and the winners are told to find a mate to reproduce with that will give them offspring most likely to survive. Typically this means everyone wants to mate with a pincher primarily, and a knuckle secondarily. Stumpys don't usually get much love.
Earlier in the year we do a "coin sex" lab where we explore probabilities of offspring inheriting alleles from various different genotypes of parents. I build on this experience with the Hunger Games Lab. A student who is a stumpy (AA) will label a coin with tape "A" on each side. A knuckler would have "A" on one side and "a" on the other. And a pincher would be "a" on both sides. Each side of the coin represents each homologous chromosome with the gene of interest. When students pair up with their mate, they both flip their coin. This simulate meiosis and Mendel's laws of segregation and independent assortment. The resulting allele face up is the one passed on in their gamete. When students pair their coins together, they simulate recombination, or sex, to determine their offspring's genotype and phenotype. For a lot of students, this lab is a big "a-ha" moment about meiosis and sex, and haploid and diploid.
Remember those dead individuals? Well now they are reincarnated as the offspring. A kid who died as a stumpy may come back as pincher (this is why all kids need to have three coins). Then the most important part: we count the number of each phenotype. We then circle back up and the process repeats. I have on my data table 10 generations worth, but we typically do 5-6.
The next lab day we calculate the allele frequency each generation to track the evolution of the population. We also have a lot of great conversations about behaviors we saw during the lab and how it's like real life. I love the conversations we have about this part.
Real Life Context
There are so many real life applications that can be discussed from this lab. Here's an incomplete list of things that come up and some discussion questions I usually raise.
Once all food is exhausted, I tell them how many corks they needed to survive. Usually I choose enough to kill off about 1/3 to 1/2 of the population. They return the corks to me, the dead individuals leave the population, and the winners are told to find a mate to reproduce with that will give them offspring most likely to survive. Typically this means everyone wants to mate with a pincher primarily, and a knuckle secondarily. Stumpys don't usually get much love.
Earlier in the year we do a "coin sex" lab where we explore probabilities of offspring inheriting alleles from various different genotypes of parents. I build on this experience with the Hunger Games Lab. A student who is a stumpy (AA) will label a coin with tape "A" on each side. A knuckler would have "A" on one side and "a" on the other. And a pincher would be "a" on both sides. Each side of the coin represents each homologous chromosome with the gene of interest. When students pair up with their mate, they both flip their coin. This simulate meiosis and Mendel's laws of segregation and independent assortment. The resulting allele face up is the one passed on in their gamete. When students pair their coins together, they simulate recombination, or sex, to determine their offspring's genotype and phenotype. For a lot of students, this lab is a big "a-ha" moment about meiosis and sex, and haploid and diploid.
Remember those dead individuals? Well now they are reincarnated as the offspring. A kid who died as a stumpy may come back as pincher (this is why all kids need to have three coins). Then the most important part: we count the number of each phenotype. We then circle back up and the process repeats. I have on my data table 10 generations worth, but we typically do 5-6.
The next lab day we calculate the allele frequency each generation to track the evolution of the population. We also have a lot of great conversations about behaviors we saw during the lab and how it's like real life. I love the conversations we have about this part.
Real Life Context
There are so many real life applications that can be discussed from this lab. Here's an incomplete list of things that come up and some discussion questions I usually raise.
- Kids always cheat. Nevertheless, the population always evolves to be more like the pinchers with "a" allele increasing in frequency. What is cheating? Why do we cheat? Do organisms cheat in real life?
- Sometimes Stumpys cooperate into a herd, and preserve their genotype. This brings up topics like group selection, disruptive selection, and speciation.
- The whole population shifts towards the pinchers. This helps us understand directional selection and gradualism. A common thing is see is that students always thing recessive alleles are bad. Here they realize that recessive alleles can actually be good, and thus increase in the population.
- Populations, not individuals, evolve. Most kids get this rock solid by the end of the lab. They also begin to understand how natural selection acts on the phenotype, but it's the genotype that evolves.
- Certain kids are sometimes popular as mates. Sometimes certain kids are monogamous. This brings us interesting topics of discussion about mate choice and sexual selection, and how that can influence the population.
- Bottlenecks. Sometimes I kill off a lot of the population. There's usually a point at which I dump all the food in one pile, and everyone sprints to the center (Hence the name "Hunger Games"). Some kids give up and die off. In this way it's less about the phenotypes and more about who was lucky enough to get to the pile. This can help students understand genetic drift and how sudden changes in the environment can affect a population.
- This year after I adopted the "nests" component, some students raided each other's nests at the end of the last round. This brought up a great conversation about parasitism. This reminded us how new behaviors, if advantageous, can be heavily rewarded in a population and can act as driving force in reproductive isolation and speciation. We talked about Cuckoos' nest parasitism and a neat recent article about Scrub Jays on Santa Cruz Island. There are a lot of parasites one could discuss.
Feel free to use and modify the lab to fit your needs. This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. If you make any great modifications or find cool new patterns, PLEASE share in the comments below. I'd love to hear more, or hear how people are benefiting from my work. If you have any questions, I'm happy to clarify too!
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