Year 12 Bio recently played a game to illustrate how mutations enter the gene pool and change in frequency, and how mutations can be helpful, harmful or neutral (and this can change if the environment changes!)
Equipment needed for this game:
plastic forks with the middle prongs removed
In this game, students 'live' in different populations at tables around the room. These populations all have a similar niche and are trying to gain access to the same resource - maltesers. These maltesers are found in bowls on a table in the middle of the room.
The game progresses through several rounds or 'generations.'
In the first round, each group has the same adaptation for gathering their resource - plastic forks. Students needed to gather a resource and keep it balanced all the way back to their table, where they could deposit the resource and pass on the fork to the next person. Each group roughly gathered the same amount of maltesers, and they all survived to produce the next generation.
In the next generation one of the populations had a mutation - they lost the middle prongs of their fork! We played another round, and the group missing the middle prongs were unable to gather any maltesers, because the gap in the middle was too big!
Alas, this was a harmful mutation. It didn't enter the gene pool of the overall population because it failed to help them gain enough resources to survive, and unfortunately that group couldn't pass their genes or alleles onto the next generation.
(We let the group come back in with a normal fork though, so they could keep playing).
The next generation had another mutation - their adaptation to help them gather was a tablespoon! This turned out to be a helpful mutation, as it was easier to balance and they could gather resources faster than the other groups.
As they were more successful, in the next generation more groups had tablespoons, as the helpful allele became more frequent in the gene pool.
After a few tablespoon generations another mutation occurred - a teaspoon! I thought this mutation would also be harmful but it turned out to be neutral, as having a smaller spoon didn't seem to affect the ability to balance a malteser in it.
However!!! Suddenly the environment changed!!
The bowls of maltesers became shot glasses of maltesers. Suddenly having a smaller teaspoon was an advantage in the new environment, as the teaspoon adaptation was too large to get into the bottom of the shot glass.
The group with the smaller teaspoon SHOULD have had much greater access to maltesers and the next generation should have had a lot greater frequency of alleles for smaller teaspoons.
However, my class are resourceful and very competitive, and the tablespoon groups quickly worked out that they could use the handle of the tablespoon to scoop out maltesers! So that point was sort of lost, but the rest of the game was good to illustrate how mutations arise and change in frequency in populations over generations, depending on whether they help or harm the organisms' ability to survive or reproduce in their environment.
Mutations in the story:
Fork (at the start)
Fork with prongs missing (harmful, gap too wide for maltesers)
Tablespoon (helpful - easier to balance than fork)
Teaspoon (neutral - turned out to be no different from table spoon)
Change of environment to shot glass (teaspoon advantage now to fit in the glass)