Variation & Survival Advantage

Activities to try

1. 1

   Be the predator: a camouflage survival game

   Why it works: Variation that already exists gives some individuals a survival or mating advantage in a particular environment; because those individuals survive and reproduce more, the proportions in the population shift over generations. The advantage lives in the match between trait and environment, not in the trait by itself, and no individual changed itself on purpose.

   1. Before the first round, predict out loud which colour variant will dwindle in this environment and WHY.
   2. Act as a hungry bird: against a dark bark background scattered with moths that vary in colour, tap to 'eat' as many as you can before the timer runs out; you will probably find it easier to spot and grab the moths that contrast with the bark (here, the pale ones) and miss more of the well-hidden dark ones.
   3. After the round, count the survivors by colour, let the survivors 'breed' to fill the next generation, and watch whether the population shifts toward the better-hidden colour.
   4. Press the background-swap button (dark bark to pale lichen) and run another round; notice that now the dark moths stand out and are more likely to get eaten, so the advantage has reversed.
   5. Run a drought round where a slider makes the drought worse, so drought-resistant plant variants tend to survive and set seed more often than thirsty ones, and a mate-choice round where brighter birds are more likely to be chosen and leave more chicks, so surviving, finding mates, and reproducing all appear.
2. 2

   Hands-on paper-beetle selection

   Why it works: Differential survival of pre-existing variants shifts a population's makeup over generations, and the same trait can be an advantage in one habitat and a disadvantage in another.

   1. Scatter mixed green and brown paper 'beetles' on a brown cloth.
   2. Before grabbing, predict which colour will dwindle and WHY.
   3. Act as a bird: grab as many beetles as you can in ten seconds.
   4. Count the survivors by colour, 'breed' the survivors (add more of the surviving colour), and repeat for several rounds.
   5. Try the same game on a green-moss cloth and compare what happens.
3. 3

   Predict-the-survivor scenarios and trait-environment matching

   Why it works: The reasoning can be stated and justified: advantage is relative to a specific environment, covers surviving AND finding mates AND reproducing, and works by selection among existing variation.

   1. For each scenario (a species varying in one trait in a stated environment), predict which variant has the survival or mating advantage.
   2. Justify the prediction with the trait-environment link in a full sentence, e.g. 'the pale speckled moth is hidden on the pale, lichen-covered bark, so birds eat it less and it is more likely to live to breed'.
   3. Match each trait to the environment where it would help (thorn size vs grazers; speed vs predators; drought resistance vs a dry summer; bright colour vs mate choice).
   4. Answer a two-environments item where the correct variant flips when the setting changes (pale fur in snow vs on dark rock).
   5. Put the steps in order: variation already exists, some variants survive/mate more in this environment, they leave more offspring, proportions shift.