Survival is Not Enough
An organism survives for 100 years but never has offspring. What is its evolutionary fitness?
Zero! Fitness is defined by the ability to survive AND reproduce.
In the Rock Pocket Mouse populations, how did the dark fur mutation happen?
By chance because it was a mutation - mutations are random!
It was NOT the environment (dark rocks)
What was the specific "Selection Pressure" that caused the mouse population at Location B to change?
Predators & substrate color.
Do individual Rock Pocket Mice change their fur color during their lifetime to match the rocks?
No. Individuals do not evolve; populations evolve over generations.
True or False - If a mutation makes a mouse faster but also makes it sterile (unable to have babies), that mutation will show up in the next generation(s).
False. Traits only increase in frequency if they are inherited by offspring.
When did the dark fur mutation first appear?
Some mice already had dark fur before the lava rock appeared. - it's not magic and can't just poof into appearance.
Why do we say natural selection is not random, even though mutations are?
Because the environment "selects" specific traits that are advantageous for survival in that specific setting.
A student says, "The mice turned black because they needed to hide." What is wrong with the word needed?
Traits don't appear because of need. They appear randomly, and those who happen to have them survive better.
EX: those who happen to have faster speed to escape danger survive and reproduce more, so the trait becomes more common.
At Location A (light sand), dark mice were born but stayed rare. Why didn't they take over like they did at Location B
It provided no selective advantage against predators. So, the trait didn't help them survive and reproduce in that environment.
What role does the environment play in natural selection?
It determines which mice survived ONLY.
Environment does NOT create new traits
Light mice decrease rapidly. What is most likely the cause?
Predation OR poor camouflage
Based on the data, if the volcanic rock at Location B stays dark for 100 more years, what will the population look like?
Mostly dark with few or a very small number of light colored mutants.
Explain why "Dead-end survivors" (those who live long but don't reproduce) are invisible to evolution.
Evolution is a change in the population over time. If the genes aren't passed on, the population doesn't change.
True or False - The environment causes mutations organisms need.
False The volcanic rock did NOT make mice turn dark
Surviving organisms must also ____ for evolution to occur?
Reproduce
If a population has zero genetic variation (they are all clones), can natural selection happen if the environment changes?
Nope. Natural selection requires variation & without it the population will likely go extinct.
How do mutations occur?
Mutations happen randomly, not because an organism "needs" them.
And don't say they are inherited! (they can be but they don't start that way, its a random change in the DNA then it can be inherited)
Dark moths become more common. Is this a cause or and effect?
Effect
Write a 3 sentence "Cause-and-Effect Chain" for why the Peppered Moth population went from light to dark during the industrial Revolution.
Required Keywords - Variation, Selection Pressure, Reproduction.
The population had variation in wing color. The soot from factories became a selection pressure that favored dark wings. Dark moths survived and reproduced more, increasing the frequency of the dark trait in the population.