Key Vocabulary
What word means differences among individuals in a population?
Variation
True or False: All individuals in a population have the same traits
False
What kind of graph is often used to show how traits are spread in a population?
Histogram or bar graph.
What does “environment” mean in science?
Surroundings where organisms live (including climate, predators, resources).
What animal started eating the newts?
Snakes
What is the word for traits that help an organism survive and reproduce?
Adaptive trait (adaptation)
Give one example of a trait that can vary in a population.
Examples: fur color, poison level, beak size, etc.
What does the “height” of a bar in a distribution graph represent?
Number of individuals with that trait
Give an example of an environmental factor that can affect survival.
Examples: predators, temperature, food availability.
What trait helped the newts survive?
High poison level
What does “distribution” of traits mean in a population?
How traits are spread across individuals in a population
Why is variation important for populations’ survival?
It gives some individuals an advantage if the environment changes.
If more individuals in a population have the same trait, how does that show up on the graph?
The bar will be taller.
Why can a trait be adaptive in one environment but not another?
Because survival depends on the match between trait and environment.
Why did high-poison newts have more offspring over time?
Because snakes ate the low-poisonous newts, the high-poisonous newts survived and reproduced.
What is the process by which populations change over time?
Natural Selection
How do scientists collect evidence of variation in traits?
By making observations, collecting data, or running simulations.
What does it mean if the distribution of traits changes over time?
Traits are becoming more or less common.
What environmental change affected the newt population in this chapter?
The presence of snakes.
What happened to the distribution of poison levels in the newt population?
Distribution shifted toward more high-poison individuals.
What term describes when a trait helps an organism survive in one environment but not in another?
Context-dependent adaptation (or adaptive in some environments but not others)
If there is no variation in a population, what might happen when the environment changes?
The whole population may die out.
How can scientists use trait distribution to make predictions about future populations?
They can see which traits may become common in the future.
How does environmental change drive natural selection?
Traits that help survival become more common, others decrease.
Summarize how environmental change led to the newt population becoming more poisonous.
Snakes created an environmental pressure → low-poison newts died → high-poison newts survived and reproduced → population became more poisonous.