NATURAL SELECTION & FITNESS
What does “fitness” mean in biology?
Ability to survive and reproduce in an environment.
Give one example of an innate behavioral adaptation.
Migration, hibernation, suckling, taxis.
Natural selection acts on individuals or populations?
Populations.
Which type of evidence shows how closely organisms are related based on base sequences?
DNA/molecular evidence.
What happens to populations repeatedly exposed to pesticides?
Resistant individuals survive & reproduce.
Natural selection requires limited resources, competition, and ________.
Genetic variation.
Give one example of a learned behavior.
Habituation, imprinting, classical conditioning.
What is geographic isolation?
Physical separation preventing breeding between groups.
On a cladogram, what do nodes represent?
Common ancestors.
Why does antibiotic resistance make infections harder to treat?
Resistant bacteria are no longer killed by the antibiotic; they reproduce.
Traits that increase reproductive success will ______ in future generations.
Increase in frequency.
What is a structural adaptation?
Physical feature that increases survival (camouflage, beak shape, gills).
What must occur for two groups to officially become separate species?
Reproductive isolation (cannot interbreed).
Why is DNA the best evidence for evolution?
It shows exact similarities/differences, reveals relatedness, and tracks evolutionary history.
Does the environment cause mutations that help insects survive?
No — mutations already exist; selection favors resistant individuals.
A drought favors plants with low water requirements. What happens to their frequency over time?
Their frequency increases because they are better adapted.
What is a physiological adaptation?
Internal function helping survival (venom production, antifreeze proteins).
A flood separates mice by creating two environments. After many generations, they cannot breed. What has occurred?
Speciation.
The closer two organisms are on a cladogram, the more ______ they share.
Traits/common ancestry.
What happens to the gene pool when populations are separated a long time?
They diverge; allele frequencies change independently.
Explain why the peppered moth shifted from light to dark during the Industrial Revolution.
Environmental change increased selective pressure → dark moths were camouflaged & survived to reproduce.
Explain how natural selection AND reproductive isolation both contribute to speciation.
Isolation stops gene flow → different environments select different traits → genetic divergence → new species.
What is the most specific taxonomic level?
Species.
Explain why pesticide effectiveness decreases over time.
Pesticides kill susceptible individuals → resistant ones reproduce → resistance spreads → chemical becomes ineffective.