When Environments Shift
What is an environmental change?
A change in biotic or abiotic conditions that affects organisms.
What happens to a population when survival and reproduction increase?
The population size increases.
What is extinction?
The complete loss of a species.
What is speciation?
The formation of new species over time.
What type of data best supports claims about population change?
Long-term population data.
Name one abiotic environmental change.
Climate change, drought, temperature change, volcanic activity (any one).
What environmental change might cause a population to increase?
Increased food availability, fewer predators, or improved climate conditions.
Name one environmental change that can lead to extinction.
Habitat loss, climate change, pollution, or introduction of invasive species.
What is required for speciation to occur?
Reproductive isolation.
Why are single observations weak evidence?
They may not represent long-term trends.
How can a sudden environmental change affect population size?
It can increase or decrease survival and reproduction rates.
How could a decrease in predators lead to population growth?
More individuals survive long enough to reproduce.
Why does habitat destruction often cause population decline?
It reduces resources needed for survival and reproduction.
How can geographic isolation lead to speciation?
Populations evolve independently under different conditions.
How can fossil evidence support claims of extinction or speciation?
It shows appearance and disappearance of species over time.
Why are populations with greater genetic variation more likely to survive environmental change?
Some individuals may already have traits suited to the new conditions.
Why might an invasive species rapidly increase in a new environment?
It may lack natural predators or competitors.
How can a species’ specialization increase its risk of extinction?
Specialized traits may not work if conditions change.
Why does speciation usually take many generations?
Genetic differences accumulate gradually through natural selection.
Why is correlation alone not enough to prove causation?
Other variables may explain the change.
Evaluate why the rate of environmental change matters when predicting population outcomes.
Rapid changes may outpace adaptation, while gradual changes allow natural selection to act.
Evaluate evidence that an environmental change—not chance alone—caused a population increase.
Data would show consistent increases linked to specific environmental changes across time.
Evaluate why extinction is more likely when multiple environmental changes occur at once.
Combined pressures reduce survival faster than adaptation can occur.
Evaluate how environmental differences can provide evidence that speciation occurred.
Distinct traits match different environments, indicating divergence over time.
Evaluate which type of evidence best supports a claim that environmental change caused population decline.
Multiple data sources showing consistent trends linked to environmental shifts.