Why a species lives here and not there

Science · Ecology & Conservation · ages 20-21

Name ______________________ Date ____________

What does the peak of a tolerance bell curve mark?
- Where most individuals cluster: the best conditions
- Where predators hunt most
- Where no individual can live
What is a species' tolerance range?
- The miles it migrates yearly
- The zoos that house it
- Conditions where a species can survive and reproduce
A narrower tolerance range means a wider geographic range.
Circle one: True False
Transplants past the edge thrive. What stopped the species?
- Too much sunshine
- Old age of the seeds
- A barrier or rival barred it, not physiology
Name the three usual suspects when a species is missing.
- Rain, wind, and sunshine
- Tolerance, dispersal barriers, and rivals or predators
- Luck, color, and size
Type how many usual suspects explain an absence.
Answer: ______________
A reserve shrinks to a fraction of its area. What happens to richness?
- It always doubles
- Richness falls, following the species-area link
- Area never matters
A student reads one warm year as proof of adaptation. What is wrong?
- Single years mislead; track vital rates across sites and years
- Warm years never happen
- Plants ignore temperature fully

Answer key

For grown-ups. Fold this page away before handing over the rest.

Where most individuals cluster: the best conditions · The curve crests where conditions suit the species best.
Conditions where a species can survive and reproduce · Tolerance spans the full livable band from sweet spot to edge limits.
False · Narrow curves restrict ground, as the shiner's thin oxygen band shows.
A barrier or rival barred it, not physiology · Thriving newcomers prove the ground is livable, so arrival or enemies blocked it.
Tolerance, dispersal barriers, and rivals or predators · Physiology, blocked arrival, and enemies each make a different prediction.
3 · Tolerance, barriers, and rivals or predators: three suspects.
Richness falls, following the species-area link · Richness tracks area, so habitat loss forecasts species loss.
Single years mislead; track vital rates across sites and years · Only tracked survival, growth, and reproduction across sites and years reveal the trend.