Spend now or save for later

Science · Ecology & Conservation · ages 20-22

Name ______________________ Date ____________

A survivorship curve drops steeply at first, then flattens. What does that mean?
- Death strikes evenly at every age
- Most individuals die young while the few survivors live long
- Almost everyone survives until sudden old age death
Why is the growth versus reproduction clash a real trade-off?
- One limited budget funds both, so spending here starves there
- Animals simply prefer one option over the other
- Growth and reproduction use unrelated resources
Which animal packs everything into one giant reproductive burst followed by death?
- Most songbirds, which breed every spring
- Large mammals, which nurse young for years
- Salmon, which breed once hugely then die
Why does higher fecundity often mean smaller offspring?
- A fixed budget split among more young leaves less per offspring
- Small young always survive better than large ones
- Mothers prefer tiny babies whatever the budget
Adult survival in a population is unpredictable from year to year. Which schedule wins?
- Save everything for a big late brood
- Breed early and often rather than waiting
- Skip breeding until conditions turn perfect
Deaths pile up right after first breeding in a life table. What does that reveal?
- Breeding was free and cost nothing at all
- Predators only attack newborn babies
- The survival price paid for that reproductive effort
A trade-off means the animal simply prefers one option over another.
Circle one: True False
A new island species has safe adults but brutal competition among juveniles. Which strategy wins?
- Breed early and often with tiny uncared young
- Hold back and invest heavily in a few strong young
- Stop reproducing entirely and live forever

Answer key

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

Spend now or save for later W1-mt_eGwlydfDWO-s1

Most individuals die young while the few survivors live long · Early steepness is young death. The flat tail is the lucky few living on.
One limited budget funds both, so spending here starves there · A shared budget forces the clash. Gains in one function demand losses in another.
Salmon, which breed once hugely then die · One burst then death is semelparity, the salmon and annual plant schedule. Birds and mammals spread efforts.
A fixed budget split among more young leaves less per offspring · Division is destiny: more shares from one purse means thinner slices. Smaller young then survive worse unaided.
Breed early and often rather than waiting · A future that may never arrive is a bad savings account. Spending now beats saving for nothing.
The survival price paid for that reproductive effort · Life tables write costs in deaths. A post breeding pileup is the receipt for reproduction.
False · Preference needs no budget, but trade-offs do. Without a shared limit there is no forced choice.
Hold back and invest heavily in a few strong young · Safe adults can afford to wait, while fierce young competition rewards quality. Few well funded young win.