Download populations

Lets pretend that we own an
island somewhere in the North
Sea. It is uninhabited.
We populate the island with 100
rabbits.
We return to the island 4 times
each year for the next 50 years
and count the bunnies.
What would happen if…
1. We then added a predator to the island.
2. We then added a competitor to the island.
3. We burnt off all the vegetation from half the island.
4. We introduced myxomatosis to the island.
Abiotic Factors
Temperature
Light
Water supply
Oxygen
Soil nutrients
Climate
Carbon dioxide
weeds on a patch of disturbed ground
understory plants in a coniferous wood
wildebeeste in sub-saharan Africa
yeast in fermenting fruit
moorland plants on the high fells
blue tits in suburban gardens
maize plants in a field
Biotic Factors
Food supply
Predation
Disease
Competition
Parasitism
rabbits on downland
oak caterpillars in a temperate forest
moles in a lowland grassland
ash seedlings in a temperate wood
pin worms in UK children
density dependent?
density independent?
The data below give the average number of
fertilised eggs produced in their lifetime by females
of different species (fecundity).
Oyster
100 x 106
Cod
9 x 106
Stickleback
5 x 102
Winter moth
200
Mouse
Dogfish
Woman
Elephant
50
20
10
5
How many fertilised eggs must survive if a
population remains stable?
Suggest why the value for Stickleback is so much
lower than Cod.
Suggest a relationship between pre-reproductive
mortality and fecundity.
Each female salmon lays 3200 eggs in a gravelly shallow
in the river in autumn. 640 fry (young fish) enter a lake
near the shallow in the following spring. 64 smolts (older
fish) leave the lake one year later and migrate to the sea.
Two adult fish return to the spawning grounds 2.5 years
later; they spawn and die.
Calculate the % mortality for the salmon for each of the
periods described in the passage.
Calculate the % survival from these figures.
Draw a survivorship curve for salmon by plotting %
survival against time.
What is the pre-reproductive mortality for salmon (%)?
Would you expect the survivorship curve for humans to
show a different pattern?