1. D. Survivorship and Selection Type

2. Survivorship curves:
tell us how long individuals survive in a population

3. type I species with a high survival rate of their young
most individuals are expected to die only when old
eg. humans

4. type II:
- species in which individuals die at a constant rate from hunting, disease, etc.
- eg. squirrels, bees, most reptiles

5. type III: - species with most individuals die when young
- many babies are born, but few survive very long
eg. tobacco, salmon, oysters

6. Type I Type II Type III 1000 100 Number of survivors [log scale] 10
Type I
100
Type II
Number of survivors
[log scale] 10
Type III
Percent of life span

7. 2. ‘r’ and ‘K’ selection
a. ‘r’ refers to species whose population is well below the carrying capacity and so can still grow exponentially with a rate ‘r’
b. ‘K’ refers to populations that are almost at the carrying capacity [K]
c. ‘r’ and ‘K’ refer to different strategies that will ensure the survival of the species
d. the environment, size of the organism, number & size of offspring, maturity, life expectancy and frequency of reproduction all influence this

8. ‘r’ strategy
unstable environment, density independent

9. small size of organism
energy used to make each individual is low

10. many offspring are produced
early maturity

11. short life expectancy
each individual reproduces only once

12. Type III 1000 100 Number of survivors [log scale] 10 0 20 40 60 80 100
100
Number of survivors
[log scale] 10
Type III
Percent of life span

13. ‘K’ strategy
stable environment, density dependent

14. large size of organism
energy used to make each individual is high

15. few offspring are produced
late maturity, often after a prolonged period of parental care

16. long life expectancy
individuals can reproduce more than once

17. Type I Type II 1000 100 Number of survivors [log scale] 10
Type I
100
Type II
Number of survivors
[log scale] 10
Percent of life span

18. handout;
work on parts B and C