Lecture 2 & 3 Life histories

Question 1

2 ends of reproductive strategy continuum

Answer 1

r-selection and k-selection

Question 2

R- selection

Answer 2

Selection for high population growth rates
- an advantage in newly disturbed habitats and uncrowded condition.
- r is the intrinsic rate of increase of a population.
(“live fast, die young”):
- Short life spans, rapid development, early maturation, low parental investment, high reproduction rates
- Most insects, small vertebrates such as mice, weedy plant species

Question 3

K-selection

Answer 3

Selection for lower growth rates in populations that are at or near K, the carrying capacity for a population.
- This is an advantage in crowded conditions; efficient reproduction is favoured.
(“slow and steady”):
- Long-lived, develop slowly, late maturation, invest heavily in each offspring, low reproduction rates
- Large mammals, reptiles such as tortoises and crocodiles, and long-lived plants such as oak and maple trees

Question 4

trade offs

Answer 4

Organisms allocate limited energy or resources to one function at the expense of another.

• The larger the investment in each individual offspring, the fewer offspring can be produced.
• Investments: Energy, resources, time and loss of chances for other activities such as foraging.