Lecture 1 JD

Question 1

What are biotic interactions?

Answer 1

interactions between individuals and populations which determine the species composition and functioning of habitats, ecosystems and biomes

Question 2

What is a biotic factor?

Answer 2

a living part of an ecosystem –> animals, plants, fungi, bacteria and protists

Question 3

What is an abiotic factor?

Answer 3

physical or nonliving factor that shapes an ecosystem –> temp, light and water

Question 4

What is the Red Queen hypothesis, and who proposed it?

Answer 4

• organisms must constantly adapt and evolve in order to survive in an evolutionary arms race.
• Leigh van Valen proposed this hypothesis

Question 5

What is natural selection?

Answer 5

a process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype or genetic constitution

Question 6

What are two ways natural selection acts in?

Answer 6

• density-dependent manner
• density-independent manner

Question 7

Density-dependent manner

Answer 7

the intensity of selection and the rate of mortality increases with increasing population size

Question 8

Density-independent manner

Answer 8

the rate of mortality is uniform irrespective of the population size

Question 9

What is competition?

Answer 9

interaction between individuals brought about by a shared requirement for a resource and leading to a reduction in the survivorship, growth and or reproduction of at least some of the competing individuals concerned

Question 10

What does density-dependent selection often arise through?

Answer 10

through competition among individuals, either as intraspecific competition or interspecific competition

Question 11

Where does intraspecific competition occur?

Answer 11

within species competition

Question 12

Where does interspecific competition occur?

Answer 12

between species competition

Question 13

Intraspecific competition

Answer 13

• occurs when many individuals try to exploit the same resource
• results in some individuals contributing less to subsequent generations

Question 14

What does the self-thinning rule predict?

Answer 14

it predicts that plants will decrease in population density (self-thin) as the total biomass of the population increases

Question 15

The self-thinning rule

Answer 15

(look at slides)
- as the population biomass increases, the number of survivors decreases because individual organisms are gaining biomass at the expense of their competitors, and this constant trade-off between abundance and biomass is universal across all plant species

Question 16

What is carrying capacity ‘K’?

Answer 16

• the number of people, animals or crops that a region can support without environmental degradation
• the maximum amount/biomass of a species population in a given habitat

Question 17

Mathematical models of population growth

Answer 17

look at slides