Modelling Populations II

Question 1

Population growth

Answer 1

increase in the number of individuals within a population over time

Question 2

Why study Population Growth?

Answer 2

• studying population growth can help to understand factors associated with population increase/decrease
• helps to make prediction about future population size

Question 3

What are the three types of growth?

Answer 3

• geometric
• exponential
• logistic.

Question 4

What is Growth Rate?

Answer 4

• rate of population growth (“steepness” of curve)
• dN/dt = change in number of individuals per time

Question 5

Geometric Growth

Answer 5

growth of a population with pulsed reproduction (where generations do not overlap and where successive generations differ by a constant ratio)

Question 6

What kind of curve does Geometric Growth produce?

Answer 6

a J-shaped curve

Question 7

Exponential Population Growth

Answer 7

• continuous population growth in an unlimited environment
• overlapping generations
  non-pulsed (continuous) reproduction

Question 8

Do Geometric and Exponential Growth actually happen?

Answer 8

• yes, but only for shoer periods of time when resources are very abundant

Question 9

Why is it unrealistic of geometric and exponential growth to occur for long periods of time

Answer 9

• per capita death rates will increase as densities increases, and birth rates will decrease as resources diminish

Question 10

Palynology

Answer 10

the study of pollen found in sediment cores

Question 11

What is an example of Exponential Growth?

Answer 11

Scots pine
- they grew at an exponential rate as the glaciers of the last ice age retreated in Britain
- by studying the pollen content in sediment cores, we can reconstruct pollen accumulation rates
- scots pine was able to expand without much competition after ice age

Question 12

Under what specific circumstances does exponential growth happen?

Answer 12

• small population size at the beginning
• favourable environment
• establishment in new territory

Question 13

Logistical Population Growth

Answer 13

if and when resources become limited, population growth rate will slow and eventually stop

Question 14

What kind of curve does the Logistic population growth produce?

Answer 14

a sigmoidal (s-shaped) curve

Question 15

Carrying Capacity

Answer 15

• K
• the population size at which growth stops
• occurs at the number of individual of a particular species that the local environment can support

Question 16

K is usually reached when per capita:

Answer 16

birth + immigration = death + emigration

Question 17

Why do Carrying Capacities Exist?

Answer 17

• all resources, whether its water, light, food, space, etc. are limited
  a given environment can only support so many individual of a given species

Question 18

MSY

Answer 18

maximum sustainable harvest that can occur without decreasing the population growth rate
- hump shapes curve