Population Dynamics

Question 1

What is the definition of population?

Answer 1

A group of sexually interbreeding or potentially interbreeding individuals

Question 2

What is the definition of species?

Answer 2

A group of interbreeding or potentially interbreeding natural populations, which are reproductively isolated from other such groups

Question 3

What are metapopulations?

Answer 3

• Occur in fragmented habitats
• Connected by limited migration
• Characterised by extinction and recolonisation: populations are transient
  If environmental conditions are good then species will move out to sink populations but if conditions are bad they move back to source populations

Question 4

Why are populations studied?

Answer 4

• Aids conservation e.g. endangered species Red List - survey regarding the number of individuals in a particular species - mammal based
• Aids management e.g. fisheries
• Determine characteristics:
  i) Population distribution/dispersion (size, shape and location that populations occupy)
  ii) Density (number per unit area) -> abundance

Question 5

What is population distribution (i)?

Answer 5

• All individuals -> distribution = geological range
• Environmental conditions
• ## Variable - Metapopulation / Local subpopulation

Question 6

What is a uniform distribution?

Answer 6

Caused by territories - trying to get as far away as possible within a limited area

Question 7

What is a clumped distribution?

Answer 7

Depends on life history - bachelor / female groups (herds) - asexually produced organisms

Question 8

What is a random distribution?

Answer 8

Can’t explain what is happening? Maybe movement / don’t know enough about the environment

Question 9

What is distribution a measure of?

Answer 9

Dispersion

Question 10

What is population density (ii)?

Answer 10

• Determining abundance - Abundance = density x area

Question 11

How can individuals be counted?

Answer 11

• Not possible
• Can’t be sure all have been counted
• Take samples and generalise - gives estimates - use quadrats - extrapolate - gives estimate of density
• Samples vary
• Distribution effects how varied the samples are
• Mark / recapture can be used to study mobile species - tagging, marking, different individuals

Question 12

What is the Lincoln/Lincoln-Peterson index for measuring density?

Answer 12

N = nM/R
N = Population 
M = Number captured (pre-marking)
R = Number recaptured (marked)

Question 13

What are species limited by?

Answer 13

Adaptations depending on abiotic and biotic factors / range is variable depending on climate conditions

Question 14

What are population dynamics?

Answer 14

It is a flux:

• Add individuals (birth, immigration)
• Remove individuals (death, emigration)

Question 15

What are the 2 types of population dynamics?

Answer 15

1. Spatial

2. Temporal

Question 16

What is spatial dynamics?

Answer 16

• Dispersal
• E.g. In less than 60 years Eurasian collared doves expanded their range to the furthest corners of Europe
• Eurasian collared doves began to spread out of Turkey into Europe early in the 20th century

Question 17

What is temporal dynamics?

Answer 17

Age structure

Question 18

What are patterns of survival?

Answer 18

• Survivorship curve (see graph)
• High survival among the young e.g. Dall sheep
• High mortality among the young e.g. Mackerel
• 3 types of survivorship curve (see graph)