Population dynamics Flashcards

1
Q

What are the 4 factors that control population

A
  • Birth rate
  • Death rate
  • Immigration
  • Emigration
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2
Q

What is the equation to determine current population size

A

Past population + birth rate +immigration - emigration - death rate = current population

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3
Q

How would a population increase

A

Population will increase if the reproduction (birth) rate is high and the death rate is low

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4
Q

How would a population decline

A

Population will decline if the reproduction (birth) rate is low and the death rate is high

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5
Q

What are 4 factors that control birth rates

A
  • Age of population (reached sexual maturity)
    -Ratio of males : females
  • Breeding cycles + timing (seasons)
  • How many times/ how often an individual can produce offspring
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6
Q

What are 4 factors that control death rates

A
  • Food availability
  • Drought (water availability)
  • Predation
  • Disease
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7
Q

What is an expression that describes a population stable in size

A

B + I = D + E

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8
Q

What is an expression that describes a population that is declining in size

A

B + I < D + E

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9
Q

What is an expression that describes a population that is increasing in size

A

B + I > D + E

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10
Q

What does “B” mean relating to population size

A

Birth rate

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11
Q

What does “I” mean relating to population size

A

Immigration

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12
Q

What does “D” mean relating to population size

A

Death rate

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13
Q

What does “E” mean relating to population size

A

Emigration

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14
Q

What is an expression that describes change in population size

A

B + I ≠ D + E

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15
Q

How do you work out death rate

A

Number of deaths / number of organisms within the population

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16
Q

How do you work out birth rate

A

Number of births / Number of organisms within the population

17
Q

Define carrying capacity

A

Number of individuals that an
ecosystem/area can support
sustainably without damaging or over-exploiting the environment

18
Q

Define density independent factors

A

factors where the density of the population has no effect on the chances of survival, eg flood, volcanic eruptions

19
Q

Define density dependent factors

A

factors where the chances of survival are dependent on the density of the populations, eg disease, food supply

20
Q

What is death rate

A

The number of deaths per 1000 population per year

21
Q

What is birth rate

A

The number of offspring per 1000 population per year

22
Q

What is emigration

A

Reduction in the population of the individuals leaving to another area

22
Q

What is immigration

A

Addition of new individuals to the population from another area

23
Q

What are 4 examples of density dependent factors

A
  • Disease
  • Competition (for..)
  • Food supply
  • Predation
24
What are 4 examples of density independent factors
- Wild fires - flooding - Temperature change - Earthquakes
25
Density independent factors are..
..mostly abiotic
26
Density dependent factors are..
..mostly biotic
27
What is the definition of Sigmodial population growth
A growth pattern in which an organism's population density rises slowly originally in a fresh setting, in an acceleration stage; then rises quickly approaching an exponential growth rate
28
What does the Sigmodial population growth curve consist of
It consists of four phases: the lag phase, the log phase, the stable fluctuating phase
29
What happens at the lag phase on a Sigmodial population growth graph
Population growth is slow as the population is adapting to its environment therefore rate of reproduction is low
30
What happens at the log phase on a Sigmodial population growth graph
Rapid exponential growth and no limiting factors due to relatively low density
31
What happens at the stable fluctuating phase on a Sigmodial population growth graph
Population is no longer increasing in size. Birth & death rates are balancing each other. The population has reached carrying capacity. The population will tend to fluctuate around this level
32
What are three examples of artificial population control
- Culling - Eradication of invasive species - Pest control
33
What is culling (example)
Purposely reducing a population e.g. deer are culled as they cause damage to woodlands and graze on vegetation and because there are no wolves to naturally hunt them
34
Explain what is meant by r-selected species
Smaller species that respond rapidly to low survival rates. - Reach sexual maturity quickly - Reproduces quickly, - Produce many young - Low parental involvement - Low probability of survival
35
Explain what is meant by k-selected species
Species that respond slowly from a decline in population. - Reach sexual maturity at an older age - Produce a small amount of young - Longer gestation time - High parental involvement - High probability of survival
36
What type of release would k-selected species need
Soft release
37
What are three examples of k-selected species
- Rhino - Elephant - Whales
38
What are three examples of r-selected species
- Spider - Rabbits - Frogs