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WBiology > Population Dynamics > Flashcards

Population Dynamics Flashcards

1
Q

What is a population?

A

Individuals of a single species living in the same area at the same time

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2
Q

What are the characteristics (definition, types) of a population?

A
  1. Size
  2. Density
    - Number/space
  3. Dispersion: pattern of distribution
    - Clumped
    - Uniform
    - Random
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3
Q

What are the factors affecting population growth?

A

Population Growth:
Birth rate/fecundity (depends of number of individuals in population in reproductive years) + immigration > death rate + emigration

Population Decline:
Death rate/mortality + emigration > birth rate + immigration

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4
Q

What is demography and what does it depend on?

A
  • The study of factors that affect growth/decline of population
  • Birth rate and death rate depend on age and sex of individuals in populations
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5
Q

What are the characteristics of demography?

A

Age structure, generative time, sex ratio

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6
Q

What is age structure and the types?

A
  • Relative number of individuals of each age in a population
  1. Stable population
  2. Positive population growth
    - Population explosion (many pre-reproductive individuals)
  3. Negative population growth (decline in population)
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7
Q

What is generative time and its effect on population growth?

A
  • Average length of time between birth of individuals and birth of offspring
  • If there are 2 populations of same size/fecumity/mortality, the one with short generation time experiences faster growth
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8
Q

What is the sex ratio and what are the cases it will affect population growth?

A
  • Proportion of individuals of each sex in population
  1. Mate for life: must have equal sex ratio for maximum growth
  2. Harem: unequal sex ratios doesn’t matter
  3. Alpha couple: unequal sex ratio doesn’t matter
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9
Q

What are the types of graphs and what does N represent?

A

Let N = population size

Age pyramid, growth curve, survivorship curve

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10
Q

What is an age pyramid?

A

Number of individuals of each sex in each age category

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11
Q

What is a growth curve and the types?

A

-Plots of population size versus time

Exponential
Logistic
Sinusoidal

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12
Q

What is a survivorship curve and the types?

A

Plots number of individuals in a cohort still alive at each age

Type 1: low mortality until old age
Type 2: equal mortality throughout life
Type 3: very high mortality in youth but survivors live long life

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13
Q

What describes the humans’ population growth and what explains it?

A

Went from type 1 to type 3 curve

  • Medicine
  • Agriculture
  • Industrial revolution (technology)

Resulted in exponential growth

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14
Q

What is the impact of humans exceeding the carrying capacity?

A
  • Depleting resources
  • Habitat destrubtion
  • Famine
  • Global warming
  • Biological magnification (accumulation of heavy metals)
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15
Q

What are the factors influencing the balance of populations?

A

Fecundity

Interactions

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16
Q

How does fecundity influence the balance of populations? What are the types and when are they advantageous?

A

Altering fecundity to use energy optimally

  1. Semiparity
    - Organisms invest most energy throughout life
    - Used in single large reproductive episode
    - Advantageous when living in harsh environment
  2. Iteroparity
    - Organisms produce fewer offspring over span of many seasons
    - Invest smaller amounts of energy in each reproductive episode
    - Advantageous when environment is more stable and favourable (can afford to give energy for reproduction)
17
Q

What is a community?

A

many species living in same area

18
Q

What are mathematical models used for?

A

Used to predict population growth of species; tells you instantaneous growth of population

19
Q

What are the types of models?

A

Exponential

Logistic

20
Q

What results in the exponential growth model? Is it realistic?

A
  • No limit on population increase

- Unlimited resources (unrealistic as there will be competition for sunlight, food, water, space, etc.)

21
Q

What does the logistic model focus on?

A
  • Focuses on density/carrying capacity (K) - maximum population environment can support
  • If N is close to carrying capacity then population growth is 0
22
Q

What are the phases for the logistic model?

A

Early phase: slow growth because number of reproductive individuals is small

Exponential phase: rapid growth because number of reproductive individuals is large and lots of resources

Negative phase: slow growth because of competition for resources

23
Q

What are the equations for exponential model?

A

dN/dt=rN, r=b-d

t=0.69/r

24
Q

What is the equation for logistic model?

A

dN/dt=rN(K-N/N)

25
Q

How does a density dependent factor affect population? What are some examples?

A
  • Intensifies as population increases
  • Affects fecundity and mortality when population density is high
  • Sets limits to population growth (determines carrying capacity)
  • Eg. food, sunlight, disease, nesting sites, mates
26
Q

How does a density independent factor affect population? What are some examples?

A
  • Affects same percentage of individuals regardless of population density
  • Prevent population from ever reaching K
  • Eg. fire, climate, natural disasters
27
Q

What is a life history?

A

events that affects organisms’ schedule of reproduction and death

28
Q

What are the 2 life history strategies?

A
  • K selected

- R selected

29
Q

What is a K-selected population?

A
  • Equilibrium
  • Living at or near carrying capacity
  • Must survive and reproduce with limited resources
30
Q

What is a R-selected population?

A
  • Opportunistic
  • Live in open habitats with little competition
  • Variable environment where population fluctuates
  • Favour individuals with high growth rate
31
Q

Answer for K selected populations:

Maturation Time
Lifespan
Death Rate
# of Offspring/Reproductive Episode
# of Reproductive Episodes in Lifetime
Size of Offspring
Generation Time
Parental Care of Offspring
A 
Long
Long
Low
Few
Many (iteroparity)
Large
Long
Extensive
32
Q

Answer for R selected populations:

Maturation Time
Lifespan
Death Rate
# of Offspring/Reproductive Episode
# of Reproductive Episodes in Lifetime
Size of Offspring
Generation Time
Parental Care of Offspring
A 
Short
Short
High
Many
One (semelparity)
Small
Short
None
33
Q

What is biotic potential?

A

maximum rate population can increase when no limits on growth rate

34
Q

What is environmental resistance?

A

all factors acting to limit growth of population

WBiology (8 decks)

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