Biology 301 - Ecology and Evolution -
Chapter 12 Exam Questions With All
Correct Detailed Answers A+ Pass
What is demography? - Answer ✔✔- The study of (the structure and growth of)
populations
What type of techniques does demography use to predict the growth of populations
(both natural and laboratory)? - Answer ✔✔- Mathematical techniques.
What basic processes have direct effects on population size? - Answer ✔✔- Births &
immigration (cause population increase) along with Deaths and Emigration (cause
population decrease). ∆N=(B+I) minus (D+E).
What does a geometric (discrete) growth model represent? - Answer ✔✔- A model of
population growth that compares population sizes at regular time intervals, showing how
populations with discrete generations and discrete reproductive bouts fluctuate in
seasonal patterns of population increase and decrease.
What is the equation for geometric (discrete) growth model for multiple time intervals? -
Answer ✔✔- N₍t₎ = N₍₀₎λ⁽ᵗ⁾
What does lambda (λ) in the geometric (discrete) growth model represent? - Answer
✔✔- It is the ratio of population size at any time to the population size 1 time unit earlier,
or the "per capita growth rate" / "finite rate of increase".
What happens when λ=1? - Answer ✔✔- The population is constant.
What happens when λ<1? - Answer ✔✔- The population is decreasing.
What happens when λ>1? - Answer ✔✔- The population is increasing.
What does the exponential (continuous) growth model represent? - Answer ✔✔- A
model of population growth in which the population increases continuously at an
exponential rate, has overlapping generations with year round reproduction and exhibits
smooth curve of population increase as a function of time.
What is the equation for exponential (continuous) growth model? - Answer ✔✔- N₍t₎ =
N₍₀₎e⁽ʳᵗ⁾ where N = # of individuals after t time units, N₍₀₎ = the initial population size, r =
exponential growth rate / instantaneous rate of increase, t = time units and e = base of
the natural logs (~2.72).
, What is the conversion for growth rates? - Answer ✔✔- λ=e⁽ʳ⁾ thus r=ln(λ).
What happens when r=0? - Answer ✔✔- The population is constant.
What happens when r<0? - Answer ✔✔- The population is decreasing.
What happens when r>0? - Answer ✔✔- The population is increasing.
Definition of density independent: - Answer ✔✔- Factors that limit population size
regardless of population's density, such as climatic events.
Definition of density dependent: - Answer ✔✔- Factors that affect population size in
relation to the population's density.
Two types of density dependence and their defintions: - Answer ✔✔- 1. Negative
density dependence = when the rate of population growth decreases as population
density increases. 2. Positive density dependence = when the rate of population growth
increases as population density increases.
Common factors of negative density dependence: - Answer ✔✔- Most common factors
causing negative density dependence are limiting resources (food, nesting sites,
physical space). As population's size increases, resources are divided among more and
more individuals causing per capita resources to decline which can then cause
developmental and reproduction issues in the individuals.
Example of negative density dependency: - Answer ✔✔- Raymond Pearl observed how
as fly numbers increased, competition for food became more intense and adults had
fewer progeny and shorter lifespan.
What is positive density dependence also known as? - Answer ✔✔- Inverse density
dependence or Allee effect are other known names for positive density dependence,
which is when the rate of population growth increases as the population density
increases.
Where does positive density dependence typically occur? - Answer ✔✔- It occurs
typically in low density populations, which may make it hard to find mates, especially
when sex ratios are uneven.
Example of positive density dependence: - Answer ✔✔- Populations of cowslip primrose
(Primula veris) with fewer than 100 individuals produced fewer seeds per plant than
larger populations. As population size increased, so did the seeds per cowslip.
What is the equation for density independent continuous growth? - Answer ✔✔- N₍t₎ =
N₍₀₎e⁽ʳᵗ⁾ where N = # of individuals after t time units, N₍₀₎ = the initial population size, r =
Chapter 12 Exam Questions With All
Correct Detailed Answers A+ Pass
What is demography? - Answer ✔✔- The study of (the structure and growth of)
populations
What type of techniques does demography use to predict the growth of populations
(both natural and laboratory)? - Answer ✔✔- Mathematical techniques.
What basic processes have direct effects on population size? - Answer ✔✔- Births &
immigration (cause population increase) along with Deaths and Emigration (cause
population decrease). ∆N=(B+I) minus (D+E).
What does a geometric (discrete) growth model represent? - Answer ✔✔- A model of
population growth that compares population sizes at regular time intervals, showing how
populations with discrete generations and discrete reproductive bouts fluctuate in
seasonal patterns of population increase and decrease.
What is the equation for geometric (discrete) growth model for multiple time intervals? -
Answer ✔✔- N₍t₎ = N₍₀₎λ⁽ᵗ⁾
What does lambda (λ) in the geometric (discrete) growth model represent? - Answer
✔✔- It is the ratio of population size at any time to the population size 1 time unit earlier,
or the "per capita growth rate" / "finite rate of increase".
What happens when λ=1? - Answer ✔✔- The population is constant.
What happens when λ<1? - Answer ✔✔- The population is decreasing.
What happens when λ>1? - Answer ✔✔- The population is increasing.
What does the exponential (continuous) growth model represent? - Answer ✔✔- A
model of population growth in which the population increases continuously at an
exponential rate, has overlapping generations with year round reproduction and exhibits
smooth curve of population increase as a function of time.
What is the equation for exponential (continuous) growth model? - Answer ✔✔- N₍t₎ =
N₍₀₎e⁽ʳᵗ⁾ where N = # of individuals after t time units, N₍₀₎ = the initial population size, r =
exponential growth rate / instantaneous rate of increase, t = time units and e = base of
the natural logs (~2.72).
, What is the conversion for growth rates? - Answer ✔✔- λ=e⁽ʳ⁾ thus r=ln(λ).
What happens when r=0? - Answer ✔✔- The population is constant.
What happens when r<0? - Answer ✔✔- The population is decreasing.
What happens when r>0? - Answer ✔✔- The population is increasing.
Definition of density independent: - Answer ✔✔- Factors that limit population size
regardless of population's density, such as climatic events.
Definition of density dependent: - Answer ✔✔- Factors that affect population size in
relation to the population's density.
Two types of density dependence and their defintions: - Answer ✔✔- 1. Negative
density dependence = when the rate of population growth decreases as population
density increases. 2. Positive density dependence = when the rate of population growth
increases as population density increases.
Common factors of negative density dependence: - Answer ✔✔- Most common factors
causing negative density dependence are limiting resources (food, nesting sites,
physical space). As population's size increases, resources are divided among more and
more individuals causing per capita resources to decline which can then cause
developmental and reproduction issues in the individuals.
Example of negative density dependency: - Answer ✔✔- Raymond Pearl observed how
as fly numbers increased, competition for food became more intense and adults had
fewer progeny and shorter lifespan.
What is positive density dependence also known as? - Answer ✔✔- Inverse density
dependence or Allee effect are other known names for positive density dependence,
which is when the rate of population growth increases as the population density
increases.
Where does positive density dependence typically occur? - Answer ✔✔- It occurs
typically in low density populations, which may make it hard to find mates, especially
when sex ratios are uneven.
Example of positive density dependence: - Answer ✔✔- Populations of cowslip primrose
(Primula veris) with fewer than 100 individuals produced fewer seeds per plant than
larger populations. As population size increased, so did the seeds per cowslip.
What is the equation for density independent continuous growth? - Answer ✔✔- N₍t₎ =
N₍₀₎e⁽ʳᵗ⁾ where N = # of individuals after t time units, N₍₀₎ = the initial population size, r =
