Chapter 5: Estimating Population Growth Rates Flashcards
(41 cards)
exponential (or geometric) growth
- (per capita) rate of change in abundance that is not affected by density
- growth = increase or decrease
examples of exponential decline
- Hawaiian monk seal: 3.9% decline per year
- Devil facial disease
Malthus dilemma
contrast between exponential growth vs arithmetic growth
Malthus dilemma: geometric growth
- population
- increases by a constant factor of 2
Malthus dilemma: arithmetic growth
- food
- increases by constant difference of 2
λ =
Nt + 1 / Nt
when λ = 1
the population is stationary
when λ < 1
the population decreases geometrically
when λ > 1
the population increases geometrically
% change per year =
(λ-1) * 100
NT =
No * λT
discrete time
change in N over 1 year
discrete time equation
Nt + 1 = Nt (λt)
continuous time
instantaneous change
continuous time equation
dN/dt = rN
r =
slope of a line
continuous (exponential) growth equation
dN/dt = rN
continuous (exponential) growth
- the rate of change in population size at each instant in time
- the instantaneous per capital growth rate
per capita growth rate
the average contribution each individual makes to population change
how to convert between λ and r
r = ln(λ)
λ = e^r
when r = 0
the population is stable
when r < 0
the population decreases exponentially
when r > 0
the population increases exponentially
advantages of λ
translates easily into ‘percent annual growth’ an easily understandable metric
