Population dynamics 2 Flashcards
Define: modelling population dynamics
using life table to assess population viability
What is R0?
average reproductive success of individuals in a population
What is the equation for R0?
Σ lxbx
What can be used to predict numbers in future generations + equation?
Ngeneration 2 = R0 x Ngeneration1 = Number of individuals and R0 currently can be used to predict numbers in future generations
What is used instead of generations and why?
But generations can be hard to define, so normal to consider change over time
What are discrete time steps also known as?
generations
How do discrete time models model population dynamics?
= time moves in steps like generations rather than on a continuous scale
Simplified to Nt+1 = λNt = finite rate of increase = parameter that describes intrinsic ability of a population to increase or decrease determined by the 4 demographic processes
- Even though immigration and emigration is usually ignored
How do continuous time models model population dynamics?
Same model but time is considered to be a continuous variable
Nt+1 – Nt = change in numbers between now and the future = time step- what happens to pop growth in 1 time step- to model over continuous times steps = ∆N = small change in numbers that happen instantaneously- expressed on graph
Slope on graph described by dN/dt = little bit of change in N over a little bit of time
dN/dt = r N = this collapsed down into r- exactly the same model as discrete
What is the change in population size determined by?
dN/dt = r N = change in size of population overtime is determined by whether there are more births than deaths = very simple model:
- If r is + = slope of graph is + = + growth
- If r is - = slope of graph is - = - growth
do lambda and r express the same thing?
Lambda and r express the same thing which is product of 4 demographic processes
