Life Tables and Population Growth Flashcards
What factors can determine population behaviour?
Individual mortality and reproduction schedules
What is survivorship?
The amount of individuals in a population that are expected to survive to any specific age
What are they types of survivorship curves and what determins the type on a graph?
Type I
Type II
Type III
The shape of the curve determins the type
What kind of mortality rate causes a Type II survivorship curve?
Constant mortality throughout life
What kind of mortality causes a Type III survivorship curve?
Realtively high mortality rate earlier in life
What do we have to do to use survivorships in calculations?
Convert to probabilities
Divide the raw survivorships by the initial number
What do life tables summarise?
Births and deaths for organisms at different ages of their lives
They show quantaties like survivorship for different age classes
What are the two types of life tables?
Cohort life tables aka generational life tables - represents age-specific rates over the lifetime of a cohort of organisms born in a relatively short period of time
Period life tables - represents age-specific rates during a specific time period of a certain population
What symbol represents survivorship in cohort life tables?
lx
What symbol represents age-specific survival?
Sx
What is the equation for age-specific survival?
Sx = (lx+1)/lx
What are some ways life tables can be used?
Measures of population growth
Net reproductive rate
Annual growth rate
Generation time
What is generation time?
The time between births of each cohort
What is the definition of Net Reproductive Rate?
Average number of female offspring produced by one individual female over her lifetime (from birth to death)
What interpretations can we take from net reproductive rate?
A measure of per-generation population growth rate
A measure of fitness (lifetimes reproductive success)
