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What are the types of mortality?
- Type I- mortality concentrated on old age animals
- Type II- mortality is constant over time
- Type III- mortality nearly constant with age
What method needs a cohort?
What is a cohort?
- a group of animals of the same species
- identified by a common characteristic (age)
- which are studied over a period of time as part of a scientific investigation
What do life tables show?
- a snapshot picture of the population
- way to examine the ages of animals in a population & understanding the role age plays
Why are life tables important?
- show how birth and death rate are related
- ecologists gain insight about populations strategy for survival
- help identify weak links in the population
- models a populations dynamics
What does x stand for?
What does fx stand for?
number of individuals observed alive each year
What does lx stand for?
number of individuals surviving at the start of age interval
What does dx stand for?
number of individuals dying within a specified age interval?
What does qx stand for?
- age specific mortality rate
What ways can we get a life table?
- direct method
- approximate method