Grasslands: Life histories Flashcards
Define a population
A group of species that breeds with each other
What is a useful characteristic of a population and why?
Age distribution because it is very sensitive to ecological influence
How is age distribution described?
Using a life table which tabulates mortality by age. Data is used to investigate causes of changes e.g. mortality could show predation
How is survivorship calculated?
Number surviving / total number born (per year)
What is suggested by a survivorship curve?
Population strategies
How many types of survivorship curve are there?
3
Describe a Type I survivorship curve
Most individuals die late in life. They have few offspring and invest much time and effort into them.
Describe a Type II survivorship curve
Individuals die at a uniform rate
Describe a Type III survivorship curve
Most individuals die at a young age. They have many offspring and invest little time and effort into them.
How is age-specific mortality calculated?
Number of dying / number surviving
Give five life history events that affect population growth
Maturity, inter-birth interval, generation time, age at death, litter size
What does population in a given year depend on?
The population and growth rate of the year before
What type of growth is seen in a population that breeds seasonally?
Geometric growth
What type of growth is seen in a population that breeds continuously?
Exponential growth
Which type of population growth is faster?
Exponential
