Population Ecology Flashcards
Term 2, year 10
Define ‘population size’
Number of individuals.
Note: larger populations may be more stable than smaller as there is greater genetic variability and more potential to adapt to environmental changes.
Define ‘population density’
Number of individuals per unit geographic area, e.g. number per square metre.
Give examples of density dependent and independent factors.
Density dependent: disease, competition, predation, food, nesting sites, mates.
Density independent: sunlight, temperature, rainfall (often abiotic).
PANDA PAW
Predators Availability of resources Nutrient supply Disease/pathenogenic spread Accumulation of wastes
Phenomena
Abiotic factors
Weather conditions
How might population be distributed?
- Random
- Clumped
- Uniform
Define ‘natality’
Increases population size as offspring are added.
Define ‘immigration’
Increases population size as individuals have moved into the area from somewhere else.
Define ‘mortality’
Decreases population as some individuals get eaten, die of old age or get sick.
Define ‘emigration’
Decreases population as have moved out of the area to live somewhere else.
Population size equation
(Immigration + Natality) - (Mortality + Emigration)
Lincoln Index Formula
P = n1 x n2/n3
Define ‘R selection’ and ‘K selection’
R selection- only puts a small investment of resources into each offspring. Babies grow and mature rapidly.
K selection- Babies are entering a competitive world and invest heavily in each offspring.
Quadrat sampling method (density)
total number of individuals counted/number of quadrats x area of each quadrat
Quadrat sampling method (population size)
mean number per quadrat x total area/area of each quadrat
