Population Ecology Flashcards
Define “Individual”
1 organism in a population
Define Population
A group or organisms of the same species that live together
Define Community
Several populations living together
Define Ecosystem
A community of living organisms and their relationship to each other and the environment.
Define population density
The number of organisms living in the population
What influences the population density to increase or decrease?
Immigration
Emigration
Mortality
Natality
Name and explain 4 limiting factors in an environment
1) Density dependant factors. Factors that are directlu affected by the density. Eg: Resources like food/water
2) Density Independant Factors. Factors that are not controlled by density. Eg: Natural disasters
3) Environmental Resistance. The combined effect of all limiting factors that affect growth of a population
4) Carrying capacity. The maximum number of individuals a land can support
Name and explain the 3 sampling methods
1) Mark-Recapture. Capture number of organisms. Marked then released. Another group captured from same population. Count number already marked animals.
2) Quadrats. Stand away from area. Throw quadrate over your shoulder. Gives random sample. Results representative of area
3) Census. Count directly by observation
What precautions need to be taken with the Mark-Recapture method?
No marking that will influence animals lifestyle (Camoflage etc)
Marks must last until next capture
Must be waterproof or weather resistant
What precautions need to be taken with the Quadrat method
The organism must be stationary
The organism must be small enough to fit into the quadrat.
What precautions need to be taken with the Census method?
organism must be visible
organism must be big enough
organism must be stationary
What is the calculation for the Mark-Recapture method?
Population size = M X C
———–
R
What is the calculation for the Quadrat method?
total area of quadrat
Which method(s) are direct and indirect counting methods respectively
Indirect - MR method, Quadrat.
Direct - Census
What is the importance of random sampling?
Indirect methods of estimating population size are most accurate when the segment of the population counted is selected randomly
