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
Define predator-prey relationship
A negative feedback mechanism which dictates the predator:prey ratio
Give 2 examples of a predator-prey relationship
Lion- Zebra
Aphid- Ladybug
What is the impact of social organization
Social organization is mechanism to surviveEg; packs, division of labour etc
What limits does a Census have?
Expensive
Not suitable for large areas
Double counting/miss counting
What impacts does a food web have?
Afood web depicts feeding connections in anecological community. Change in size of one population could affect the changes in another population.
Species that compete for resources are said to be in….
Competition
Name and explain the 2 kinds of competition
Interspecific competition. Competition between different species.
Intraspecific competition. Competition between organisms within a species.
Name a 4 resources species might compete for
Water/food
Space
Shelter
Mates
How would two species that compete for resources live together?
Co existance
What is co existance?
Two or more species living together using different resources
What is resource partitioning?
Living together but using different resources to suit needs
If a species was out competed what would happen?
The species would be forced to emigrate
Define ecological niche
The specific requirements for a population to live
What is ecological succession?
The development of a new ecosystem over time
The 2 kinds of succession are…
Primary and secondary
What is primary succession
The sequence of organisms that occupy a new land beginning from bare rock
What is secondary succession
A habitat that has been disturbed
The first organisms to get to the land after a disturbance are…
Pioneers
The species that are the last before a disturbance are the….. Species
Climax species
