Population

POPULATIONS
• Population - the number of individuals of the same species in a given area at a given area
• Factors affecting Populations
1. Available resources (e.g. food, water, shelter)
2. Activities of other organisms (e.g. predators, disease-causing parasites)
3. Organism's own characteristics (e.g. gestation period, number of young produced, nurturing of young, migratory)
4. Time of day or year (e.g. tides, seasons, nocturnal or diurnal)
5. Weather (e.g. amount of rainfall, cyclone, drought)
• Population Change - depends on birth, death, immigration and emigration on the whole
Population Change = ( B + I ) – ( D + E )
• Population Density - The number of organisms in a given area can affect the population due to competition for resources such as food water and nesting places, and spread of disease.
Population Density = number of individuals
area occupied
The population density may be measured in different ways (e.g. 7/km of kangaroos, 8000/mL of bacteria).


• 3 Population Sampling Techniques
1. Quadrat
2. Transect
3. Mark-Recapture Method

Assignment:


"Ecosystems can and do change but all the relationships in the system are in a dynamic balance!"

 Write your answers the following terms and questions:

Reproductive rate:


Recruitment:


Biotic potential:


Exponential increase:


Population explosion:


Replacement level:


Density-dependent:


Population density:


Critical number:


Threatened:
Endangered:


Natural enemies:


Introduced species:


Territoriality: individuals or groups claiming a territory and defending
                       it against others of the same species

Have humans upset the natural balances in ecosystems, if so, how?




Wildlife management:


Carrying capacity:  maximum population of a species that a given habitat will support without the habitat being degraded over the long term.





Monoculture:


POPULATION GROWTH CURVES
S-curve:


J-curve:
MECHANISMS OF POPULATION EQUILIBRIUM
- Predator - prey and Host- parasite relationships
- Introduced species
- Territoriality
- Plant-herbivore relationships
- competition between plant species

ECOLOGICAL (NATURAL) SUCCESSION
- defined as the orderly, gradual progression from one community to
   another

Climax ecosystem:


Primary succession:


Secondary succession:


Ecological upsets:

Ecological collapse:

What effect do humans have on ecosystems?





* fourth principle of ecosystem sustainability
   - Biodiversity is maintained