This aesthetic, in-depth, neatly typed document summarises the entire strand 1 of the IEB grade 12 mind action series textbook: population and community ecology. it includes the full strand 1 syllabus as well as additional class and research notes.
Strand 1 - Population Ecology
1. POPULATION ECOLOGY:
Ecology: The study of the interactions of organisms with their physical and biological environments
• Population ecology is concerned with the fluctuations in size of a population & factors that regulate
fluctuations.
• Individuals make up a population
• Populations make up communities
• Communities make up ecosystems (with non-living factors)
• Ecosystems make up biosphere
Biosphere: Part of earth where living organisms are found
Ecosystem: Groups of different species of organisms
Organism: Individual form of life
Community: Group of different species that interact in an area
Species: Group of closely related organisms capable of producing fertile offspring
Population: Group of organisms of the same species that occupy the same area at the same time
Population size:
Total number of individuals in a population
• Natality: birth rate
• Mortality: death rate
• Emigration: move out of (exit)
• Immigration: move into
(in a closed population, only natality & mortality affect size)
Population growth:
Individuals increase exponentially, therefore there are more demands on resources.
This causes environmental resistance, which causes birth rate & immigration to decrease and death
rate & emigration to increase.
Environmental Resistance: Total number of factors that stop a population from reproducing at a
maximum rate
, Eventually a balance is reached: Population stabilises. This is the carrying capacity.
Carrying Capacity: Population density that an environment can support
Population fluctuates around carrying capacity = self-regulating.
Stable & Unstable Populations:
• Stable: numbers decrease when size exceeds carrying capacity and increase when numbers fall
below capacity
• Unstable: Population exceeds carrying capacity:
- rapid deterioration of population & habitat
- cant support population = extinction
Estimation of population size:
• Direct methods;
Counting every individual = census. Used for:
- Populations with organisms large enough to be seen
- Where area is not too large
- Slow moving organisms eg. tortoise
- Stationary organisms eg. plants
- Organisms that usually stay in fixed position eg. barnacle
If the area is too large:
- Arial photographs eg. penguins/seals
- Helicopters eg. elephants/buffalo
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Lindyprinsloo. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.09. You're not tied to anything after your purchase.
