POPULATION
ECOLOGY NOTES
MATRIC IEB LIFE
SCIENCE
, POPULATION ECOLOGY
The study of interactions of organisms with their physical and biological environments
and how these determine the distribution and make-up of populations within an
ecosystem
- Biosphere: part of the earth where organisms are found
- Ecosystem: made up of groups of different species of organisms that interact with each other
and with the environment
- Organism: an individual form of life composed of a single cell or complex of cells which can
grow and reproduce EG. Bacteria, protest, plant
- Community: a group of different species that inhabit and interact
- Species: a group of closely related organisms, very similar to each other. Capable of
interbreeding and producing fertile offspring
- Individual: single organism capable of independent existence
- Population: a group of organisms of the same species that occupy the same area and can
breed freely with each other
- Demographics: statistical information about the population
,The size of a population
The total number if individuals in the population.
• Natality – birth rate of a population, normally
expressed as the number of live births per thousand
individuals per year
• Mortality – death rate of a population, normally
expressed as the number of deaths per thousand
individuals per year
• Immigration – one way movement of organisms into an
area where they become established
• Emigration – one way movement of organisms out of
an area to become established
CLOSED POPULATION: A population where there is no
immigration or emigration
Eg. A fish pond that does not have a stream running into or out
of it.
, HOW IS GROWTH OF A POPULATION
REGULATED
• The number of favourable conditions in which a population lives will WHAT DETERMINES SURVI
determine the speed at which the population grows. 1. tolerate the environment
they live eg: physical environ
• If a few individuals enter an unoccupied area where all conditions for growth competition, predation
are favourable: 2. access the natural resourc
• ie: unlimited food, water, and no predators, obtain energy and nutrients,
mates
• the population will grow at the maximum possible growth rate
These requirements form the
• ie: it will grow exponentially. (increase more and more) ecological niche of the indivi
all the requirements needed
BUT WHAT STOPS EXPONENTIAL GROWTH IS survival & reproduction
the amount of resources decreases eg: less food
à intraspecific competition : food, water, space, shelter and
suitable mates.
The total number of factors [limiting factors] that stop a
population from reproducing at its maximum rate is known as:
ENVIRONMENTAL RESISTANCE
And the resulting growth pattern is à Logistic growth pattern
ECOLOGY NOTES
MATRIC IEB LIFE
SCIENCE
, POPULATION ECOLOGY
The study of interactions of organisms with their physical and biological environments
and how these determine the distribution and make-up of populations within an
ecosystem
- Biosphere: part of the earth where organisms are found
- Ecosystem: made up of groups of different species of organisms that interact with each other
and with the environment
- Organism: an individual form of life composed of a single cell or complex of cells which can
grow and reproduce EG. Bacteria, protest, plant
- Community: a group of different species that inhabit and interact
- Species: a group of closely related organisms, very similar to each other. Capable of
interbreeding and producing fertile offspring
- Individual: single organism capable of independent existence
- Population: a group of organisms of the same species that occupy the same area and can
breed freely with each other
- Demographics: statistical information about the population
,The size of a population
The total number if individuals in the population.
• Natality – birth rate of a population, normally
expressed as the number of live births per thousand
individuals per year
• Mortality – death rate of a population, normally
expressed as the number of deaths per thousand
individuals per year
• Immigration – one way movement of organisms into an
area where they become established
• Emigration – one way movement of organisms out of
an area to become established
CLOSED POPULATION: A population where there is no
immigration or emigration
Eg. A fish pond that does not have a stream running into or out
of it.
, HOW IS GROWTH OF A POPULATION
REGULATED
• The number of favourable conditions in which a population lives will WHAT DETERMINES SURVI
determine the speed at which the population grows. 1. tolerate the environment
they live eg: physical environ
• If a few individuals enter an unoccupied area where all conditions for growth competition, predation
are favourable: 2. access the natural resourc
• ie: unlimited food, water, and no predators, obtain energy and nutrients,
mates
• the population will grow at the maximum possible growth rate
These requirements form the
• ie: it will grow exponentially. (increase more and more) ecological niche of the indivi
all the requirements needed
BUT WHAT STOPS EXPONENTIAL GROWTH IS survival & reproduction
the amount of resources decreases eg: less food
à intraspecific competition : food, water, space, shelter and
suitable mates.
The total number of factors [limiting factors] that stop a
population from reproducing at its maximum rate is known as:
ENVIRONMENTAL RESISTANCE
And the resulting growth pattern is à Logistic growth pattern
