Study guide: Studying Populations
POPULATION: a group of individuals of the same species, living in a shared space at a specific point in time
Individuals in a pop. share a common environment they benefit from the same resources
They have a common environment, same resources, interaction during mating season, thriving and declining (caribou herds qc)
Studying populations reveals how various species evolve.
POPULATION SIZE: refers to the number of individuals in a population (4 factors affect this)
4 factors - Births, deaths, emigration and immigration
Births and immigration= death and emigration = stable population
MEASURING POPULATION SIZE
1) counting individuals: ( aerial photos, or counting individually)

2) Counting by sample area : randomly select sections of the study area , then estimate

Average # of individuals/ section Population size
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Area of section total study area

Section off into quadrats (rectangular areas marked off with rope)
Good for plants or slow moving animals or ones that don’t run from humans
3) Mark and capture
Install nets/cages
Count the captured animals and tag them
Release
Reinstall nets/cages
Count captured individuals a second time, then estimate size of population
# of marked animals recaptured = number of marked animals
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Total # of animals captured second time population size

Used for mobile animals, widely scattered in their habitat

POPULATION DENSITY: the number of individuals per unit of area or volume Population density = number of individuals -------------------------------- Space (area) occupied
Good food and water supply= high density
Climate, presence of predators, parasites or disease and disasters= increase or decrease

POPULATION DISTRIBUTION the way in which the individuals are dispersed within their habitat
1- Clumped (form groups) ex. Fish travel in schools ( certain areas of the populations habitat offer better living conditions)
2- Uniform (dispersed equally throughout the population habitat. (due to competition for resources)
3- Random (rare) randomly dispersed across the habitat

ECOLOGICAL FACTOR aspects of a habitat than can affect the organisms living there.
Examples: amount of food available, temperature, #of predators
Two types of factors: ABIOTIC AND BIOTIC
ABIOTIC NON LIVING ecological factors of physical or chemical origin BIOTIC LIVING ecological factors related to the actions of living organisms in the habitat

ABIOTIC (NON LIVING)
BIOTIC (LIVING)
Amount of light
Birth rate
Soil or water pH disease terrain
Amount of food
Depth of snow predation temperature competition Air humidity ( water %)
Human activity

LIMITING FACTOR: is an ecological factor that causes the density of the population to decrease
Absent, insufficient quantities or excess
If direct sunlight decreases = not enough photosynthesis
Too much water = root rot
PHOTOSYNTHESIS EQUATION
Sunlight energy+ 6o2+ 6h20= c6 h12o6+ 6 o2
Sugar – glucose
Photosynthesis, a process through which plants produce their food, is of utmost importance to us humans and other living beings.
Photosynthesis is the process by which plants use the energy from sunlight to produce sugar, which in simpler words is the 'fuel' used by all living things
BIOLOGICAL CYCLE: of a population is composed of alternating periods of rise and fall in its size. These periods are of fixed duration and are repeated annually.
Snowhare and lynx= 10 year cycle
When the hare pop. Rises the lynx have more food therefore reproduce more. As the lynx pop. Increases