Download Populations

Populations
Determining a Population size
• How many fish can live in a pond?
• How Many deer can live in a forest?
• What factors can you think of might change this number?
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Factors affecting Population Growth
• 1. Births– number of surviving offspring (natality)
• 2. Deaths– number dying from all causes (mortality)
• 3. Immigration
– Number entering an area
• 4. Emigration
– Number leaving an area
Population growth
Population growth =
(births+ immigration) – (deaths + Emigration)
Example
• The turkey population in Durham ontario has seen a massive spike in
the number of wild turkey populating the area.
• Question: The number of new births is estimated at 200 young making the total
population close to 2000 birds. If only 50 have been hunted and 50 die from
natural causes how many birds can we expect in the next year if no immigration or
emigration occurs?
• Answer:
– Births= 200; deaths= 100; no immigration or emigration
– Population growth = 200 – 100 = 100 individual
– Next year approximately 2100 birds
Carrying capacity
• The maximum number of individuals (the largest population of a
species) that the environment can support in a given area and this is
determined by specific limiting factors
• http://www.youtube.com/watch?v=8FPMP41LYJ8
Limiting Factors
• Limiting factors (also known as a "constraining" factors) limits the
growth or development of an organism, population, or process.
• Population growth has a limit that is determined by;
– Abiotic factors -Climate, water, space (habitat)
– Biotic factors – food, competition, predators, parasites, disease
(bacteria)
Factors affecting carrying capacity
• Materials:
– the amount of food, nutrients, water, shelter.
• If a population continues to grow it will soon out grow its food supply
• Death or starvation may occur *********
• Food Chains:
– Populations are limited by predator, prey sustainability, competition
• Hunting, Disease, Parasites, Habitat loss, Pollution
Competition
• Competition for food, mates, space
– Interspecific: individuals from different species compete for resources
– Intraspecific: individuals of the same species compete
• Competition is necessary
– decreases over crowding/ old/ weak and therefore the possibility of disease
Population Density
• The number of organisms living in a given space
• Think about the population density of wolves in Ontario compared to
the population density of Canadian geese.
– What differences exist between these two animals that account for different
densities?
– Different Animals need different amounts of space to roam, forage, hunt and
find mates and both require different amounts of food to live
Factors affecting population density
• Density dependent:
– Factors that increase in significance as a population grows
– Depend on the size of the population
– ex. Food, space, mates, spread of disease
• Density Independent:
– Factors that do NOT depend on population size
– Ex. Forest fires, drought, temperature
Disease
Ex. Bubonic plague/black death
Limiting factors
• What factors will affect the whooping crane?
ABIOTIC
BIOTIC
Pollution
Fish available
Water pH, or temperature
Competing cranes
Climate changes
urbanization
viruses
Bacteria, disease
Sampling Populations
• How might you count all the worms in The Soil?
Recap
• What are 4 factors of population growth
• What is carrying capacity?
• What are 9 limiting factors that affect carrying capacity?
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Disease
Pollution
Density
Starvation
Habitat/space
Food/ water
Competition
Hunting
Climate
Activity
• In groups of 3 brainstorm as many ideas as possible as to how the
coyote population has become so large….
• How is it being controlled….
– https://www.youtube.com/watch?v=G8oO-GypOLA
Population Increase
Population Control
Increases
Control
Birth
Guard animals=emigration
Large food supply
Keeping food barricaded
Quality of mothers milk
guns
Large habitat
traps
Few predators
Chemical compounds
Less competition
Predation
Sterilization
Trapping relocating