POPULATIONS AND COMMUNITY INTERACTIONS
Feb 24, 2016
POPULATIONS AND COMMUNITY INTERACTIONS
Population growth
What are some of the factors that
affect the size of a
population?
Four factors affect the size of a population
Immigration: when individuals move into a population´s range. (Imigração)
Birthrate: number of individuals that are born in a population in a period of time. (Natalidade)
Emigration: when individuals move out of the range. (Emigração)
Death rate: number of individuals that die in a population in a period of time. (Mortalidade)
Individuals are ADDED to the population
Individuals are REMOVED from the population
Community Interactions
One population
benefits from it but the
other is not affected by it
One population
benefits from it and the other is
harmed by itOne population is harmed by it but the other is not affected by it
Both populations benefit from
the interaction
Both populations are harmed
by the interaction
Competition: same or different species (Competição)
Organisms attempting to use the same ecological resource at the same time and place.
Populations inhibit one another (both populations are harmed by the interaction).Two gazelles competing for land.
Predation: one organism captures and feeds on another organism (Predação)
Predator-prey relationship: (Relação predador-presa)
• One animal (predator) captures and feeds on another animal (prey).
• Lions and buffalo
Who is the predator and who is the prey?
Predation
Herbivore-plant relationship: (Herbivoria)• One animal (herbivore) feeds on
plants.• Caterpillar and plants
Symbiosis: two species living closely together (Simbiose)
Mutualism (Mutualismo)• It is obligatory; both populations benefit from
the relation.• Legume plant and nitrogen-fixing bacteria
located in nodules on their rootsThe bacteria helps the plant to absorb water and minerals. The plant produces organic food for itself and also for the bacteria.
Symbiosis
Protocooperation (Protocooperação)• It is NOT obligatory; both populations
benefit from the relation.• Birds and cows
The bird eats ticks or lice, that are parasites of cows.
Symbiosis
Parasitism (Parasitismo)• The parasite (A) exploits the host (B), but does
not kill it outright.• Ticks (A) and dogs (B)
• “Athletes foot” on human• Worms and human intestine
The tick eats skin and blood of the dog.
Symbiosis
Commensalism (Comensalismo)• The commensal (A) benefits while the host (B)
is not affected.• Remora fish (A) and sharks (B)
Remora fish swims attached to the shark -so that it uses the host as transport, protection and also feeds on food remains.
Symbiosis
Amensalism (Amensalismo ou antibiose)• One species (A) produces a chemical compound
(as part of its normal metabolic reactions) that is harmful to the other species (B) A unaffected; B inhibited.
• Fungus (A) and bacteria (B)The fungus (Penicillium) produces antibiotics, penicillin, that limits the bacterial (Staphylocoque) growth.
Symbiosis
Inquilinismo• An specie (A) uses another one (B) as a place to
live (like a house) but doesn't actually use any resources from B.
• Epiphytes (A) and trees (B) The bromeliad gets all it's nutrients from the environment AROUND the tree. The tree neither benefits nor is harmed by the bromeliad "setting up residence" in it's branches.