Interactions Among Living Things

Adapting to the Environment Every organism has a variety of adaptations that are suited to its specific living conditions. Adaptations of organisms in the desert ecosystem create unique roles for each organism.

Niche The special role an organism plays within a habitat. Helps reduce competition for food and other resources. Includes: –Type of food organism eats –How and where it obtains food –Which other species use the organism as food –Physical conditions it requires

Bay-Breasted Warbler Feeds in the middle part of the tree Yellow-Rumped Warbler Feeds in the lower part of the tree and at the bases of the middle branches Cape May Warbler Feeds at the tips of branches near the top of the tree Spruce tree 3 Species of Warblers & Their Niches

Relationships Between Populations 3 Types of Interactions Among Organisms –Competition –Predation (Predator & Prey) –Symbiosis These are density-dependent limiting factors

Competition Struggle between organisms to survive in a habitat with limited resources Ex. Some plants use chemicals to ward off their competition. Release toxic or poisonous, chemicals to prevent them grow growing near their space.

Predation One organism kills and eats other organism Predator –Organism that does the killing –Adaptations: Speed, hearing, etc. Prey –Organism that is killed. –Adaptations: Camouflage, protecting covering, warning color, mimicry

Effect of Predation on Population Size

Symbiosis Relationship between two species that benefits at least one of the species. Types of Symbiotic Relationships –Mutualism (+, +) Both species benefit Ex. Bacteria in intestine –Commensalism (+, 0) One helped, one neither helped nor harmed Ex. Bird and tree –Parasitism (+, -) One helped (parasite), one hurt (host) Ex. Tapeworm and you

Types of Limiting Factors Density – Dependent Limiting Factor –How much they affect the population is influenced by how big the population is. –Ex. Competition for food, water, habitat Density –Independent Limiting Factor –How much they affect the population is not influenced by how big the population is.

Density Independent Limiting Factors Severe weather Global disaster Fire

What are Some Possible Explanations for this Population Graph?

Summary Questions Name and define the three major types of interactions among organisms. List the three types of symbiosis. For each one, explain how the two organisms are affected. How are parasitism and predation similar? How are they different?