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 WarblerFeeds in the middlepart of the tree

Yellow-Rumped WarblerFeeds in the lower part of the tree andat the bases of the middle branches

Cape May WarblerFeeds at the tips of branchesnear 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?