Ecological Interactions “When one tugs at a single thing in nature, he finds it attached to the rest of the world.” ~John Muir, naturalist, Sierra Club founder

What is a Niche? A niche is a species way of life, or the role the species plays in its environment. It includes: feeding relationships, reproduction, habitat and interactions with other organisms.

What is the Competitive Exclusion Principle? No 2 SPECIES occupy exactly the SAME niche! Why? Competition!!

How do organisms interact in a community? Predation Competition Symbioses: –Parasitism –Mutualism –Commensalism

What is Predation? The predator captures, kills and consumes another organism, the prey. Predators have evolved adaptations to increase their efficiency at capturing prey, ex. Sharp teeth, camouflage, spider web Prey have also evolved defenses against predators, ex. Sharp thorns, Poisons, Mimicry-resemble a poisonous species

A decrease in the prey population means some predators will starve. Fewer predators mean prey population will increase. Increase in prey means more food for predators. Predator population will increase until there is not enough food and the cycle repeats itself.

What is Competition? Competition results from a niche overlap between 2 or more species. Competition for food, shelter, mates, space or light. Only one organism will use the resources more efficiently (and win) that will eventually eliminate the other species.

COMPETITION FOOD Organisms in an ecosystem have to compete with each other for available resources.

COMPETITION Organisms in an ecosystem have to compete with each other for available resources: shelter

COMPETITION Organisms in an ecosystem have to compete with each other for available resources mates

COMPETITION Organisms in an ecosystem have to compete with each other for available resources: space/territory Prairie dogs - 5 to 35 per acre Mountain lion- 1 male per sq. mi

COMPETITION Organisms in an ecosystem have to compete with each other for available resources: LIGHT

What are symbioses? Symbiosis= “living together” Close interaction (relationship) between 2 species living together –Parasitism –Mutualism –Commensalism

What is Parasitism? Involves a parasite that feeds off another organism, the host. Ex. Ticks, fleas, lice, leeches, tapeworms, malaria parasite, disease bacteria Parasites have evolved adaptations to exploit their host more efficiently

PARASITISM “Good for me - Hurts you” Tick feeds on dog’s blood; Dog has discomfort, can get diseases/infection from bite

PARASITISM “Good for me - Hurts you” Tapeworms absorb food by living inside host intestine; host is harmed

PARASITISM “Good for me - Hurts you” Barnacles are crustaceans that attach to the surface of whales and feed on their skin and fluids; Whale is harmed.

What is Mutualism? Mutualism is a cooperative relationship between 2 species in which both benefit. Neither can survive without the other. Ex. –Pollinators & Flowers –Birds & Rhinos –Clown fish & sea anemones

MUTUALISM “Good for me - Good for you” Insects transfer pollen between plants as they gather nectar for food.

MUTUALISM “Good for me - Good for you” Birds eat parasites living on the hides of giraffes and rhinos while enjoying protection from predators. Groomed animals lose their pests.

MUTUALISM “Good for me - Good for you” Clown fish gets protection from enemies by hiding out in poisonous sea anemones Sea anemone gets scraps of leftover food dropped by fish

What is Commensalism? Commensalism is an interaction in which one species benefits and the other is not affected. Ex. –Hermit crabs & snail shells –Pilot fish & sharks

COMMENSALISM “Good for me - Doesn’t bother you” Pilot fish receive scraps of food dropped by shark; Shark is neither harmed nor helped

COMMENSALISM “Good for me - Doesn’t bother you” Hermit crabs make homes in shells abandoned by snails; Snail is not harmed by crab

How do Organisms interact? Predation+ predator - prey Competition- Competitor 1 - Competitor 2 Parasitism+ parasite - host Mutualism+ Organism 1 + Organism 2 Commensalism+ Organism 1 0 Organism 2 SYMBIOSES + means “benefits” - means “harmed” 0 means “no affect”

ANY QUESTIONS?

Ecological Interactions Clock ? Clock ? #5: Create a VISUAL ILLUSTRATION explaining this information on p. 25 –Ex. Diagram, flow chart, concept map, etc. –Use the WHOLE page OR Clock ? #6: WRITE A LETTER/SHORT STORY explaining this information on p. 25 –Use the WHOLE page