THE NATURE OF ECOLOGY

Ecology is a study of connections in nature.– How organisms

interact with one another and with their nonliving environment.

Figure 3-2

 Ecologists recognize 5 major kinds of species interactions

in communities:Predation, Mutualism,

Commensalism, Competition, or Parasitism

Symbiosis

A symbiosis is a close, long term relationship between two organisms.– Commensalism– Parasitism– Mutualism

Commensalism

Commensalism is a relationship between two living organisms where one benefits and the other is neither harmed nor helped.

The clownfish lives among the forest of tentacles of an anemone and is protected from potential predators.

Some birds live among cattle to eat the insects stirred up as they walk. One

example are egrets who hunt for insects near a grazing animal's mouth.

One animal attaching itself to another for transportation such as barnacles

attach to shells or whales; or a shrimp riding on a sea slugs.

barnacles on whale’s tail and clam shrimp riding on a sea slug

One species uses a second organism for housing such as small mammals or birds that lives in holes in trees or orchids which live in trees.

Orchid in rainforest Venezuela

Parasitism

One organism, usually physically smaller of the two (the parasite) benefits and the other (the host) is harmed

Ticks and fleas that live in a host animal's fur bite the animal and drink its blood are parasites.

Insects such as mosquitoes feeding on a host are parasites.

Vines such as Kudzu growing on Trees

Tomato Hornworm with Wasp Eggs

Tapeworm or Hookworms living in Host's Gut

The roots of the Owl Clover are partly parasitic on the roots of other

desert wildflowers.

Mutualism

Both species benefit from the interaction.

Flowers and their Pollinators (examples:  Bees and

hummingbirds gather nectar and spread pollen.)

Birds and mammals eat berries and fruits while the plant benefits by the

dispersal of it seeds.

Algae and Fungi > Lichen - Alga gets water and nutrients from the fungus and the fungus gets food

from the algae.

Cleaners eat insect pests from the skin of animals. (ex: Egyptian plover cleans

giraffes and buffaloes)

Many herbivores such as cows, sheep, deer, horses and rabbits depend on bacteria that live in their stomachs to

break down the plant material.

Coral Reefs- The corals get food and the algae get protection.

Predation

one eats another (Herbivores eat plants. Carnivores eats animals.)

Competition

Competition may cause competitive exclusion, the elimination of one species in a community.

Competition also drives the evolution of a community.