RELATIONSHIPSBetween Organisms:

Ecological Interactions: Symbiosis

What are some ecological groups?

▪ Population – group of individuals of the same species

▪ living in the same area, potentially interacting

▪ Community – group of populations of different species

▪ living in the same area, potentially interacting

What is symbiosis?

▪What it means:

•Two organisms that live together

•Temporarily or for a longer time

•At least one of the organisms benefits from the relationship

Literal definition: the act of living together

Why are ecological interactions important?

▪ Interactions can affect distribution and abundance (amount).

▪ Interactions can influence evolution.

How the following interactions can affect

distribution, abundance, and evolution?

Types of ecological interactions: All relationships can benefit, harm or not

affect the chance of another organisms survival.

1) Mutualism – two species provide resources or services to each other

enhances fitness of both species

Mutualism Example A

Antelope gets rid of parasites

Oxbird gets a meal

Mutualism Example B:

▪Moray Eel gets a clean mouth Cleaner Fish gets a meal

Here are three other examples of mutualistic relationships:

C. The bee and the flower. This benefits the plants. In this relationship, the bees get to eat, and the flowering plants get to reproduce.

D. The spider crab and the algae. The algae gets a good place to live, and the crab gets camouflage.

E. The bacteria and the human. The bacteria benefit by getting food, and the human benefits by being able to digest the food it eats.

2) Commensalism – one species receives a benefit from another species enhances fitness of one species; no effect on fitness of the other species

A) Cattle and Egrets: Cattle stir up insects as they eat grass. Egrets hang around and eat insects

B) Remora Sharks: They “Hitch” a ride on larger animals and gather food along the way.

Commensalism Examples:

Other examples of commensalistic relationships:

C. Barnacles adhering to the skin of a whale : The barnacle benefits by filtering food as the whale swims. Its does not seem to affect the whale.

D. Sea Anemone and Clownfish: Clown fish gets protection Anemone is unaffected

http://www.youtube.com/watch?v=eWXOurnVTYg

E. Birds and Trees: Birds build nests in

trees.

3) Predation – one species feeds on another Enhances fitness of predator but reduces fitness of prey

herbivory is a form ofpredation

A) Cattle and grass: Cows eat and kill the grass for food.

B) Wolf and Deer: Wolf kills and eats deer for food

C) Baleen Whale and plankton: Whale filters plankton from water as it swims.

Predation Examples:

D) Lynx and Snowshoe Hare: As you can see by the graph, their populations are directly linked.

4) Parasitism – one species feeds on another Enhances fitness of parasite but reduces fitness of host. It is in the parasite’s best interest not to kill the host.

Parasitism Examples:

A) Ants and Acacia Tree: lay eggs on acacia tree, Acacia covers the infected area with brown flesh (gall)

B) Tapeworm and Cow: They get food by eating the host's partly digested food, depriving the host of nutrients.

C) Fleas and Cats: fleas bite the Cats skin, sucking their blood, and causing them to itch and possible get sick. The fleas, in turn, get food and a warm home.

Parasitism

D) Wasp eggs on back of caterpillar.

F) Mosquito biting a human.

E) Sea lampreys feed on fluids of other fish.

5) Competition – two species share a limited resource reduces fitness of one or both species

Here are three examples of competition relationships:

A. Spruce and Pine Tree: They must compete for light, water and nutrients.B. Cheetahs and Lions. They must compete for the same prey such as zebras.C. Coyotes and bobcats: They compete for the same prey such as rabbits.

competition relationships continued:

D. Hyenas and Lions in Africa: fight over gazelle

E. Rams: compete with each other for mates.

F. Gray Squirrels and Red Squirrels: Until Americans introduced gray squirrels into parts of England in the early 20th century, red squirrels had been the only species of squirrel in the country. The gray squirrels were larger and bred faster and successfully competed for resources. Within a couple years of overlap in an area, the red squirrels disappeared.

6) Amensalism is a relationship in which a product of one organism has a negative effect on another organism.

▪ A) Penicillium and bacteria: penicillium secretes penicillin, a chemical that kills bacteria.

▪ B) Black Walnut Tree and other plants: The Black Walnut gives off a chemical that harms or kills some species of neighboring plants.

▪ C) Sheep and grass: Sheep make trails by trampling on thereby destroying a food source.

7) Neutralism: describes the relationship between two species which interact but do not affect each other.▪ Neutralism describes interactions where the fitness of one

species has absolutely no effect whatsoever on that of the other.

▪ True neutralism is extremely unlikely or even impossible to prove.

▪ When dealing with the complex networks of interactions presented by ecosystems, one cannot assert positively that there is absolutely no competition between or benefit to either species.

▪ Since true neutralism is rare or nonexistent, its usage is often extended to situations where interactions are merely insignificant or negligible.