Symbiosis Review

Relationships in Ecosystems

• There are many ways that organisms interact with each other within ecosystems

• We have previously studied food webs as a way to map the flow of energy through an ecosystem from the sun to top consumers and back to producers again

• There are more complex relationships that we will explore next

Symbiosis

• Symbiosis describes any long-term relationship between two organisms from different species

• These relationships usually benefit one organism• The other organism may

– 1) benefit as well (mutualism)– 2) be harmed by the relationship (parasitism)– 3) neither benefit nor be harmed by the relationship

(commensalism)

Mutualism

• Mutualism describes a type of long-term relationship between two organisms in which BOTH organisms benefit

• Example:– Clownfish and sea anemones

• Who benefits? Who is harmed?– Bird eating ticks off of cow

• Who benefits? Who is harmed?

Commensalism

• Commensalism describes a type of long-term relationship between two organisms in which one organism benefits, and the other is unaffected

• Example:– Remora hitching a ride on a shark

• Who benefits? Who is harmed?

Parasitism

• Parasitism describes a type of long-term relationship between two organisms in which one organism benefits, and the other is harmed

• Example:– Parasitic fish “lice”

• Who benefits? Who is harmed?

7

What is ammensalism?

• Ammensalism is the ecological interaction in which an individual species harms another without obtaining benefit.

• This type of symbiotic relationship is common, but not considered an important process structuring communities because they are “accidental” and do not benefit the species doing the harm

• It is a 0/- relationship

Examples of Ammensalism• Elephants stepping on ants or leveling

brush does not benefit the elephant but causes harm

Examples of Ammensalism• Algal blooms can lead to the death of many

species of fish and other animals, however the algae do not benefit from the deaths of these individuals

Examples of Ammensalism• One of the best examples of ammensalism is

the one established between humans and other species under extinction due to human actions like habitat devastation by fires, ecological accidents, pollution of water, etc.

Examples of Ammensalism• One way scientists have used ammensalism

to help humans can be found in the relationship of the bread mold penicillium with bacteria. Penicillium releases a chemical called penicillin which kills bacteria without benefiting the bread mold. Luckily we use this secretion as medicine!

Unfortunately science is slow• Rheumatic heart disease is a chronic (long-term) heart condition

caused by rheumatic fever• Rheumatic fever is caused by a preceding group A streptococcal

(strep) infection• Treating strep throat with antibiotics can prevent rheumatic fever• Moreover, regular antibiotics (usually monthly injections) can

prevent patients with rheumatic fever from contracting further strep infections and causing progression of valve damage.

• Rheumatic heart disease is known as a disease of poor people because it leads to 15 million or more cases of heart disease that requires open heart surgery, all in areas where antibiotics are unavailable

Influence of species A

Influ

ence

of S

peci

es B

+ (positive)0 (neutral/null)- (negative)

A B

Amensalism

0

-

A B

Commensalism

+

0

A B

Commensalism

0

+A B

Mutualism

+

+

A B

Amensalism

-

0

A B

Parasitism

-

+

-

0

+

A Summary of Symbiotic Interactions

A B

Parasitism

+

-A B

Mutualism

+

+

Class Review

• Split into four groups, each with a different colored marker

• You will rotate as the star board displays a different task

• Each group will begin at a different type of symbiosis (please label all four)

Class Review

• Task 1: What is the definition of your group’s type of symbiosis?

• Task 2: What is an example (without explanation) of your group’s type of symbiosis

• Task 3: Explain the example given by the previous group

• Task 4: What is a second example WITH explanation of your group’s type of symbiosis?

Review game

• Ring toss game• Four teams• You will answer questions as a team• If you get the answer correct

– Your team receives 1 point– Your team may choose one person to throw for bonus

points• If a team gets a question incorrect, the other

team may steal

For the quiz

• Be prepared to answer 4 open ended questions that require:

• Identification of which species benefits/harmed/neither for any situation

• Identification of which type of symbiosis is observed supported by evidence

• Prediction of changes in population if the population of one species from a symbiotic relationship is altered

• Review the study guides on the class page