Community Ecology

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Number of species on island

(b) Effect of island size

Small island

Large island

Immigration

Immigration

(small island)

(large island)

Extinction

Extinction

(large island)

(small island)

(c) Effect of distance

from mainland

Number of species on island

Rate of immigration or extinction

Immigration

Immigration

(far island)

(near island)

Extinction

(far island)

Extinction

(near island)

Far island

Near island

Slide 51

Community ecology is useful for understanding pathogen life cycles and controlling human disease

Ecological communities are universally affected by pathogens, which include disease-causing microorganisms, viruses, viroids, and prions.

Pathogens can alter community structure quickly and extensively.

For example, coral reef communities are being decimated by white-band disease.

Slide 52

White-band disease on coral is destroying the reef.

Slide 53

Community Ecology and Zoonotic Diseases

Human activities are transporting pathogens around the world at unprecedented rates.

Community ecology is needed to help study and combat them.

Zoonotic pathogens have been transferred from other animals to humans.

The transfer of pathogens can be direct or through an intermediate species called a vector.

Many of today’s emerging human diseases are zoonotic. Avian flu is a highly contagious virus of birds.

Slide 54

Review

Slide 55

You should now be able to:

Distinguish between the following sets of terms: competition, predation, herbivory, symbiosis; fundamental and realized niche; cryptic and aposematic coloration; Batesian mimicry and Müllerian mimicry; parasitism, mutualism, and commensalism; endoparasites and ectoparasites; species richness and relative abundance; food chain and food web; primary and secondary succession.

Slide 56

Define an ecological niche and explain the competitive exclusion principle in terms of the niche concept.

Explain how dominant and keystone species exert strong control on community structure.

Distinguish between bottom-up and top-down community organization.

Describe and explain the intermediate disturbance hypothesis.

Slide 57

Explain why species richness declines along an equatorial-polar gradient.