Energy Flow and Keystone Species in Ecosystems, Module 9, Exam 3

Producers

Photoautotrophs that undergo photosynthesis and provide the energy and oxygen that supports all other trophic levels.

Primary production

The conversion of solar energy to chemical energy that is achieved via photoautotrophs via photosynthesis.

Primary consumers

Herbivores that consume producers.

Secondary consumers

Carnivores that consume herbivores.

Tertiary consumers

Carnivores that consume secondary consumers.

Quaternary consumers

Carnivores that consume tertiary consumers.

Decomposers

Mainly prokaryotes (like bacteria) and fungi. They secrete enzymes that digest molecules in organic material (often detritus or waste) and convert them into inorganic forms.

Trophic levels

The pattern of feeding relationships within an ecosystem.

Food chain

The sequence of food transfers up the trophic levels.

Keystone species

Species that have a disproportionately large effect on their environment relative to their abundance.

The type of ecosystem Bob Payne studied in the 1960's when he discovered keystone species.

Rocky intertidal ecosystems

What species came to dominate when Bob Payne removed starfish from the ecosystem?

Mussel populations

What happened to the ecosystems biodiversity when Bob Payne removed the starfish?

Biodiversity was reduced

What is the keystone species in the kelp forest ecosystem off the Aleutian Islands? What species do they prey upon, holding the balance of the ecosystem together?

Sea Otters that prey upon sea urchins that consume kelp forests.

Otters were exploited and over hunted for their fur during the 1800's. What effect did this have on the kelp forests in the Pacific Ocean off the western coast of North America?

Kelp forests were destroyed by the increased amount of sea urchins that were not being eaten by the sea otters. This led to a great loss of this marine ecosystem's biodiversity

Trophic cascade

A process that can occur if keystone species can be identified and returned to their natural abundance.

Extinction cascade

A process that occurs due to the loss of a keystone species in an ecosystem.

What is the keystone species that was reintroduced to Yellowstone National Park after an absence of 70 years? What effect did this have on the species composition of Yellowstone?

Gray Wolves. This resulted in a trophic cascade through the entire ecosystem by reducing elk populations.

Provide one example of a keystone species from the documentary "Serengeti Rules/Keystone Species Documentary"

Starfish

What species are the producers in marine ecosystems? What species are the producers in terrestrial ecosystems?

Phytoplankton (marine algae) and kelp are the producers in marine ecosystems. Plants are the producers in terrestrial ecosystems