Functional roles within communities

Question 1

3 types of key species with highest impact on community structure?

Answer 1

1. Dominant species
2. Keystone species
3. Foundation species (ecosystem engineers)

Question 2

Most abundant or have the highest biomass in a community?

Answer 2

Dominant species

Question 3

What causes a species to become dominant?

Answer 3

• dominant species more competitive at obtaining resources and more likely to win
• better at avoiding predation or disease

Question 4

Why are invasive species so successful?

Answer 4

Climate change causes them to relocate and are transported to different areas

Question 5

How do we measure impacts of dominant species on a community?

Answer 5

We remove it

Question 6

How to research species removal?

Answer 6

• Natural experiments
• Humans removing dominant species
• Mathematical modelling
• Microcosm experiments (Petri dishes)

Question 7

How do Keystone species get their name?

Answer 7

They lock whole structure into place, removal and community collapses. Not most abundant but strong control and how it interacts

Question 8

Origin of concept of keystone species

Answer 8

• 1960’s
• still relevant
• Robert Paine

Question 9

Removing the keystone species does what…?

Answer 9

Species richness falls rapidly

Question 10

Keystone predator =

Answer 10

Massive effect despite not being abundant

Question 11

What is an ecosystem engineer or foundation species?

Answer 11

Animals which physically alter their environment

Question 12

Example of ecosystem engineer

Answer 12

American beaver

Question 13

Example of keystone species

Answer 13

Sea otter

Question 14

What describes community organisation?

Answer 14

SImple models or the regulatory relationship between trophic levels

Question 15

What is meant by bottom-up control?

Answer 15

Communities only change in lower trophic levels
Increase in vegetation leads to more herbivores
Changes in nutrients drives trophic structure
Cascades up through food chain

Question 16

what is meant by top-down control?

Answer 16

Communities only change via changed in upper trophic levels
Changes in predator numbers effects lower trophic levels
Indirect effects from high level community to a lower level

Question 17

Bottom up and top down are extreme, what is normal?

Answer 17

Most communities interactions between trophic levels is reciprocal or direct of control may change over time and often can be both

Question 18

Ecosystems are influenced by what human management measures?

Answer 18

• Agricultural landscapes
• National parks
• Fisheries