Functional roles within communities

Question 1

Dominant species

Answer 1

Most abundant species or have highest biomass in a community
Exert strong ecological effect simply as a result of being highly abundant

Question 2

Keystone species

Answer 2

Exert strong control on community structure
Unlike dominant spec, they are not the most abundant species

Question 3

Ecosystem engineers or foundation species

Answer 3

Animals which physically alter their environment
Large herbivores often have large impact on the broader ecosystem

Question 4

What causes a species to become more dominant within a community?

Answer 4

2 main hypotheses
Dominant species more competitive at obtaining resources
Dominant species are better at avoiding predation or disease

Question 5

How to measure the impacts of a dominant species

Answer 5

By removing it
Dominant species removed - mixed effect on other species

Question 6

How to research species removal

Answer 6

Natural experiments
Humans removing dominant species
Mathematical modelling
Microcosm experiments

Question 7

Bottom-up control

Answer 7

Communities will change only via changes in lower trophic levels
Knowledge of Top-down and Bottom-up control allows us to solve ecological problems

Question 8

Top-down control

Answer 8

Communities will change only via changes in upper trophic levels
Knowledge of Top-down and Bottom-up control allows us to solve ecological problems

Question 10

In many communities the innteractions between trophic levels may be…

Answer 10

May be reciprocal
Or the direction of control may change over time, or with changing environmental conditions