Topic 14: Community- Structure and Dynamics

Question 1

What is a community?

Answer 1

A community is a group of interacting populations in a given location

Question 2

What is richness (S)?

Answer 2

the biological structure of a community is the mix of a species and their relative abundance

Question 3

What is the Simpsons diversity index (D)?

Answer 3

one way to help quantify the differences between community diversity and richness

Question 4

How are species organized by trophic level?

Answer 4

each link in the chain is considered a trophic level

Question 5

How are species organized by guilds?

Answer 5

acquire common resource/energy at the same trophic level

Question 6

What is bottom-up control?

Answer 6

productivity and abundance of populations at any given trophic level are controlled by the level below

Question 7

What is top-down control?

Answer 7

Predators control prey abundance and their behaviour

Question 8

What is trophic cascade?

Answer 8

one trophic level causes a powerful ripple of indirect interactions that can influence the entire community

Question 9

What is the organismal (holistic) approach? where does it work well?

Answer 9

focus is on how species have evolved together where interactions have shaped the specific community

works well in explaining communities that are easy to recognize as clusters of species that rise and fall together.

Question 10

What is the individualistic (continuum) concept? where does it work well?

Answer 10

focus is on individual species and how they respond to abiotic factors independently of each other

works well in explaining communities with unclear boundaries as communities overlap each other with borders that feel somewhat arbitrary.

Question 11

Where does primary succession occur?

Answer 11

occurs on new, previously unvegetated sites, no soil present.

Question 12

Where does secondary succession occur?

Answer 12

occurs on disturbed sites. environment is “prepared” and a soil present.