Food webs 2: commmunity ecology and interaction networks

Question 1

What is ecological network analysis?

Answer 1

Study of ecological systems using network models and analysis to characterize their structure, function and evolution

Question 2

What does a node represent in ecological systems?

Answer 2

individual species or population or functional group

Question 3

What do links represent in ecological systems?

Answer 3

Interactions between nodes

Question 4

What are three ways of characterizing links?

Answer 4

1) Topology: how are links arranged
2) Geometry: includes distance between nodes, therefore the importance of the interaction
3) Direction and stregth: differentiates interactions

Question 5

What are different types of interaction?

Answer 5

1) Presence/absence
2) directed networks
3) interaction sign (+ or -)
4) Weighted networks: strength assigned to links

Question 6

What is defined by the number of nodes in the foodweb?

Answer 6

Species richness

Question 7

What defines network complexity?

Answer 7

Connectance and linkage density

Question 8

What is the ‘proportion of directed links realized out of the maximum number of possible links’ called?

Answer 8

Connectance

Question 9

What is the ‘number of trophic interactions’ called?

Answer 9

Linkage density

Question 10

What is the ‘count of number of interactions established by a species’ called?

Answer 10

Degree centrality

Question 11

What does mean shortest path define in a network?

Answer 11

Stability, shorter chain is more stable

Question 12

What is vulnerability?

Answer 12

Number of consumers

Question 13

What is ‘number of resources per taxa’ called?

Answer 13

Generality

Question 14

What do trophic levels represent?

Answer 14

Energy steps that are taken to reach higher up in the food web

Question 15

What is omnivory?

Answer 15

Variability in trophic levels of preys

Question 16

What is degree distribution?

Answer 16

Defines variability of linkage density and how equally distributed connections are in the system

Question 17

How is a centralized network organized?

Answer 17

Has high degree distribution, with few central nodes with many connections and others with few

Question 18

What term describes the extent to which the network can be divided into non-overlapping grups of highly interacting species within their local neighborhood?

Answer 18

Modularity

Question 19

What are the components of node-weighted dynamics?

Answer 19

Connectance, vulnerability, generality, trophic level

Question 20

What does ‘node-weighted’ mean?

Answer 20

Averaged/weighted by biomass

Question 21

What is a keystone species?

Answer 21

A species with high centrality in the ecosystem

Question 22

What is the keystone index?

Answer 22

Indicates how fundamental their role is in the ecosystem as compared to their number

Question 23

What is ecological resilience?

Answer 23

The amount of disturbance that a system can withstand without changing into an alternate stable state

Question 24

What is engineering resilience?

Answer 24

Time required for the system to come back to equilibrium or steady state after the system has been perturbed

Question 25

How is a ‘state’ defined?

Answer 25

COmbination of function, structure, identity and feedbacks

Question 26

What characterizes most resilient foodwebs?

Answer 26

Abundant weak links and high diversity

Question 27

What is network robustness used for?

Answer 27

Measure food web resilience. Measures potential impacts of extiction on food webs and proposes an index of resilience

Question 28

What is the System Omnivory Index?

Answer 28

Index that quantifies the interactions among the trophic levels. High omnivory increases resilience

Question 29

What determines a major role in pattern and strength of trophic interactions within the foodweb?

Answer 29

Body size

Question 30

How does climate change impact marine food webs?

Answer 30

Biogeographic shift
Body size
Phenological shift (nature clock)
Average sea level rise