Topic 25 -Biodiversity

Question 1

Ability of a community to either resist change or rebound to its original state are critical to

Answer 1

maintain biological structure under changing environmental conditions

Question 2

Stability (Resistance)

Answer 2

ability to resist change in biological structure (maintain a relative constant state) under environmental change

Question 3

Resilience

Answer 3

speed and ability to return to its original structure after environmental change

Question 4

community stability/resilience is linked to

Answer 4

food web complexity

Question 5

Linkage density

Answer 5

average number of actual links (arrows) per species in a food web

Question 6

Connectance

Answer 6

number of links divided by the number of possible links

Question 7

Food chain length

Answer 7

number of trophic levels (most have 4)

Question 8

Food web complexity is defined by

Answer 8

a combination of food chain length, species richness, linkage density, connectance

Question 9

general pattern for food web complexity

Answer 9

higher food web complexity (species richness) -> higher community “stability” (resistance to change)

but more complex food webs have lower “resilience”
if the structure of the food web changes it will take longer and harder to return to original state

Question 10

Two conceptual models for removal of weak interactor

Answer 10

Redundancy Model

Rivet Model

Question 11

Redundancy Model

Answer 11

species=passengers on a plane
loss of important passenger (plane doesn’t fly) -Dominance effect
implies: species within functional groups are redundant

Question 12

Rivet Model

Answer 12

species= rivets on a plane
loss of many rivets ->plane falls apart -complementary effect
implies all species in functional group is important

Question 13

Diversity-Stability (insurance) Hypothesis

Answer 13

species richness provides insurance and buffers or minimizes chances of changes in structure under environmental change

Question 14

Response diversity

Answer 14

variation in responses to environmental change among species within functional group

Question 15

why is response diversity critical

Answer 15

because species will respond differently to environmental change, these different responses will maintain community structure in its original state

Question 16

Coral/Algal phase shift

Answer 16

free-living algal species will readily outcompete coral species if left unchecked
in coral dominated communities several herbivores exist that consume algae
as herbivores are removed from the community response diversity is eroded
at some point community becomes particularly prone to irregular changes in environmental conditions