Lecture 22

Question 1

What is stability in ecology?

Answer 1

• the ability of a biotic community to maintain its productivity and other functions as environmental conditions change
• also to recover former functions and species richness after a disturbance

Question 2

What are the 2 components of community stability and explain them a little

Answer 2

1. Resistance: the ability to minimize changes during a disturbance
2. Resilience: a measure of how quickly a community can recover following a disturbance

Question 3

WHat does high biodiversity do to community stability

Answer 3

• increases both resistance and resilience
• theoretically, many different species with partially overlapping niches can act as a “backup system” to maintain functions even if some species are lost through local extirpation, or even total extinction …

Question 4

explain the 4 stability model options

Answer 4

low resistance - low resilience: biomass decreases after disturbance and stays in disturbed state for long time

low resistance - high resilience: biomass decreases after disturbance and stays disturbed for a short amount of time and bounces back up quickly, restoring its state

high resistance - low resilience: biomass decreases slightly after disturbance and stays slightly disturbed for a long time

high resistance - high resilience: biomass slightly decreases after disturbance and stays disturbed for a short time before bouncing back up to its restored state (BEST OUTCOME)

Question 5

What are the 2 diff measures that are used to describe biodiversity in nature

Answer 5

• species richness
• species diversity

Question 6

how do you measure species richness

Answer 6

• a simple count of the number of specie sin a specific community

Question 7

how do you measure species diversity?

Answer 7

• a mathematical measure of richness combined with abundance of different species
• very high abundance of a few species, decreases the diversity
• high diversity includes high richness, plus a more even distribution of individual abundance among species
• numerical Shannon index of diversity is widely used (Higher number = Higher diversity)

Question 8

Where does biodiversity tend to increase?

Answer 8

• tend to increase towards the equator
• ex. amazon

Question 9

Why is there a greater diversity of life in the tropics?

Answer 9

many hypotheses but 2 most widely cited explanations:

1. high productivity hypothesis:
   - warm climate and low seasonality is reason tropics are more biodiverse
   - high productivity produces higher biomass and more niches that in turn increases herbivore diversity, followed by predators and other members of the community (but temperate rain forest is also very productive)
2. area and age hypothesis:
   - past glaciations have reduced diversity by disrupting ecosystems in northern regions
   - the more stable and larger areas of the tropics have had more time and space to accumulate new species by high speciation and low extinction rates

Question 10

What ist he modern climate between high plant and animal diversity environment and lower biodiversity

Answer 10

high plant and animal diversity: trophics- hot, equable year-round`

lower biodiversity: temperate zone-cool, seasonal changes in climate

Question 11

Review fossil record of insect diversity 53 mya (early eocene)

Answer 11

comparison of living and fossil insect diversity at:
1. harvard forest (cool temperate north america)
2. costa rica (tropical central america)
3. McAbee fossil beds in BC “okanagan highlands” (also include quilchena), warmer than today based on fossils

FINDINGS
1. as expected, modern insect diversity is low in temperate harvard forest, but very high in costa rica

2. the insect fossils of the temperate eocene okanagan highlands were more diverse than other modern temperate locations like harvard forest, and were richer in species, similar to modern costa rica
3. high climate equability (reduced seasonality) with low or no frost drove the high fossil biodiversity in the eocene highlands, rather than warm climates per se
4. as is usual, it is most likely that several factors have interacted to create the diversity patterns we see today

Question 12

Removal of “frozen organic muck” exposes what

Answer 12

fossils! and gold hehe

Question 13

What is the extinction of Megafauna linked to?

Answer 13

• linked to vegetation and climate changes
• 12-11000 ya
• probs due to hunting

Question 14

What are the 3 of many lessons learned frmo paleoecology and paleoclimatology?

Answer 14

• fossils can be used to record changes in past biodiversity, communities, and ecosystems
• climate change has been a driver of many ecological changes in geological time up to the present
• past changes can be a guide to potential future changes

Question 15

How do we know about past changes? explain using pollen and spore analysis

Answer 15

• abundant production by many plants well-dispersed by the wind in communities preserve well (both wet and dry conditions) readily identified microscopically

Question 16

heat, drought and fire promoted successional forests, which trees were restricted/promotied

Answer 16

• restricted Hemlocks and Red Cedar (fire-susceptible)
• promoted Douglas-Fir, Alder, Bracken (fire resistant)