L11 - Biodiversity theories

Question 1

Why is biodiversity important?

Answer 1

Genetic diversity, recovery from disaster, protect freshwater resources, maintain food chain, adaptation

Question 2

Genetic diversity

Answer 2

the biological variation that occurs in species. Makes adaptation possible

Question 3

Species diversity

Answer 3

The number of species present in an ecosystem and relative abundance of each.
Measured by richness (number) and evenness (abundance)

Question 4

Ecosystem diversity

Answer 4

encompasses all ecosystems and habitats as well as essential services

Question 5

Evenness

Answer 5

distribution of the number of individuals over the number of species compared to the situation where H would be maximal

Question 6

Where on Earth is the greatest species richness?

Answer 6

The tropics, specifically the Amazon

Question 7

Why are the tropics rich in biodiversity?

Answer 7

1. More solar energy - higher productivity and diversity
2. High rainfall - supports primary production
3. Less seasonal variation - promotes specialisation and richness
4. Undisturbed by glaciations
5. Resource rich

Question 8

When you increase search area you find more species, but this levels off after a certain point. Why?

Answer 8

Due to the species area relationship - sampling bias, species distribution patterns (localised ranges), habitat heterogeneity, diminishing returns

Question 9

OCBIL theory

Answer 9

= old, climatically buffered, infertile, landscapes theory
- Stable over long time scales
Enough time for diversification in response to competition for the same scarce resource

Question 10

When were the highest seas?

Answer 10

90 Ma

Question 11

Species energy theory (Wright 1983)

Answer 11

a large amount of resources relaxes competition, allowing more species to co-exist. An increase in population reduces risk of random extinction

Question 12

What does energy availability regulate?

Answer 12

Population size, extinction rates and species richness

Question 13

Multidimensional niche hypothesis

Answer 13

the number of added resources remained a significant predictor of diversity loss. Resource supply could cause changes in competitive dominance and lead to species exclusion

Question 14

Biodiversity ecosystem functioning theory

Answer 14

productivity is not the driver of species diversity, but the result. More species means more efficient and complete use of all available resources, thus higher productivity

Question 15

Is productivity a good predictor of plant species richness?

Answer 15

No

Question 16

Threats to biodiversity?

Answer 16

1. Land and sea use change
2. Pollution
3. Species overexploitation
4. Climate change
5. Invasive species and disease

Question 17

Intermediate disturbance hypothesis

Answer 17

• High disturbance = pioneer species (low diversity)
• Low disturbance = climax species (low diversity)
• Intermediate disturbance = support both species that require disturbance to propagate and species that persist through disturbance (high diversity)