L1 - Conserving dwindling biodiversity

Question 1

What has become a dominant argument for the conservation of biodiversity, especially in politics?

Describe an important review of this

What task must therefore be taken to protect biodiversity?

Answer 1

• The converted economic value of biodiversity

The Dasgupta Review:
- economy depends on nature, rather than being separated

• Need to map biodiversity and track it’s change

Question 2

Describe the two most basic approaches to species range mapping

Describe the downsides to each one

Evaluate when and why they are useful

Answer 2

Extent of Occurrence (EOO):
- Draw the minimum convex hull around data of known locations
- Can vary significantly with outliers (see diagram in notes)

Area of Occupancy (AOO):
- Create grid + count no. of pixels containing points
- Depends heavily on pixel size

• Both crude but straightforward + easily replicable, don’t require large data needed for statistical models

Question 3

How are EOO and AOO models used by international conservation organisations?

Answer 3

International Union for Conservation of Nature (IUCN) use these
- Loss of species range size calculated by superimposing land-use change maps onto range maps
- Species then classed into threat status
- “Red lists” used by governments for decisions e.g. protection of Cod in 90s
- Regions with high frequency of endangered organisms identified

Question 4

What is the alternative, often more sophisticated, way to map species range? Describe how these are made

What limits the widespread use of this?

Answer 4

Statistical model distributions
- Presence and absence species data paired w/ environmental data to produce predicted probability of occurrence via logistic regression

• Makes better range maps than EOO + AOO of >15 records available (environmental records?)
• Not widely used by IUCN as often < 15 data records

Question 5

What impact are humans having on species extinction rates?

Answer 5

Millennium Ecosystem Assessment showed increased rate of extinction set to accelerate
- Current rate surprisingly low at 0.01% species per year but still 1000 times higher than in fossil record
- Far higher no. with threatened extinction

Question 6

What explains the trend of very increased no. of threatened species but relatively lower extinction rate?

Sketch a graph of area sampled against species sampled

Give evidence for this relationship

Answer 6

Species-Area Relationship (SARs) crucial:

No. species = b (Area Sampled)^z
(z<1, typically 0.25)

So percentage extinction rates = 1/4 (percentage habitat loss)

E.g. Simberloff’s Experiments of reducing mangroves with chainsaw + monitoring invertebrate diversity

Question 7

Sketch a graph of persistence probability vs percent habitat remaining for multiple rarities of plant + describe

Answer 7

• Widespread plants have high persistence probability until very little habitat remaining
• Rarer plants decrease much more rapidly

Question 8

Give a reason why even SAR models often over-estimate extinction rates in the short term?

What’s the implication of this all?

Answer 8

Population may be destined for extinction but slowly dwindles

Nature is resilient but potential extinction crisis looming as land use hits critically low values

Question 9

Give 4 main points to outline how human impact can be reduced

Answer 9

1) Identify priority areas
- Biodiversity hotspots identified
- Different criteria possible e.g. high endemicity + high habitat loss

2) Government commitments to biodiversity conservation
- E.g. COP15 established 30% of land and oceans protected by 2030

3) Developing networks of protected areas
- E.g. create corridors

4) Ensure organisms are properly protected in these areas