3.1 An introduction to biodiversity

Question 1

What is the definition of “biodiversity”?

Answer 1

The amount of biological or living diversity per unit area. It includes the concepts of species, habitat and genetic diversity.
(The variety of living organisms in an area)

Question 2

What does biodiversity lead to?

Answer 2

Biodiversity leads to stability and resistance to change. It provides us with resources and ecosystem services.

Question 3

What are some characteristics of ecosystems with low biodiversity?

Answer 3

• very low precipitation
• small nutrient cycle
• high daytime temperature (fluctuates heavily at night)
• few species can withstand these extreme conditions

Question 4

What is “habitat diversity”?

Answer 4

Range of different habitats in an ecosystem or biome

Question 5

What are the two main ways in which biological diversity is quantified?

Answer 5

• Richness
• Evenness

Question 6

What is the definition of “richness”?

Answer 6

Refers to how many species are present in a habitat. The more there are, the richer the habitat.

Question 7

What is the definition of “evenness”?

Answer 7

Measure of the relative abundance of the different species.
If the species have a similar abundance, then there is high evenness.

Question 8

What is “endemism”?

Answer 8

Describes the situation where a species of organism is only found within a particular area.
This happens because the organism evolved within that region and hasn’t migrated out to other areas.

Question 9

When does “endemism” occur?

Answer 9

Physical barriers (oceans and mountains) which limit migration.
Islands are likely to have more endemics.

Question 10

What are “biodiversity” hotspots?

Answer 10

Describes areas of particularly high biodiversity and endemism.

Question 11

What are some examples of criticism towards the “hotspot approach”?

Answer 11

• main focus is plants not animals
• do not represent total diversity or richness
• emphasis is on areas where habitat is already lost not where it is at risk
• does not take genetic diversity into account
• does not consider value of ecological services provided

Question 12

What are “keystone” species?

Answer 12

A keystone species is a species which has a disproportionately large effect on its natural environment relative to its abundance.
eg. beaver