C6. Biodiversity

Question 1

Terms you need to know
Before you can sink your teeth into the real meat of biodiversity, there are a few definitions you need to know:

Biodiversity?
Habitat?
Community?

Answer 1

Biodiversity is the variety of living organisms in an area.

A habitat is the place where an organism lives, e.g. a rocky shore or field.

A community is all the populations of different species in a habitat.

Question 2

Levels of biodiversity
Biodiversity can be considered at a range of scales from the local to
the global: (talk about both)

Answer 2

Local biodiversity - you could consider the variety of different species living in a small habitat that’s local to you, e.g. a pond or meadow, or even your back garden. Some habitats will be more biodiverse than others.

Global biodiversity - you could also consider the variety of species on Earth. Recent estimates put the total number of species on Earth at about 8.7 million. Biodiversity varies in different parts of the world- it is greatest at the equator and decreases towards the poles.

Question 3

Measuring biodiversity

Biodiversity can be measured using … or an …

Species richness is …-which makes it a simple measure of biodiversity. It can be worked out by taking ________ __________ of a community and counting the number of different species.

However, the number of different species in a community isn’t the only thing that affects biodiversity. The ___________ ______of those species do too. Species that are in a community in very small numbers shouldn’t be treated the same as those with _________ populations. This is where an index of diversity comes in.

An index of diversity is another way of measuring __________. It’s calculated using an equation that takes both … into account.
You can calculate an index of diversity (d) using this formula:

Answer 3

Biodiversity can be measured using species richness or an index of diversity.

Species richness is a measure of the number of different species in a community-which makes it a simple measure of biodiversity. It can be worked out by taking random samples of a community and counting the number of different species.

However, the number of different species in a community isn’t the only thing that affects biodiversity. The population sizes of those species do too. Species that are in a community in very small numbers shouldn’t be treated the same as those with bigger populations. This is where an index of diversity comes in.

An index of diversity is another way of measuring biodiversity. It’s calculated using an equation that takes both the number of species in a community (species richness) and the abundance of each species (population sizes) into account.

You can calculate an index of diversity (d) using this formula:
d = N(N-1)/ Σn(n-1)

Where…
N = Total number of organisms of all species
n= Total number of organisms of one species
Σ= ‘Sum of (i.e. added together)

Question 4

Tip: The number of species in a community and the abundance of each species is also known as the …

Answer 4

Tip: The number of species in a community and the abundance of each species is also known as the species diversity.