Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Biology – Unit 2: Section 6 – Biodiversity
Biodiversity and endemism
Biodiversity is the variety of organisms






Biodiversity includes
o Species diversity
 The number of different species and its abundance in each area
o Genetic diversity
 The variation of alleles within a species
Conservation is needed to maintain diversity
Endemism is where a species is unique to a single place
An endemic species is really vulnerable to extinction and therefore conservation is important to them

Species diversity in a habitat can be measured







Important to measure species diversity in different habitats
You can measure species diversity in different ways
o Count the number of species in a different area
 This is the species richness
 Higher the number of species the greater the species richness
 Species richness gives no indication of the abundance of each species
o Count the number of different species and the number of individuals in each species
 Then using a biodiversity index e
...
Simpson’s index of Diversity to calculate the
species diversity
 Take into account the number and abundance of each species
This is usually time consuming to count every individual in a habitat
Instead a sample is taken and then estimates can be taken based on the sample
Sampling
o Choose an area to sample to avoid bias this should be random e
...
dividing a field into areas
and using a random number generator
o Count the number of individuals of each species in the sample area
 For plants use a quadrat
 For insects use a sweepnet
 For ground insects use a pitfall trap
 For aquatic animals use a net
o Repeat this using as many samples as possible
o Use the results to estimate the total number of individuals or total number of individual
species in the habitat
o When sampling different habitats use the same sampling technique

Genetic diversity within a species can also be measured







Diversity within a species is the variety shown by individuals of that species
Individuals in the same species vary because they have different alleles
Genetic diversity if the variety of alleles in the gene pool of a species
The gene pool is the complete set of alleles in a species
The greater the variety of alleles the greater the genetic diversity
To measure genetic diversity you can look at two things

1
...


Phenotype
 The observable characteristics of an organism, different alleles code for a different versions of
the same characteristics
 The larger the group of phenotypes the greater the genetic diversity
Genotype
 Sample of DNA can be taken and the base pairs are analysed, the order of bases in different
alleles is slightly different
 You can look at similarities and differences in the alleles within a species, you can measure the
number of different alleles a species had for one characteristic to see how genetically diverse the
species is
 The large the number of different alleles the greater the genetic diversity

Practise questions
1
...

3
...


What is biodiversity?
The variety of organisms within an area, this can include species diversity and genetic diversity
What is meant by species richness?
The number of different species in an area
What is meant by the term gene pool?
The complete set of alleles in a species
There are several species of finch that are only found on the Hawaiian islands
a
...
Describe one way you could measure the biodiversity of finches within a single habitat and
one way you could measure biodiversity within a single finch species
You could measure the biodiversity of finches using sampling and the biodiversity within a
single species using a method looking at the genotype of finches

Conservation of biodiversity
Zoos and seedbanks





Extinction of a species or a reduction in genetic diversity causes a reduction in global diversity
Some species are endangered
Conservation involves the protection and management of species
Zoos and seedbanks help to reserve endangered species

Seedbanks








Seedbanks store lots of seed from a range of plants
If the plant becomes endangered or extinct then there are seeds to grow more
They help to conserve genetic diversity by keeping a range of seeds from plants with different
characteristics
They create cool, dry conditions meaning the seeds can be stored for a long period of time
Advantages
o Cheaper to store seeds than fully grown plants
o Large numbers of seeds can be stored as they need less space than plants
o Less labour is required to look after seeds than plants
o Seeds can be stored anywhere as long as it’s cool and dry whereas plants need the right
environment which they have in the wild to grow
o Seeds are less likely to become damaged because of disease, natural disaster or vandalism
Disadvantages
o Testing the seeds for viability can be expensive and time consuming
o Too expensive to store all types of seeds and regularly test them
o May be difficult to get seeds from some plants as they are in remote areas

Zoos and captive breeding programmes



Species that are endangered or extinct in the wild can be bred together in zoos to increase their
numbers
Problems with captive breeding
o They can have trouble breeding outside their natural habitat which is hard to recreate in
zoos
o Can be cruel to keep animals in captivity

Reintroduction into the wild





Successful breeding and reintroduction into the wild can increase their numbers in the wild and
therefore help to conserve their numbers
This can help organisms further as they rely on the animals for food or plants for their habitat
Reintroduction also helps to restore habitats that have been lost
Reintroducing organisms to the wild can cause problems
o Could bring new disease to habitats, harming other organisms living there
o Animals bred in captivity may not behave the same as they would if they had been raised in
the wild

Scientific research


Seedbanks
o Can study how plants can be successfully grown from seeds, this can help to know how to
introduce them into the wild
o Can be used to grow plants to be used in medical research or new crops for new materials

o


Zoos
o
o
o

Only studying plants in seedbanks however can lead to limited data to a small amount of
interbred populations, data may not be representative
Increases knowledge of the behaviour, physiology and nutritional needs of animals, this
knowledge can be used to help animals in the wild
Can carry out research that is not possible for some species in the wild
Disadvantage is that captive animals may act differently to those in the wild and therefore it
may not be appropriate to generalise

Education people about conserving biodiversity




Help to raise public awareness and interest
Zoos let people get close to organisms therefore increasing their enthusiasm from conservation work
Seedbanks help by educating people by providing training and setting up local seedbanks –
Millennium Seed Bank Project

Practise questions
1
...


3
...
Captive breeding and reintroduction programmes
are being used to increase their numbers in the wild
...

One problem is that you may introduce new diseases to habitats, which harms other organisms living
there
...
Another problem is it’s hard to recreate the
animals natural habitat in the wild in a captive centre, meaning there is less chance of the animals
breeding
...




---