11.6 Factors Affecting Biodiversity

Question 1

Factors that affect GBD

Answer 1

Alleles can occur through:

MUTATIONS, in the DNA of an organism creating a new allele.
Interbreeding between different populations. When an individual migrates between different popns. and breeds, alleles are transferred between populations (GENE FLOW).

In order for GBD to decrease, the number of possible alleles in a popn. must also decrease through:
1. selective breeding (artificial selection), where only a couple in a popn. are selected for advantageous characteristics and bred.

2. Captive breeding programmes in zoos, for example.
3. rare breeds where selective breeding (SB) has been historically used to produce a breed of domestic animal or plant with characteristics which become less popular.
4. artificial cloning (asexual)
5. NATURAL SELECTION - as a result, species will evolve to contain advantageous alleles.
6. GENETIC BOTTLENECKS where few individuals within a popn. survive an event or change, thus reducing the ‘gene pool’.
7. the FOUNDER EFFECT, small number of individuals create a new colony, geographically isolated from the original.
8. genetic drift, due to a random number of alleles being passed on from parents to their offspring.

Question 2

Human Influence on BD

Answer 2

Human popn. is increasing. To create enough space for housing, industry and farming for humans, it’s disrupting the ecology of many areas. Main problems arising:

1. deforestation
2. agriculture
3. climate change

Question 3

Deforestation

Answer 3

Can happen deliberately or indirectly. Affects BD by:

1. reduces number of trees
2. if only a specific type of tree is felled, the species diversity would decrease.
3. reduces no. of animal species if their habitat is destroyed.
4. animals are forced to migrate to other areas.

Question 4

Agriculture

Answer 4

Farmers often select the crops that give the most yield so, overall diversity is often low.
In order to be economically viable, once the farmers have selected their desired species, a no. of techniques are used the produce lots of the desired product.

However, these techniques lead to lack of diversity:

1. deforestation
2. removal of hedgerows
3. use of chemicals such as pesticides or herbicides
4. herbicides are used to kill weeds
5. monoculture ( farmers specialise in growing only 1 crop)

Question 5

Climate Change

Answer 5

Some of the key findings from a report:

1. warming trend over last 50 years.
2. average amount of water vapour in the atmosphere has increased.
3. Since 1961, average temp of global ocean down to depths of 3km has increased.
4. the global average sea level rose by an average of 1.88mm per year.
5. average Arctic temps increased
6. ice caps have melted.

Question 6

Climate Change Prevention Measures

Answer 6

The need for reliable data is now even more important because of the impact CC is having on communities. If global warming continues, BD will be affected by:

1. the melting of the ice caps could lead to extinction of species in these regions.
2. rising sea levels from melting ice caps could flood land.
3. higher temps and less rainfall would result in some plant species dying out, leading to drought-resistant species being more dominant.
4. insect life cycles and populations will change as they adapt to climate change. Insects are key pollinators so it would also affect plants. And as insects carry many plant and animal pathogens, if tropical insects spread, it could lead to widespread diseases.