Genetic Diversity, Adaptation and Biodiversity (copy) (copy)

population

all the organisms of one species that live in a habitat

gene pool

all the alleles in a population

species

group of organisms that are able to produce fertile offspring

Suggest and explain one reason why successful reproduction between Ulva prolifera and Ulva lactuca does not happen

They are different species

• therefore if they fused together they would not produce fertile offspring

community

the organisms of all the different species that live in one habitat, and interact with each other

species richness and how can it be determined

the number of different species in a community

1. use random number generator to select sampling site at random

2. use quadrats

3. count number of different plant species in each quadrat

method to determine the total number of the beetle species in the meadow

• determine the area of plot 1

• calculate the total area of the meadow

• divide the area of the meadow by the area of the plot

• multiply by the number of beetles

What is the difference b/w species richness and an index of diversity?

Species richness only measures the number of different species, it does not measure the number of individuals

give 2 ways that the students would have ensured their index of diversity was representative of each habitat

• random samples

• large samples

suggest how to get a more precise value for the index of diversity for a habitat

• take more samples and find mean

• use a random number generator to pick coordinates and collect species data at those points

The index of diversity of the insects was higher in the hedge than in the barley field. Explain why.

• more plant species

• more food sources

• more habitats

what is biodiversity and how can it be measured?

The variety of living organisms

It can be measured in terms of:

- species diversity (number of species in a community)

- ecosystem diversity (range of different habitats)

- genetic diversity

What is global biodiversity?

the variety of species on earth

What is local biodiversity?

the variety of species living in a (small) habitat close by

- e.g. a pond or woodland

What is ecosystem diversity?

The range of different habitats in an area

abiotic factors

non-living factors

What advantage does a high genetic diversity provide?

ability to adapt to change in environment

• allows natural selection to occur

Directional selection

• individuals with certain advantageous alleles more likely to survive and reproduce and pass on advantageous allele to offspring

• Therefore frequency of advantageous allele increases

Stabilising selection

Organisms less likely to survive at the extreme

• more likely to survive from the middle of the range

• The mean (wtvr mentioned in question e.g. birth mass) is favoured

• Bell shaped curve

• e.g babies with extreme birth mass less likely to survive and pass on their alleles

• Extreme mass at birth decreases in frequency

How can genetic diversity of a population be increased?

1. Mutation of DNA, causing new alleles to be formed

2. New alleles can be introduced if a new population of that species migrates to the area (gene flow)

niche

the role of a species within its environment

• species sharing the same niche will compete with each other

how could you determine if two organisms from different populations belongs to the same species

breed together

• if fertile offspring: then same species

What is traditional taxonomy and its limitations?

The comparison of the frequency of observable characteristics

- limited by polygenic (coded for by more than one gene) features and environmental effects

How are organisms compared in modern taxonomy?

Through the similarities/differences of their:

1. DNA base sequences

2. mRNA base sequences

3. Amino acid sequences

Explain how scientists may have used DNA sequencing to determine the evolutionary relationship between hyrax and elephant

• Isolate and sequence DNA from both species

• Compare select regions of DNA

• The more similar the DNA base sequence, the more closely related the organisms are

classification

The process of arranging organisms into groups

What is artificial classification?

Division of organisms based on obvious differences (e.g. colour,size etc.)

Can be based on analogous characteristics

Explain what is meant by a heirarchy/hierarchical classification

1. Groups within groups;

2. No overlap (between groups);

Describe Domain Eukarya

1. Mainly multicellular

2. Cells contain membrane-bound organelles

3. Membranes contain fatty acids linked to glycerol via ester binds

4. 80S ribosomes

5. Cell walls made of chitin/cellulose

Describe Domain Archaea

1. Genes similar to eukaryotes

2. No murein in cell walls

3. More complex RNA polymerase

4. 70S ribosomes

Describe Domain Bacteria

1. Unicellular

2. Murein cell walls

3 no membrane-bound organelles

4. 70S ribosomes

5. Single loop of DNA, but no histones

how are phylogenetic groups created

Grouped according to evolutionary links and common ancestry

What impact does agriculture have on species diversity?

decreases species richness

• farmland is typically used for only 1 species (monoculture)

• use of pesticides/ herbicides

List 5 agricultural practices that reduce biodiversity

1. Removing hedgerows

2. Clearing large woodlands

3. Use of pesticides

4. Use of herbicides

5. Monoculture

How does monoculture reduce biodiversity?

Monoculture means growing only one type of plant, so other plants that are natural to the area are killed and removed to make space

Fewer organisms can be supported

How does the use of herbicides reduce biodiversity?

1. Plants are killed - biodiversity is reduced

2. Species that prey on these plants lose their food resources

• so their species number could also fall

How does the use of pesticides reduce biodiversity?

1. Pesticides are chemicals used to kill the organisms that feed on crops

• so the pests are killed, biodiversity is reduced

2. Species that prey on the pests lose food sources

• so species numbers could also fall

How does the clearing of woodlands reduce biodiversity?

1. The number of trees, and the number of species of trees are both damaged

• this means that habitats are destroyed

2. The land is used for farming, so the species living there cannot use it for shelter or as a food source (esp. if pesticides are used)

• so the species must migrate or they will die

advantages and disadvantages of replanting hedges

advantages

• greater biodiversity so increase in predators of pests

• increase in pollinators so more yield

disadvantages

• increase in pests which could damage crops

• reduced land area for crop growth

• more difficult to farm therefore less income

What impact does agriculture have on genetic diversity?

decreases

• farmers select certain characteristics, which reduces number of different alleles in the population

What are the 2 factors affecting genetic variation?

1. Genetic factors (genes and alleles present)

2. Environmental factors (food/climate/lifestyle)

How can biodiversity be increased in areas of agriculture?

1. Use hedgerows instead of fences.

2. Rotate crops every season

3. Limit use of pesticides and herbicides.

3 reasons why a population might show very low levels of genetic diversity

1. Genetic bottleneck: population might've been very small

2. Founder effect: population may have been started by a small number of organisms

3. Inbreeding