11 Classification

Classification

Is the way in which living organisms are divided into groups

Taxonomy

The scientific practice of grouping organisms based on shared characteristics

Hierarchal

Consists of:

- smaller groups within larger groups

- no overlap between groups

Phylogenetic

• Based on the evolutionary history of organisms, i.e. their common ancestry.

• The closer the branches, the closer the evolutionary relationship, therefore the more recently they shared a common ancestor

8 main taxonomic ranks (hierarchical)

· Domain

· Kingdom

· Phylum

· Class

· Order

· Family

· Genus

· Species

Largest to smallest

What is the binomial name?

Genus species

Phylogenic tree

This reflects the evolutionary relationship between organisms. ,

Looks at similarities and differences in structure and function (represented by phylogenetic tree)

Each branch represents where divergence occurred (i.e. where a common ancestor evolves to become new species).

The closer the branches, the closer the evolutionary relationship, therefore the more recently they shared a common ancestor

Species

A group of organisms with similar characteristics that can interbreed to produce fertile offspring

Courtship behaviour

• Courtship behaviour is innate- genetically determined, allows for fertile mating

• All members of the same species are genetically programmed to show exactly the same courtship behaviour as they share the same genes.

Courtship behaviour allows...

• Species recognition - ensures fertile offspring produced

• Synchronising reproductive behaviour - max chance of fertilisation

• Identify a mate that is capable of breeding

• Formation of a pair bond - keeps male + female together - increases survival chances of offspring

• Stimulating production of gametes

Examples of courtship behaviour

• A display of breeding colours

• A dance

• A song - especially in nocturnal animals

4 different ways of investigating genetic diversity

1. The frequency of measurable or observable characteristics

2. The base sequence of DNA

3. The base sequence of mRNA

4. The amino acid sequence of the proteins encoded by DNA and mRNA.

What do the base / amino acid sequence coded for / of mRNA and DNA tell us about genetic diversity?

The more similar the base sequence of mRNA/DNA / amino acid sequence, the more closely related the organisms and they share a more recent common ancestor

Samples should be:

• Large: (20), more representative of the population and minimise the influence of chance on the results

• Random: this avoids bias and ensures that every member of the population has an equal chance of being included in the sample

Standard deviation

• Standard deviation is a measure of the spread of values about the mean and thus indicates the extent of variation a population shows

• The standard deviations overlap so no significant difference between the two means.

• No overlap so difference is likely to be significant, i.e. is not likely to be due to chance.

• If no overlap of the 2 x SD, you can be much more confident about concluding that there is a significant difference between the means

• If they ask for 2SD, multiply SD by 2

• Reduce the impact of extreme data points