Topic 4: Species and Taxonomy Flashcards
What is classification?
The organisation of living organisms into groups based on shared features
What is a species?
A group of similar (physically, biochemically, developmentally + immunologically) organisms that can interbreed to produce fertile offspring.
They occupy the same ecological niche (role within an ecosystem). The basic unit of classification
Describe how species are named
The binomial system:
genus + species
(generic name + specific name)
What are the conventions of the binomial system of naming species?
- Written in italics / underlined if handwritten
- First letter of the generic name is in uppercase, the specific name is lowercase
- If the specific name is unknown, it can be written as ‘sp.’
What are the purposes of courtship behaviour?
- Species recognition + identification - allows organisms to recognise members of their own species (behaviour is genetically determined to different species have different behaviours) - ensures mating will produce fertile offspring
- Identifies a mate capable of breeding - both parents must be sexually mature + receptive
- Indicates fittest / healthiest male
- Forms a pair bond - leads to successful mating + raising offspring
- Synchronise mating - takes place with the maximum probability of sperm meeting an egg
What is taxonomy?
The theory and practice of biological classification
What are the principles of phylogenetic classification?
- Hierarchy - smaller groups placed within larger groups with no overlap between them
- Grouping based on common structures based on evidence
- Grouping reflects evolutionary history
Describe the two different types of classification
- Artificial - based on analogous characteristics (similar features but different evolutionary origins)
- Phylogenetic - based on evolutionary relationships - homologous characteristics (similar evolutionary origins regardless of functions)
What are taxons?
Each group within a phylogenetic biological classification
What is a taxonomic rank
The positions of each group in their hierarchical order
State the order of taxonomic ranks
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Name the three types of domain
Bacteria
Archaea
Eukarya
Describe the bacteria domain
Single-celled prokaryotes with:
- no membrane-bound organelles
- cell walls of murein
- 70S ribosomes smaller than eukaryotic cells
- A single loop of naked DNA with no histones
Describe the archaea domain
Single-celled prokaryotes, differ from bacteria with:
- Genes + protein synthesis more similar to eukaryotes
- Membranes contain fatty acid chains attached to glycerol by ether linkages
- No murein in cell walls
- Have a more complex form of RNA polymerase
Describe the eukarya domain
Organisms made from at least one eukaryotic cell. They have:
- Membrane-bound organelles
- Membranes with fatty acid chains attached to glycerol by ether linkages
- No murein in cell walls if present
- 80S ribosomes larger than bacteria/archaea
What are phylogenetic trees?
Diagrams showing evolutionary relationships. Oldest species are at the base with the most recent ones at the end
What is diversity and what is its three components?
The number and variety of different organisms in a particular area
- Species diversity
- Genetic diversity
- Ecosystem diversity
What is species diversity?
The number of different species and the number of individuals of those species in a community
What is genetic diversity?
The differences in DNA / genes possessed by individuals in one species
What is ecosystem diversity?
The range of habitats within a specified area
What is a habitat?
A place where a community of organisms normally lives
What is a community?
All the populations of different organisms interacting in a particular place at one time
What is an ecosystem?
All the living and non-living components of a specified area
What is species richness?
Why is it not often used?
The number of species in a particular area at a given time.
Doesn’t take into account the proportions each species takes up of the community - one species could dominate the area = not very diverse
What does Simpson’s diversity index show?
Includes the number of species and number of individuals of each species. Provides a quantitative measure of species diversity.
Give the Simpson’s diversity index equation
d = (N(N-1)) / (Σn(n-1))
d = diversity
N = total number of organisms of all species
n = total number of organisms of each species
Σ = sum of
Higher number for d = greater diversity. If all individuals are of the same species, d = 1
What causes deforestation?
Natural fires or deliberate human activity, e.g:
- Agriculture
- Grazing (cattle)
- Fuel (firewood / charcoal)
- Oil mining
- Roads / highways
- Housing
What are the consequences of deforestation?
- Soil erosion - leaching of ions, flooding and desertification
- Decrease in biodiversity
- Loss of potential medicines
- Atmospheric circulation - trees sequester carbon dioxide, preventing the build-up in the atmosphere, preventing global warming
Give some reasons why the rainforests should be conserved
- They maintain the food chain
- Ecological services (e.g water + soil regulation, climate etc)
- Resources (e.g medicine, timber etc)
What is conservation?
The concept of preservation / maintenance. Aims to maintain diversity and habitats/ecosystems
What is a monoculture?
The cultivation of a single species over a large area. Aims to increase the productivity of farmland (cultivates the best variety of a crop).
Allows multiple harvests per year, reduces labour costs and simplifies management
Describe the differences between natural and artificial ecosystems
Natural ecosystems - complex communities with a high species diversity index
Artificial ecosystems - species selected that contain the alleles exhibiting desired characteristics
Describe the impact of monocultures in large quantities on farmland
Creates profit. But:
Area is limited to the biomass it can support, so less land for other species = competition for space + resources
Pesticides exclude other species because they compete with the crop = overall reduction in species diversity + less stability (affected by climatic factors)
Give some examples of agricultural practices reducing diversity
- Removal of hedgerows + grubbing out woodland
- Creating monocultures
- Filling in ponds + draining marsh / wetland
- Overgrazing of land prevents woodland regeneration
- Pesticides / inorganic fertilisers
- Escape of effluent from silage stores + slurry leaks into water
- No crop rotation, intercropping or undersowing
Give some conservation techniques that can be used in agriculture
- Maintain hedgerows
- Plant hedges not fences
- Maintain ponds + wet field corners
- Plant native trees on undiverse land
- Reduce pesticide use
- Use organic fertiliser
- Use crop rotation with a nitrogen-fixing crop
- Use intercropping not herbicides
- Create natural meadows
- Leave cutting of field edges until after flowering
- Introduce conservation headlands - areas for wild flowers + insects at field edges
What are the 5 ways to investigate diversity?
- Comparing observable characteristics
- Comparing DNA base sequences
- Comparing mRNA base sequences
- Comparing protein amino acid sequences
- Immunological comparisons of proteins
Describe how you can investigate diversity by comparing observable characteristics
Characteristics are determined by genes - variety depends on the number and variety of alleles of that gene .
Limitations - many characteristics are polygenic - determined by many genes - so are often difficult to distinguish one from another. Can be modified by the environment
Describe how you can investigate diversity by comparing DNA base sequences
Done by machines + analysed by computers. Each nucleotide base is tagged with a different colour fluorescent dye. Patterns scanned by lasers + interpreted by software (human eye too slow).
When 1 species gives rise to another by evolution, DNA is initially very similar. Over time, new species accumulates more mutations so becomes more different = determines evolutionary history
Describe how you can investigate diversity by comparing mRNA base sequences
mRNA is complementary to DNA, so can also measure genetic diversity + evolutionary relationships
Describe how you can investigate diversity by comparing protein amino acid sequences
Determined by mRNA, and so DNA too. Similar sequences mean the species are more closely related. Must compare the same section of the same protein
Describe how you can investigate diversity by immunological comparisons of proteins
Antibodies of 1 species will respond to antigens in the blood serum of another. To compare species A and C:
- Blood serum albumin (antigens) removed from species A + injected into species B (known not closely related)
- B produces antibodies in response to non-self A antigens
- Antibodies from B are injected into C
- If C is similar to A, will have similar shaped antigens, so they will bind to the antibodies (agglutination), forming a precipitate.
- Higher volume of precipitate - more closely related
What is interspecific variation?
What is intraspecific variation?
- Variation between different species
- Variation between one species
How do biologists take measurements of populations?
Use samples of the population (can’t investigate every individual but results from just one are unreliable)
What is a sample?
A part of the population used to describe the characteristics of the whole population
What are the reasons why a sample may not be representative?
- Sampling bias - investigators make unrepresentative choices
- Chance
How would you ensure a sample is representative?
- Random sampling - removes human decisions (bias) e.g divide an area into a grid, assign coordinates, use a random number generator
- Large sample size - more individuals = smaller probability chance will affect result + less influence of anomalies = more reliable data
- Statistical analysis of data - determines the extent to which chance may have influenced the data
Generally describe the normal distribution curve
Bell-shaped, often used for features with continuous variation.
Symmetrical around the mean (max. height of the curve).
Mean, mode + often median have the same value
Curves always have the same basic shape but differ in max. height + width
What does skewed distribution mean on a normal distribution curve?
The curve is shifted to one side
Give the equation for standard deviation
s = √((Σ(x - mean x)^2) / (n-1))
What does standard deviation show?
Gives an indication of the range of values either side of the mean. Shows the distance from the mean to the point of inflection of the normal distribution curve
Why is standard deviation used?
The mean doesn’t provide information about the range of values in the sample.
It gives an idea of reliability and reduces influence of extreme ranges, allows statistical analysis
