Diversity and Classification Flashcards
1
Q
Artificial Classification
A
Divide organisms based on features like colours, size, number etc.
2
Q
Phylogeny
A
- Study of the evolutionary history of groups of organisms
- Tell’s us who’s related to whom and how closely related they are
- All organisms have evolved from shared common ancestors (relatives)- this can be shown on a phylogenetic tree
- Tree shows relationship between members of the Hominidae family (great apes and humans)
- First branch point represents a common ancestor of all the family members (this ancestor is now extinct)
- Orangutans were the first group to diverge (evolve to become a different species) from this common ancestor
- Each of the following branch points represents another common ancestor from which a different group diverged (Gorillas divereged, then humans etc…)
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Closely related species diverged away from each other most recently e.g. humans and chimpanzees are closely related, as they divereged very recently (branches are close together)
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3
Q
Taxonomy
A
- Science of classification
- Involves naming organisms and organising them into groups (makes it easier to identify and study them)
- Scientists now take into account phlogeny when classifying organisms, and group organisms according to their evolutionary relationships
- There are 8 levels of groups used to classify organisms (groups are called taxa and each group is called a taxon)
- Groups are arranged in a hierarchy, with largest groups at top and smallest groups at bottom
- Organisms can only belong to one group at each level in the hierarchy- there’s no overlap
4
Q
How are organisms sorted in taxonomy?
A
- First sorted into 3 large groups (or taxa) called domains- the Eukarya, Bacteria and Archaea
- Related organisms in a domain are then sorted into slightly smaller groups called kingdoms e.g. all animals in animal kingdom
- More closely related organisms from that kingdom are then grouped into a phylum, then grouped into a class, and so on down the 8 levels of the hierarchy
- As you move down the hierarchy, there are more groups at each level but fewer organisms in each group
- Organisms in each group also become more closely related
- Hierarchy ends with species- groups that contain only one type of organisms
- Scientists constantly update classification systems because of discoveries about new species and new evidence about known organisms e.g. DNA sequence data
- (demanding kids prefer chips over floppy green spinach)
5
Q
Species
A
Group of similar organisms able to reproduce to give fertile offspring
6
Q
The Binomial System
A
- Nomenclature used for classification- all organisms are given one internationally accepted scientific name in Latin that has 2 parts
- First part of the name is the genus name and has a capital letter
- The second part is the species name and begins with a lower case letter
- Names are always written in italics (or underlined)
- Humans are Homo Sapiens- Genus is Homo and species is sapiens
- Giving organisms a scientific name enables scientists to communicate about organisms properly to avoid confusion
- First name denotes the genus to which the organism belongs
- Second name denotes species to which organism belongs
- Some species have the same genus and species name
7
Q
What is courtship behaviour?
A
- Carried out by organisms to attract a mate of the right species
- Simple courtship behaviours- Releasing a chemical, using sound, visual displays
- Complex courtship behaviours- Dancing, building
- Can be performed by either the male or female, may sometimes involve both sexes
8
Q
Using courtship behaviour to classify species
A
- Courtship behaviour is species specific- only member of the same species will do and respond to that courtship behaviour
- Allows members of the same species to recognise each other, preventing interbreeding and making reproduction more successful (as mating with the wrong species won’t produce fertile offspring)
- Because of this specificity, courtship behaviour can be used to classify organisms
- The more closely related species are, the more similar thier courtship behaviour
- (Fireflies give off pulses of light, crickets make sounds, male peacocks show off colourful tails)
9
Q
Why courtship behaviour exists?
A
- Recognise members of own species to ensure mating occurs between members of same species- fertile offspring
- Identify a mate that is capable of breeding- sexually mature, fertile and receptive to mating
- Form a pair bond- lead to successful mating and raising offspring
- Synchronise mating so it takes place when maximum probability of sperm meeting egg
- Being able to breed by bringing opposite sex in physiological state for breeding to occur
10
Q
How do we clarify evolutionary relationships?
A
- New and improved technologies can result in new discoveries being made and the relationships between organisms being clarified
- This can lead to classification systems being updated
- Frequency of measurable or observable characteristics
- Amino acid sequence of the proteins encoded by DNA and mRNA
- Base sequence of mRNA
- Base sequence of DNA
11
Q
Genome Sequencing
A
- Advances in genome sequencing have meant that the entire base sequence of an organism’s DNA can be determined
- The DNA base sequence of one organism can then be compared to the DNA base sequence of another organism, to see how closely related they are
- Closely similar related species will have a higher percentage of similarity in their DNA base sequence
12
Q
Comparing amino acid sequence
A
- Proteins are made of amino acids- sequence of amino acids in a protein is coded for by the base sequence in DNA
- Related organisms have similar DNA sequences and so similar amino acid sequences in their proteins
13
Q
Immunological comparisons
A
- Similar proteins will also bind the same antibodies
- Proteins that bind antibodies will often form a precipitate in solution
- The more antibodies the protein binds, the more precipitate will form- so the amount of precipitate can be used to determine how similar 2 proteins are
14
Q
Comparing classifications
A
15
Q
How are gene technologies used to assess genetic diversity?
A
- Early estimates of genetic diversity were made by looking at the frequency of measurable or observable characteristics in a population e.g. people with particular eye colour
- Since different alleles determine different characteristics, a wide variety of each characteristic in a population indicates a high number of different alleles- and so a high genetic diversity
- However, gene technologies have now been developed that allow us to measure genetic diversity directly
- Example= Different alleles of the same gene will have slightly different DNA base sequences
- Comparing the DNA base sequences of the same gene in different organisms in a population allows scientists to find out how many alleles of that gene there are in that population
- Different alleles will also produce slightly different mRNA base sequences, and may produce proteins with slightly different amino acid sequences, so these can also be compared
- These new technologies can be used to give more accurate estimates of genetic diversity than can be made just by looking at the frequency of observable characteristics
- Also allow genetic diversity of different species to be compared more easily
16
Q
Variation
A
- Differences that exists between individuals
- There’s variation between species and within species
- Interspecific- variation between species
- Intraspecific- variation within species
17
Q
Causes of variation
A
- Can be caused by genetic factors
- Different species have different genes, which causes variation between species
- Individuals of the same species have the same genes, but different alleles which causes variation
- Can be caused by differences in the environment e.g. climate, food, lifestyle
- Combination of genetic and environmental factors e.g. genes determine how tall we are but nutrients affect growth too
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18
Q
Population Samples
A
- Only look at sample of population, not whole thing
- For most species it would be too ti e-consuming or impossible to catch all the individuals in the group
- So samples are used as models for the whole population
19
Q
Random Sampling
A
- Important that sample data accurately represents the whole population and that any patterns observed are tested to make sure they’re not due to chance
- To make sure sample isn’t biased, it should be random
- A sample is biased if it doesn’t represent the population as a whole
- Could be done by dividing grid using a random number generator to select coordinates
- To ensure variation observed isn’t due to chance, should analyse results statistically (can use mean and S.D to measure variation in a sample)
20
Q
Mean
A
- Average of the values collected in a sample
- Can be used to tell if their is variation between samples
- Most samples will include values either side of the mean, so you end up with a bell-shaped graph- called normal distribution
- A normal distribution is symmetrical about the mean
21
Q
Standard Deviation
A
- Tells you how much the values in a single sample vary
- Measure of spread of values about the mean ( 9 +- 3 means 9 is mean and the 3 is S.D, so most of the values are spread between 6 and 12
- Values with a larger standard deviation show greater variation
- S.D is one way of calculating the dispersion of data
22
Q
Another method of calculating dispersion?
A
- Looking at range- difference between highest and lowest figures
- S.D is more useful than range because it takes into account all values in the data set, whereas the range only use 2
- Makes range more likely to be affected by an anomalous result
23
Q
Using standard deviation to draw error bars
A
- Error bars extend one S.D above and one S.D below the mean (total length of an error bar is twice the S.D)
- The longer the bar, the larger the standard deviation and the more spread out the sample data is from the mean
- The smaller the error bars, the smaller the standard deviation and the less the data in the sample varies
24
Q
Ecosystem diversity
A
Range of different habitats
25
Q
Biodiversity
A
Variety of living organisms in an area
26
Q
Habitat
A
Place where an organism lives
27
Q
Community
A
All populations of different species in a habitat
28
Q
Local biodiversity
A
Variety of different species living in a small habitat that’s local to you (some habitats will be more diverse than others)
29
Q
Global biodiversity
A
Consider variety of species on earth (biodiversity varies in different parts of the world- greatest at equator)
30
Q
How can you measure biodiversity?
A
Species richness or an index of diversity
31
Q
Species diversity
A
Number of species in a community and the abundance of each species
32
Q
Species Richness
A
- Measure of number of different species in a community (simple measure for biodiversity)
- Can be worked out by taking random samples of a community and counting the number of different species
- Population sizes of species affects biodiversity
- Species that are in a community in very small numbers shouldn’t be treated the same as those with bigger populations
33
Q
Index of Diversity
A
The higher the number, the more diverse the area is (if all individuals are of the same species, the index is 1 beacuse no biodiversity)
34
Q
Index of Diversity table
A
35
Q
Conservation Techniques
A
- Maintain hedgerows at beneficial height
- Plant hedges rather than fences as boundaries
- Maintain existing ponds, if possible create new ones
- Leave wet corners of fields rather than draining them
- Reduce use of pesticides (organic fertilisers)(use biological control)
- Use intercropping rather than herbicides to control weeds and other pests
- Leave cutting of verges and field edges until after flowering and when seeds have dispersed
- Use crop rotation (nitrogen-fixing crop) rather than fertilisers to improve soil fertility
36
Q
The impact of agriculture on biodiversity
A
- Farmers try to maximise the amount of food they can produce from a given area of land (but many of the methods they use reduce biodiversity)
- Woodland clearance is done to increase the area of farmland
- It reduces the number of trees and sometimes the number of different tree species
- It also destroys habitats, so some species could lose their shelter and food source
- Means that species will die or be forced to migrate to another suitable area, further reducing biodiversity
- Hedgerow removal is also done to increase the area of farmland by turning lots of small fields into fewer large fields (reduces biodiversity for same reasons as woodland clearance)
- Pesticides are chemicals that kill organisms (pests) that feed on crops (reduces diversity by directly killing pests)
- Any species that feed on the pests will lose a food source, so their numbers could decrease too
- Herbicides are chemicals that kill unwanted plants (reduces plant diversity and could reduce the number of organisms that feed on the weeds)
- Monoculture is when farmers have fields containing only one type of plant
- A single type of plant reduces biodiversity and will support fewer organisms (reducing biodiversity further)
37
Q
Consevation Schemes
A
- Agriculture is one way of producing the resources we need from the environment- we need it to produce food and fibres for clothing, as well as some medicines and fuels
- Biodiversity helps maintain environment
- Provides us with new sources of food and medicines, and it benefits agriculture
- Needs to be a balance between agriculture and biodiversity
- Conservationists try to achieve this through conservation schemes
38
Q
Analysing effect of agriculture on biodiversity
A
- If you need to work out whether there’s a correlation between 2 variables or not, you can calculate the spearman’s rank correlation coefficient (r>s)
- This is a type of correlation coefficient and an example of a statistical test
- Rexult of the test is a muber between -1 and +1
- If -1, then there is a perfect negative correlation between 2 variables
- If +1, then there’s a perfect positive correlation
- Closer to 0, weaker the correlation
39
Q
What to do to find out if a result is statistically significant or not?
A
- First come up with null hypothesis
- Result of spearman’s rank test allows you to decide whether the null hypothesis can be rejected (to find out, consult a table of critical values)
- Result is compared to the critical value 0.05, which corresponds to data your looking at
- Value represents point at which the correlation your investigating would occur (5% chance correlation is down to chance)
- Can reject null hypothesis if the result of your test is higher than the value
- If result is negative, ignore minus
- If result is not statistically significant, it could be down to chance
40
Q
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