bio test genetic diversity Flashcards
What is genetic diversity?
The number of different alleles within a population.
What is a population?
A population is a group of the same species in the same place that can interbreed.
What is the advantage of more genetic diversity?
More genetic diversity + more alleles means a wider range of characteristics/variation (bigger gene pool), which leads to a greater chance of individuals surviving environmental change.
What is the model paragraph for mutations and selection pressures?
- A change in environment causes a selection pressure.
- Random mutations produce genetic diversity.
- Some alleles provide an advantage to gaining resources.
- Those individuals with the alleles survive and reproduce.
- Advantageous alleles are passed on.
- The frequency of advantageous alleles in the population increases.
- The frequency of mutation increases.
What decides if a mutation is advantageous?
Nature and natural selection.
What are the features of variation between species?
Different species have different genes, they may also have a different number of chromosomes, they cannot breed to produce fertile offspring and have different features.
What is selection?
The process by which organisms that are better adapted to their environment survive and reproduce, while those who are less well adapted do not.
What is selection pressure?
An environmental change that leads to selection.
What is continuous variation?
A characteristic that can have a wide range of values. Producing a histogram shows a ‘bell shaped’ normal distribution curve.
What is discontinuous variation?
A characteristic with few possible values shows discontinuous variation. The graph does not show a bell curve.
What are polygenic traits?
characteristics that are controlled by mutiple genes/alleles
What is direction selection?
Favouring individuals whose characteristics vary from the mean; phenotypes are selected for genotypes are indirectly selected. Changes characteristics.
What is stabilising selection?
If conditions remain stable, individuals with average characteristics are favoured; phenotypes at the extremes are selected against. Preserves characteristics.
Why do organisms reproduce?
Organisms reproduce to ensure they survive over time; the females of most species produce eggs at specific times. This places a selection pressure on courtship behaviours.
What are the features of courtship behaviour?
Allows individuals to:
1. Recognise members of the same species.
2. Identify a sexually mature mate.
3. Form a pair bond that will lead to successful mating and raising of offspring.
4. Synchronise mating so that it takes place at a time where egg and sperm are most likely to meet.
5. Become able to breed by bringing a member of the opposite sex into a state that allows breeding to occur.
What is artificial classification?
Grouping organisms based on features that are useful at the time, e.g. colour wings. The evolutionary origin of these features may not be taken into account.
What is phylogenetic classification?
Based on evolutionary relationships determined from fossils, DNA analysis; based on shared homologous features.
What are hierarchies?
Groups within groups that do not overlap.
What are the different taxonomic ranks?
Domains (divine), kingdom (kings), phylum (play), class (chess), order (on), family (fat), genus (green), species (stools).
What are the benefits of classification?
Universal.
What is species diversity?
The number of different species in a community and their proportions.
What is genetic diversity?
The frequency of different alleles within a population.
What is ecosystem diversity?
The number of different habitats that make up an ecosystem.
What is species richness?
The number of different species in a community. It only tells you the number of species in an area and not the proportions of individuals.
What is the index of diversity?
A quantitative measure of biodiversity.
How do you calculate the index of diversity?
d = N(N-1)/En(n-1), where d = species diversity index, N total is the number of individuals of all species, n = no. of individuals of each species.
What is a natural ecosystem?
An ecosystem consists of a community of organisms and the habitats in which they live.
What is an artificial ecosystem?
An ecosystem that is controlled by humans; farmers select which species are allowed to grow there. They have a low genetic diversity, species richness and index of diversity.
What impact do artificial ecosystems have on biodiversity?
By reducing competition, few species dominate; genetic diversity decreases; species richness decreases; index of diversity decreases; fewer habitats; variety of plants/insects/animals decrease; variety of food decreases.
How can we determine evolutionary relationships?
Comparing physical characteristics, comparing proteins/enzymes, compare amino acids, compare mRNA sequences, compare DNA sequences.
How are mutations linked to DNA sequencing?
Organisms accumulate random mutations over time; more closely related species show more DNA similarities. This allows for phylogenetic classification.
How do you compare mRNA sequences?
mRNA is complimentary to DNA from which it is transcribed. Therefore, species that share similar mRNA sequences are more closely related.
How do you compare amino acid sequences?
Amino acid sequences are determined by mRNA sequences, which are determined by DNA sequence. More closely related species will have more similarities in amino acid sequences.
How can you compare species using immunological comparisons?
Antibodies of one species will respond to specific antigens on proteins in the blood serum of another. Serum containing the antigen from species A is injected into species B. Species B produces antibodies specific to all the antigen sites on the antigen from species A. The serum is extracted from species B. This serum contains antibodies specific to the antigens in serum A. Serum from species B is mixed with serum from the blood of a third species C. The antibodies respond to their corresponding antigens in the serum of species C. The response is a formation of a precipitate. The greater the number of similar antigens, the more precipitate and vice versa. Higher precipitate = a more closely related species.
How do you measure variation?
Most characteristics show continuous variation; this makes it impossible to give them a definitive measurement value. You can get around this by sampling.
What is sampling?
Looking at smaller groups of organisms and using them to represent the whole population.
What are the errors that can be made when sampling?
May show bias like choosing where to collect samples.
What is random sampling?
Draw a grid over a map of the land; use a random number generator to generate coordinates; place the quadrant at coordinates. This eliminates sampling bias.
How can you do random sampling with leaves?
Number the leaves; place numbered balls in a bag; select balls at random.
What are the downsides of sampling?
Chance. Even without bias, the measured value may be down to chance, e.g. 50 chosen buttercups may all happen to be tall ones.
How can you reduce the impact of chance?
Increase sample size or more/bigger quadrats.
How do you display variation?
If you measured a characteristic of a population that showed continuous variation under stable conditions, it would present a normal distribution: symmetrical, mean, median and mode values are the same.
Why may a distribution curve be skewed?
This may be because of insufficient sampling or an external factor/selection pressure favouring a characteristic.
What is the standard deviation?
The spread of data about the mean. The bigger the standard deviation, the greater the variation.
How do you calculate the standard deviation on a calculator?
- Press mode.
- Select STAT.
- Select 1–VAR.
- Enter the first measurement and press = to enter it.
- Continue to enter other measurements, pressing enter each time.
- When done, press M+ to add values to memory.
- Clear screen and press shift.
- Press STAT button.
- Select ‘sx’ if calculating s.d for a sample or press ‘OX’ if calculating s.d for a whole population.
- Press M+.
- The number given is the standard deviation.
What does it mean if the standard deviation in two sets of data overlaps?
The results are not significant
What is interspecific variation?
Variation in characteristics between species.
What is intraspecific variation?
Variation in characteristics between members of the same species.
How can you reduce the impact of chance in sampling?
Carry out a statistical test - this tells you exactly how confidently you can be that the result is not due to chance. We usually aim to be 95% confident.
What are the 5 kingdoms?
- animalia, plantae ,fungi protocista, prokaryotae..
- all eukaryotic domains have dna in a membrane bound nucleus.
what are the three domains?
- eukarya
- archaea
- bacteria
