Biodiversity Flashcards
What is genetic diversity?
The number of different alleles of genes in a population
Can you list the principles of natural selection in the evolution of populations?
Natural selection: organisms are better adapted to their environment, survive and reproduce in greater numbers, resulting in an increase in allele frequency.
Principles: Better adapted means higher survival rate so they reproduce
Increases likelihood of passing on their characteristics
Less adapted means lower survival rate so die
Lower likelihood of passing on characteristics
Organisms therefore subject to selection pressures due to their environment.
Explain how genetic diversity is a factor in enabling natural selection to occur:
Alleles may be ad/disadvantageous providing adaptations that a re anatomical/physiological/behavioural.
Can you describe directional selection, exemplified by antibiotic resistance in bacteria?
Original population mean represented optimum characteristics for existing conditions.
Introduction of antibiotics as a selection pressure favours bacteria with the favourable allele for antibiotic resistance
Survival rate of Ab resistant bacteria increases and other die
Reproductive success will increase allele frequency of Ab resistance, over many generations.
Shift the mean to new optimum for existing conditions.
What factors influence genetic diversity?
Mutation
Gene flow (new alleles by migration)
Explain how reproductive success affects allele frequency within a gene pool:
Increased reproductivity means increasing allele frequency over many generations, increasing the spread of an allele within the gene pool.
Can you describe how adaptations may be anatomical, physiological or behavioural?
Anatomical: structural/physical eg colour fur for camouflage.
Physiological: biological processes eg chemicals produced in venom.
Behavioural: cold blooded reptiles bask in the sun to absorb heat.
Can you describe stabilising selection, exemplified by human birth weights?
Occurs in stable environment.
Selection pressures of unfavourable phenotypes, too light and too heavy at either end.
Babies too light tend to have a lower survival rate outside the womb.
Babies too heavy are difficult to remove so also have lower survival ayes.
Reduced variability and range of population
Reducing opportunity for evolutionary change.
Can you describe Disruptive selection?
Disruptive selection: 2 selection pressures at either end.
Favours 2 extreme characteristics
2 extremes dominate and mean shifts to both directions.
How are species named?
Binomial naming: generic name (genus) + specific name (species) underlined when written.
What is a species?
Group of similar organisms that reproduce to produce fertile offspring
What are the principles of classification? Artificial vs Phylogenetic classification:
Artificial: differences useful at the time such as number of legs (and other analogue features = same function but different origin)
Phylogenetic: evolutionary relationships between organisms and their ancestors.
Classifies species into groups using shared homologous features.
In a hierarchy: groups within groups with no overlap.
What is phylogeny?
Study patterns of evolutionary history: relatedness to a common ancestor.
Can you explain how we organise the groups of species? D K P C O F G S
Delicious King Prawn Curry Or Fat Greasy Sausages
Doman
Kingdom
Phylum
Class
Order
Family
Genus
Species
How does courtship help members of a species recognise each other?
Organisms which are more closely related display similar patterns of courtship behaviour,, genetically predetermined.
Species specific examples:
Fireflies give off light pulses
Birds have displays of feather colours
Male butterflies release distinct chemicals
What is the role of courtship in ensuring successful mating?
Attracts same species
Attracts Opposite sex
Indication of fertility
Stimulates gamete release
Form a pair bond
What are some difficulties of defining a species?
Cannot always observe reproductive behaviour of a species.
Cannot tell if their offspring are fertile.
Reasons:
Extinct
Produce asexually
Ethical/practical issues
What is meant by biodiversity?
Number of different species and the number of individual of each of thees epics within any one community.
Can you describe the impact of agriculture on species diversity?
Natural plants and animals are lost when land is cleared and ploughed.
Reduce variety in food sources and habitats.
Growth of crops and animals is controlled or stopped.
Pesticides may be used to kill unwanted species and fertilisers encourage growth of a dominant species.
What is meant by species diversity?
Measure of the number of different species in a community.
What is meant by genetic diversity?
Differences in DNA sequence.
What is meant by ecosystem diversity?
Differences / variety in ecosystems and habitats.
What is a diversity index and how is it used as a measure of species diversity?
Measure of biodiversity that takes into account species richness and evenness.
D= sum of every individual in all species x sum-1 / sum of each species x sum of each species -1
Greater diversity in X than Y
Can you explain the balance between conservation and farming?
Maintaining biodiversity prevents extinction
Some species may be important financially:
Medical uses
Commercial products
Tourism
Saving local forest communities
How can you identify genetic diversity within, or between species by using the frequency of measurable or observable characteristics?
Least reliable: legs, seeds, colour, fur wings etc.
How can you identify genetic diversity within, or between species by using the base sequence of DNA?
DNA hybridisation
Maternal mitochondrial DNA from zygote can be dates assuming constant mutation over time.
How can you identify genetic diversity within, or between species by using immunological comparison of proteins?
Inject a rabbit with a protein interested in from species x.
Extract antibodies.
Mix antibodies with proteins from different species.
Agglutination/precipitation produces comparable results, larger mass means more relatedness.
How is variation measured?
Range of phenotypic differences.
Differences in the base sequence of DNA/ Genetic code.
How can you identify genetic diversity within, or between species by using the base sequence of mRNA?
Retrieve mRNA from cytoplasm produce complementary DNA
Compare to other cDNA strand.
How can you identify genetic diversity within, or between species by using the amino acid sequence of the proteins encoded by DNA and mRNA?
Compare amino acids sequences for a specific protein eg cytochrome C
Shows genetic relatedness.
What is sampling and why is it used?
Used to investigate abundance and distribution of species in a population.
Taking a group out of a larger population to generalise characteristics/ features of a population.
How do we minimise the effect of chance when sampling?
Use random sampling and take many repeats of a sample.
What are the different types of variation and their causes?
Genetic, phenotypic, behavioural and physiological.
How do you calculate the mean, mode and median?
Mean- all values / number of values
Median- Middle value, order and n+1/2
Mode- Most common number(s).
What is the normal distribution curve?
Bell shaped curve symmetrical about the mean.
95 % of data within 2 SDs
100 within 3 SDs
What does SD show?
Measure of spread around the mean
