Genetic Diversity And Biodiversity Flashcards
What is genetic diversity?
Number of different alleles of genes in a population
What are alleles and how do they arise?
● Variations of a particular gene (same locus)→ different DNA base sequence
● Arise by mutation
What is a population?
A group of interbreeding individuals of the same species.
Explain the importance of genetic diversity
● Enables natural selection to occur
● As in certain environments, a new allele of a gene might benefit its possessor
● By resulting in a change in the polypeptide (protein) coded for that positively changes its properties
● Giving possessor a selective advantage (increased chances of survival and reproductive success)
What is evolution?
● Change in allele frequency (how common an allele is) over many generations in a population
● Occurring through the process of natural selection
Explain the principles of natural selection in the evolution of populations
Mutation Random gene mutations can result in [named] new alleles of a gene
2. Advantage In certain [named] environments, the new allele might benefit its possessor
[explain why]→ organism has a selective advantage
3. Reproductive success Possessors are more likely to survive and have increased reproductive success
4. Inheritance Advantageous allele is inherited by members of the next generation (offspring)
5. Allele frequency Over many generations, [named] allele increases in frequency in the population
Describe 3 types of adaptations
● Anatomical- structural / physical features that increase chance of survival
● Physiological- processes / chemical reactions that increase chance of survival
● Behavioural- ways in which an organism acts that increase chance of survival
Example of directional selection
Directional selection
Antibiotic resistance in bacteria
Organisms with an extreme variation of a trait eg. bacteria with high level of resistance to a particular antibiotic
Yes, usually eg. antibiotic introduced
• Increased frequency of organisms with / alleles for extreme trait
• Normal distribution curve shifts
towards extreme trait
Example of stabilising selection
Stabilising selection
Human birth weight
Organisms with an average / moda variation of a trait eg. babies with ai average weight
No, usually stable
• Increased frequency of organism with / alleles for average trait
Normal distribution curve similar, less variation around the mean
What is a species?
A group of organisms that can (interbreed to) produce fertile offspring
Suggest why 2 different species are unable to produce fertile offspring
● Different species have different chromosome numbers → offspring may have odd chromosome number
● So homologous pairs cannot form → meiosis cannot occur to produce gametes
Explain why courtship behaviour is a necessary precursor to successful
mating
● Allows recognition of members of same species → so fertile offspring produced
● Allows recognition / attraction of opposite sex
● Stimulates / synchronises mating / production / release of gametes
● Indicates sexual maturity / fertility
● Establishes a pair bond to raise youn
Describe a phylogenetic classification system
● Species (attempted to be) arranged into groups, called taxa, based
on their evolutionary origins (common ancestors) and relationships
● Uses a hierarchy:
○ Smaller groups are placed within larger groups
○ No overlap between group
Name the taxa in the hierarchy of classification
Domain (largest / broadest)→ kingdom → phylum → class → order → family → genus → species (smallest)
How is each species universally identified?
A binomial consisting of the name of its genus and species, eg. Homo sapiens
Suggest an advantage of binomial naming
Universal so no confusion as many organisms have more than one common name.
How can phylogenetic trees be interpreted?
● Branch point = common ancestor
● Branch = evolutionary path
● If two species have a more recent common
ancestor, they are more closely related (eg. C & D)
Describe two advances that have helped to clarify evolutionary
relationships between organisms
- Advances in genome sequencing → allowing comparison of DNA base sequences
● More differences in DNA base sequences → more distantly related / earlier common ancestor
● As mutations (change in DNA base sequences) build up over time - Advances in immunology → allowing comparison of protein tertiary structure (eg. albumin)
● Higher amount of protein from one species binds to antibody against the same protein from
another species → more closely related / more recent common ancestor
● As indicates a similar amino acid sequence and tertiary structure
● So less time for mutations to build up
What is biodiversity?
● Variety of living organisms (species, genetic and ecosystem diversity)
● Can relate to a range of habitats, from a small local habitat to the Earth
What is a community?
All populations of different species that live in an area.
What is species richness?
A measure of the number of different species in a community
What does an index of diversity do?
Describes the relationship between:
1.The number of species in a community (species richness)
2. The number of individuals in each species (population size)
Suggest why index of diversity is more useful than species richness
● Also takes into account number of individuals in each species
● So takes into account that some species may be present in small or high numbers
What is the formula for index of diversity?
d= N(N-1)
————-
Σ n (n -1)
N = total number of organisms of all species
n = total number of organisms of each species, Σ = the sum of
Σ
List the steps involved in calculating an index of diversity
- Calculate the total number of organisms (N), if not given
- Multiply N by (N - 1)
- For each species, multiply the number of organisms (n) by (n - 1)
- Add up all the values of n(n - 1) to get Σn(n - 1)
- Divide N(N - 1) by Σn(n -
Describe how index of diversity values can be interpreted
● High → many species present (high species richness) and species evenly represented
● Low → habitat dominated by one / a few species
Explain how some farming techniques reduce biodiversity
Removal of woodland and hedgerows
Monoculture (growing one type of crop)
Use of herbicides to kill weeds
All leads to reduced variety of plants, less habitats, and less variety of food sources
Use of pesticides to kill pests - predator population of pests decreases
Explain the balance between conservation and farming
● Conservation required to increase biodiversity
● But when implemented on farms, yields can be reduced, reducing profit / income for farmers
○ Eg. by reducing land area for crop growth, increasing competition, increasing pest population
● To offset loss, financial incentives / grants are offered
●
Give examples of how biodiversity can be increased in areas of agriculture
● Reintroduction of field margins and hedgerows (where farmers only grow one type of crop)
● Reduce use of pesticides
● Growing different crops in the same area (intercropping)
● Using crop rotation of nitrogen fixing crops instead of fertilisers
● Reintroduction of field margins and hedgerows (where farmers only grow one type of crop)
● Reduce use of pesticides
● Growing different crops in the same area (intercropping)
● Using crop rotation of nitrogen fixing crops instead of fertilisers
● Comparing frequency of measurable or observable characteristics
● Comparing base sequence of DNA
● Comparing base sequence of mRNA
● Comparing amino acid sequence of a specific protein encoded by DNA and mRN
Explain how comparing DNA, mRNA and amino acid sequences can indicate
relationships between organisms within a species and between specie
● More differences in sequences → more distantly related / earlier common ancestor
● As mutations (change in DNA base sequences) build up over time
● More mutations cause more changes in amino acid sequences
Explain the change in methods of investigating genetic diversity over time
● Early estimates made by inferring DNA differences from measurable or observable characteristics
○ Many coded for by more than one gene → difficult to distinguish one from another
○ Many influenced by environment → differences due to environment not genes
● Gene technologies allowed this to be replaced by direct investigation of DNA sequences
Explain the key considerations in quantitative investigations of variation
within a species
● Collect data from random samples (use a random number generator)→ removes bias
● Use large sample size (or sample until stable running mean)→ representative of whole population
● Ethical sampling (where applicable)→ must not harm organism / allow release unchanged
● Calculate a mean value of collected data and standard deviation of that mean
● Interpret mean values and their standard deviations (S.D)
○ S.D shows spread of values about the mean → higher S.D = higher variation
○ If standard deviations overlap, causing values of two sets of data to be shared, any difference
between the two may be due to chance / not significant
● Use [named] statistical test → analyse whether there is a significant difference between populations
