3.1.11 Biodiversity within a Community Flashcards
What is genetic diversity?
Differences in the DNA of organisms
Name and explain 2 ways in which genetic diversity can be increased within a population
- Mutations in DNA
- Creates new alleles
- Gene flow
- Different alleles being introduced to populations when individuals from another population migrate into them and reproduce
What does genetic diversity allow to occur?
Natural selection
Why is it that a species with a greater genetic diversity is more likely to adapt to an environmental change?
∵ have wider range of alleles = wider range of characteristics
∴ greater probability that some individual will possess a characteristic that’s suits the new environmental condition
Genetic diversity can be measured by comparing… (name 3 things)
- Base sequence of DNA or of mRNA
- Frequency of specific base sequences or alleles in population
- Amino acid sequence of encoded proteins
What is a genetic bottleneck?
Event that causes big reduction in population
Describe how genetic bottlenecks reduce genetic diversity
Reduces number of different alleles in gene pool = reduces genetic diversity
(Survivors reproduce and larger population is created from few individuals)
Describe the founder effect
- Small group of organisms become separated from main population & found a new colony
- Small group = small no. of different alleles in initial gene pool and have no choice but to breed with each other
- Decreases the genetic diversity in population
What does the founder effect occur due to?
Migration (separation of a specie)
Describe how the founder effect may lead to higher incidence of genetic disease (3)
Small colony and one person may carry faulty allele for a genetic disease
- Less genetic diversity / smaller gene pool
- Individuals breed within group / do not breed with outsiders
- Higher chance of inheriting allele
Describe how selective breeding reduces genetic diversity
- Individuals with desired characteristics are breed together to pass on the desired alleles
- Variety of alleles within population is deliberately restricted to small no. of desired alleles
- Leads to population that possess only desired alleles
What is biodiversity?
Variety of living organisms in an area
Define species richness
No. of different species in a community
Define species evenness
Abundance of each species
State the formula for the index of diversity & state what each symbol/letter represents
The higher the index of diversity, the more…
diverse the area is = habitat is more likely to withstand any change
If all individuals are of same species, the index is ___
1
Name 5 agricultural practices that can reduce biodiversity
- Woodland clearance - to increase area of farmland
- Hedgerow removal - increase area of farmland turning lots of small fields into fewer large fields
- Pesticides - chemicals that kill organisms (pests) that feed on crops
- Herbicides - chemicals that kill unwanted plants (weeds)
- Monoculture - fields containing only one type of plant
Describe how woodland clearance reduces biodiversity
- Fewer plant species
- Less habitats and less food sources
- Species will die or migrate = reducing biodiversity
Describe how pesticides reduce biodiversity
- Reduces diversity = directly killing pests
- Species that feed on pests = lose food source ∴ their numbers decrease
Describe how monoculture reduces biodiversity
Single type of plant - reduces biodiversity directly & supports fewer organisms (e.g. as habitat/food source) reduces further biodiversity
Name 4 examples of incentives/restrictions to encourage sustainable agriculture
- Financial incentives from governments to introduce features e.g. buffer strips
- Financial incentives (tax relief) for restoring/managing areas of woodland that been deforested for farming
- Restricting expansion of agricultural land in favour of improving productivity in current areas
- Removing subsides for production
Give 2 conservation schemes examples
- Giving legal protection to endangered species
- Creating protected area = restrict further development
2.68(6)
Explain why it may be more useful to calculate the index of diversity than to record only the number of species present (2)
- Measures number of individuals of each species & number of species
- Some species may be present in low/high numbers
The points on the graph have been joined with straight lines rather than with a smooth curve. Explain why.
Cannot predict/don’t know the intermediate values
