Cell Diversity Within A Community Flashcards
What is biodiversity
The variety of all life on earth
What are the three levels of biodiversity
-Intraspecific/genetic diversity (variety of alleles within a species)
-Interspecific/species diversity (variety of species within a habitat)
-Ecosystem diversity (variety of habitats within an ecosystem)
What is intraspecific diversity due to
Variation in DNA (alleles) or variation in an environment
How is every individual in a species genetically unique
-mutations
-crossing over
-random fertilisation
What are the two types of variation within a species
Continuous variation
Discontinuous variation
Continuous variation
-The frequency histogram is a smooth curve
-some times there is a continuous range of values
Continuous variation characteristics
-no distinct categories in which to place individuals
-quantitative
-controlled by numerous genes (polygenic characteristics)
-significantly affected by environment
Examples of continuous characteristics
Height
Hair colour
BMI
Growth
Rate of photosynthesis
What is discontinuous variation
The characteristics have a few discrete categories (blood group)
The frequency histogram has separate bars
Discontinuous variation characteristics
- Have a few distinct categories which individuals can be placed into
-Tends to be qualitative with no overlap between categories
-Are controlled by one or a small no. of genes
-Are unaffected by the environment
Examples of discontinuous characteristics
Rare in animals but common in plants
Blood group, detached earlobe, flower colour
What is the majority of intraspecific variation caused by/examples
A combination of genes and environment
Eg. Height is a combination of genes and nutrition
How / Why do we use twin studies
To compare the variation in characteristics between identical and non identical twins and determine the extent to which the differences are caused by the environment
Why is high intraspecific/genetic diversity good for a species
Species with high genetic diversity = more individuals with the characteristics needed to survive in a changing environment
Why do some populations have low genetic diversity
-Genetic bottlenecks
-Founder effect
-Selective breeding
What is interspecific/species diversity
The variety of a species in a community
What is a community
All the organisms living in a habitat
Why is species diversity important
Because it tells us about the complexity, quality and stability of that ecosystem
How do we measure a species diversity
Random quadrats in a specific area / along a transect helps you equate the species richness
Issues with measuring the number of species
It doesn’t inform you of the abundance of the species
There can be 25 species in a field but 95% of that field
Why are we having an increase of extinction leading to another mass extinction
Human activities eg.
Deforestation, agriculture, habitat reduction, hunting, pollution
What are the main threats that agriculture has on species diversity
Intensive farming
Selective breeding
Large farms
Monoculture
Fertilisers/pesticides
Why is selective breeding an issue
It reduces the genetic diversity within a species
Why are large farms such an issue
They result in the destruction of hedgerows which provide habitats for hundreds of different species
Act as wildlife corridors allowing wildlife to move safely
Why is monoculture such an issue
It reduces the species and genetic variety in favour of fast growing good quality crop
It renders all crops to be susceptible to disease and reduces animal species diversity because there are fewer ninches
Why is fertiliser such a bad thing
Because they pollute the surrounding ground water causing eutrophication and killing aquatic animals
