Doversity Flashcards
Genetic diversity scaffold
-random mutations -variation of alleles
-some alleles have a selective advantage
-those without adv die and can’t reproduce
-more with adv alleles in pop as allele freq increases
Agriculture
Natural ecosystem - from complex community
Agriculture - controlled + selected more productive crops - lower allele freq
Economy
Crop yield must be large- little room for anything else
Any one area can only support a certain amount of biomass
Chemicals
Pesticides and man made fertiliser further disadvantages and excludes unwanted species
Eutrophication
Destruction of hedgerows
Reduces diversity
A shape accommodates lots of species
Biodiversity
Number and variety of living organisms in the living world often measured in a particular area
Biodiversity importance
Boosts ecosystems productivity
Natural sustainability
Better withstands and recovers from disasters
How are organisms classified
Taxonomy
Classifying living organisms naming and group assigning based on similarities and differences
Phylogeny
- evolutionary history of relationships between groups of organisms
-more sophisticated than simple hierarchies - biochemical genetic evidence based
- shows ancestry and points of divergence from a common ancestor
Hierarchy
Groups are subdivided into smaller groups that don’t overlap
Groups go from big to small
Population
A group of organisms of the same species that occupy the same place at the same time
Genetic drift
The change in allele frequencies of a gene pool due to chance events (they happen randomly by mutations across generations)
Gene pool
The collection of genes within an interbreeding population at a particular time
Gene flow
Movement of genes from one population to another
The founder effect
2) The founder effect describes what happens when just a few organisms from a population start a new colony.
It can lead to an increased incidence of genetic disease because only a small number of organisms have contributed to the gene pool, so there are only a small number of alleles present in the population. There’s more inbreeding in the new population, which can lead to a higher incidence of genetic diseas
Non random mating - interbreeding
Non-random mating occurs when there is a bias for or against mating with related individuals.
Inbreeding is preferential mating with relatives.
Inbreeding is a common form of non-random mating.
Inbreeding increases the frequency of homozygosity relative to random mating, elevating the frequency of recessive genetic disorders.
Selectional pressure
an environmental force which can alter the frequency of alleles in a population
• Directional
• Stabilising
• Disruptive (less common, more complex)
Directional selection
• If e.g an environment changes.
• The ‘selection pressure’ will be exerted
on a particular portion of the population.
Stabilising selection
• When a both ends of the population are selected against
Disruptive selection
Selection pressure is on the MEAN of the population.
Causes of variation
• Mutations
• Meiosis
•
-Crossing over / recombination • -Independent assortment
• Random fertilisation of gametes
Continuous Variation
• No distinct catagones
• Tends to be quantitative
• Controlled by a lot of genes
•Strongly influenced by the environment
Discontinuous Variation
• Distinct catagories
• Tends to be qualitative
• Controlled by a few genes
• Unaffected by the environment
