Genetic diversity Flashcards
What is genetic diversity?
Number of different alleles of a gene in a population
What is evolution?
- Natural selection leads to evolution
- Change in allele frequency in a population over many generations
What is natural selection?
- Results in species becoming better adapted to their environments
- Adaptations can be anatomical, physiological, behavioural
Explain the process of natural selection
1) Random mutation = new alleles
2) If new alleles = increased chance of survival in that environment = individual likely to survive + reproduce
3) Reproduction = passing of advantageous alleles to next generation
4) Over many generations new allele increases in frequency
2 Types of selection
1) Directional
2) Stabilizing
Describe directional selection
- Occurs when there is change in the environment
- Adapted individuals will survive and pass on gene
- Over time mean of the population will shift to these characteristics
Example of directional selection
-Antibiotic resistance
- Bacteria with a mutation allowing them to survive in the presence of antibiotics will reproduce
- Therefore frequency of this allele will increase and the population will shift to have greater antibiotic resistance
Describe stabilizing selection
- Occurs when environmental conditions stay the same
- Individuals closest to the mean are favoured = selected against new characteristics
- Low diversity
Example of stabilizing selection
- Birth weight
- Babies that weigh around 3kg are more likely to survive than those at lower or higher weights
What is a species?
Group of organisms that can interbred = fertile offspring
Describe binomial system
- 1st name genus = capital
- 2nd name species = small case
- In italics
- The same genus = close relationship but cannot produce fertile offspring
What causes different species to look similar?
- Live in similar environments = similar selection pressures
- Similar alleles will be advantageous = produce similar proteins = similar characteristics
What is classification?
Process of arranging organisms into groups
What is a hierarchy?
- Smaller groups arranged within larger groups
- No overlap between groups
8 taxas of a hierarchy
1) Domain
2) Kingdom
3) Phylum
4) Class
5) Order
6) Family
7) Genus
8) Species
Why do we need a classification system?
- Understand relationships between organisms and keep track of the change
- Universal
Disadvantage of old classification techniques
- Originally based on physical differences in appearance, fossils, behaviour
- Disadvantage as sometimes same species look completely different/ different species look very similar
Modern classification methods
- DNA base sequence
- mRNA base sequence
- Amino acid base sequence
- Immunological comparison of self antibodies
Describe phylogenetic classification
Process of arranging organisms into groups according to evolutionary origins + relationships
Describe courtship ritual
- Sequence of actions that is unique to a species
- How animals identify members of their own species to mate with
- Attract a mate
- Mostly preformed by male
Examples of courtship rituals
- Dances
- Sound
- Release of pheromones
- Colorful feather/fur
- Fight with competitors
Importance of courtship
ENSURE SUCCESSFUL REPRODUCTION:
- Recognize own species/ opposite sex
- Synchronize mating behaviour displays sexually mature + in season
SURVIVAL OF OFFSPRING
- Form pair bond
- Choose strong + healthy mate
What does studying courtship rituals show us?
- How closely related species are
- More similar the courtship sequence = more closely related
What is biodiversity?
- Variety in living organisms measured in terms of:
- Species diversity: Number of species in a community
- Ecosystem diversity: Range of different habitats
- Genetic diversity: Variety of genes amongst the population of a species
What is species richness?
Number of different species in a particular area in a particular time
How does farming reduce biodiversity?
- Destruction of hedgerows
- Selective breeding
- Monocultures
- Over-grazing
- Filling in ponds + draining wetland
Compromise between conservation and farming
- Use hedgerows instead of fencing/ only remove a certain amount
- Crop rotation/ rows of different species
What is index of diversity?
Calculation to measure the relationship between the number of species in the community and the number of individuals in each species
How to calculate index of diversity?
- n = total no. of organisms for a single species in the community
- N = total no. of organisms in the community
- Σ = sum of
