Genetic diversity Flashcards
(29 cards)
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
