Biological Change over Time
Ms. CowmanSBI3U
Mutations: The Source of Genetic Variation• All species exhibit genetic variation• Mutations create new genes that provide a continual
supply of new genetic information
• Mutations may be:NEUTRAL- provide no benefit or harm to the individualHARMFUL- reduce the reproductive success of an organism, do no accumulate over timeBENEFICIAL- produce a change in the individuals phenotype that gives the individual an advantage, accumulate over time
Mutations can have significant consequences
• Bacteria have developed resistance to antibiotics are becoming more widespread as less-resistant strains are killed off.
• Viruses can mutate to become more virulent (harmful), which can increase its ability to spread.
Selective Breeding: Artificial Selection of Traits
• Domestication of Animals and PlantsProvide humans with the majority of our food
supplyFormed the basis for the development of modern
civilization
• Domestication is the changing of members of a species to suit human needs through controlled captive breeding (Artificial Selection)
Examples of Artificial SelectionFirst species to be domesticated: Canis lupus, the wolf
Wild Sea Cabbage (1000’s of years) 7 vegetables
How does artificial selection work?
• The breeder picks seeds from the plants that have the best flavour or largest fruit and sows them
• The plants cross-pollinate each other producing more fruit with the desired trait
Genetic Engineering
• Transfer beneficial genes from an individual of one species to an individual of another species
• If successful, genetically modified individual is mass produced
Power of Artificial Selection• Production of individuals that exhibit traits that
are far beyond the natural variability present in the original population
• Can reduce genetic diversity within a population Breeder favours only certain traits in a
population, then many alleles linked to other versions of a particular characteristic are reduced or eliminated
Implications for Natural PopulationsWhat do we know about genetics? - All species exhibit genetic variation
- Mutations produce heritable changes in individuals, and these changes may be beneficial, harmful, or neutral
- Some species, such as bacteria and insects, can change over relatively short periods of time
- Some domesticated species have changed dramatically under the influence of artificial selection