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