Biological Change over Time

Ms. Cowman SBI3U

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 individual HARMFUL- reduce the reproductive success of an organism, do no accumulate over time BENEFICIAL- 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 Plants  Provide humans with the majority of our food supply  Formed 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 Selection

First 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

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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 Populations What 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