Covers the entire section on Evolution in Present Times. Includes notes from the textbook, as well as additional class, video and research information, diagrams and practice questions.
Applicable to all IEB Grade 12s.
Written by a 90% < student.
Evolution in present times
Evolutionary principles have become very relevant and used in:
- Resolving legal issues, by ‘DNA fingerprinting’
- Tracing evolutionary origins of diseases and developing treatments
- Selective breeding of plants and animals
- Understanding resistance of insect pests to insecticides
- Modern warfare, by the use of biological pathogens and mutation-inducing chemicals
Evolution is always happening, but for many species, including humans, it occurs extremely very
slowly. This makes it very difficult to observe.
However, evolutionary change can be:
- Demonstrated in a lab using rapidly reproducing life forms such as single-celled organisms and
- certain invertebrates.
- Seen as a result of breeding the new varieties of plants and animals by artificial selection.
- Noticed in a situation where resistance to TB drugs developed in the TB bacterium.
- Noticed in a situation where resistance to an insecticide developed in insects.
- Seen in alarming adaptation of HIV drugs.
- Shown by development of new species of plants by polyploidy and hybridization.
Why the use of antibiotics and insecticides can be risky
Populations of pathogenic organisms, such as bacteria and insects, can evolve quickly as:
- They have natural variation
- Mutations occur often because the individuals breed very rapidly
In the process of evolving they can gain resistance to many chemicals that should kill them.
The antibiotics or insecticides therefore cease to be useful.
Example 1: Resistance to antibiotics in bacteria
Example 2: Resistance to insecticides in pest insects
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