Evolution

• Evolution is a change in the inherited characteristics of a population over time through natural selection, which may result in a new species.
• The theory of evolution by natural selection is the theory that the organisms that are best adapted to their environment are most likely to survive and pass on these characteristics to their offspring.
• Evidence supporting the theory of evolution:

  Parents pass on their characteristics to offspring in genes.

  Fossil record evidence.

  Evolution of antibiotic-resistant bacteria.
• Fossils are remains of organisms from millions of years ago found in rocks.
• Fossils might be formed by:

  Parts of an organism do not decay because the conditions needed for decay are absent.

  Traces of organisms are preserved.

  Parts of an organism are replaced by minerals.
• The benefits of fossil record are that we can learn how species changed and how life developed on earth and can track the movement of species across the world.
• The problems with fossil record are:

  Many early organisms were soft-bodied so left few fossils.

  Gaps in the fossil record as not all fossils have been found and some have been destroyed.
• Extinction is when no individuals of a species are still alive.
• Factors contributing to extinction include:

  Predators.

  Diseases or pathogens.

  Competition for resources or mates.

  Catastrophic events.

  Changes in the habitat.
• The binomial system is the naming of organisms by their genus and species.
• Carl Woese introduced the classification system using a three-domain system of Archaea, Bacteria and Eukaryota.
• Bacteria can evolve rapidly because they can reproduce at a fast rate.
• Antibiotic-resistant strains of bacteria develop by mutations that allow the strain to survive and reproduce in the presence of the antibiotic.