Evolution - B1

Evolution - B1

1. Particular genes or accidental changes in the genes of plants or animal may give them characteristics that enable them to survive better.

   • over time this may result in entirely new species

2. there are different theories of evolution

   • DARWIN'S THEORY
     • THE MOST WIDELY ACCEPTED
     • natural selection
       • states that all species of living things have evolved from simple life forms that first developed more than 3 billion years ago
       • this is a theory because of the timescales involved it is unlikely to ever be proven
       • evolution occurs via this process
         • - individuals within a species may show a wide range of variation because of differences in their genes
         • - individuals with characteristics most suited to the environment are more likely to survive and breed successfully
         • - those genes are responsible for the survival characteristics are then passed down to the next generation
     • many people refused to accept his theory because:
       • - it was a conflict with religious views that God had created the universe and all creatures in it
       • - there was insufficient evidence to support the theory
         • Darwin had developed his ideas from finches on the Galapagos islands; little research had taken place
       • - the mechanisms of inheritance and genes were not known
   • LAMARCK'S THEORY
     • worked before Darwin's
     • based on the idea that changes occur in an organism during its lifetime can be inherited
       • in the vast majority of cases, this type of inheritance cannot occur
     • Lamarck thought herons had evolved long legs because they stretched their legs to stay dry, as shown
       • they would then pass on these characteristics to their offspring

3. CLASSIFICATION

   • evolution and patterns of change can be studied efficiently only if organisms are carefully defined and their relationships understood
     • living organisms are classified into:
       • ANIMALS
       • PLANTS
       • MICROORGANISMS

4. MUTATIONS

   • = *random genetic alterations
   • they can cause an extreme change in the characteristics of an organism
   • if the mutation is coupled with a change in the environment... there can be relatively rapid change in that species

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