Evolution and speciation: Inheritance, variation and evolution: Biology: GCSE (9:1)

• Genetic variation


  Variation in an individual is caused primarily by genetic changes that result from mutations or the inheritance of reshuffled genetic information via meiosis

  
• Variation in a population


  Individual organisms within a particular species show a wide range of variation for a characteristic

  
• Survival of the fittest

  Individuals with characteristics most suited to the environment are more likely to survive and breed successfully

  
• Inheritance of characteristics


  The characteristics that have enabled certain individuals to survive are then passed on to the next generation

  
• Natural selection


  A process where individuals in a population display variations that put them at a biological advantage, increasing the chances that these individuals will successfully reproduce and pass on their adaptive traits

  
• Evolution


  A change in the inherited characteristics of a population over time through the process of natural selection, can result in speciation

  
• Speciation


  An outcome of evolution and isolation, where two populations of a species become so distinct they can no longer interbreed to produce fertile offspring

  
• Geographical isolation

  Where two distinct populations of a species are unable to interbreed due to separation by a physical barrier such as a body of water or geological structure

  
• Reproductive isolation


  Where two distinct populations are unable to interbreed due to incompatible courtship behaviour, seasonal activity or structural and biological incompatibility

  
• Charles Darwin


  The famous naturalist who proposed the theory of evolution by natural selection, as a result of years of observations and research

  
• HMS Beagle


  The ship used by Charles Darwin on his voyages around the world, Darwin made some very important observations on his round the world expedition

  
• Galapagos islands


  A cluster of islands in the Pacific Ocean, Darwin observed a number of unique species that had adapted to each island such as the Galapagos finches and tortoises

  
• On the Origin of Species

  Darwin published his research, findings and ideas in this famous work of scientific literature in 1859

  
• Controversy

  Darwin's scientific literature was considered controversial as it contained many revolutionary ideas and took a long time to be gradually accepted

  
• Gradually accepted theory

  The theory of evolution by natural selection was gradually accepted because it challenged ideas about God and creationism and there was insufficient evidence at the time
• Developments in the theory of evolution

  There was limited evidence for evolution at the time when it was first described, however the relevant mechanisms of variation and inheritance were better understood 50 years later
• Jean-Baptiste Lamarck


  A french naturalist who suggested the mostly-invalid theory now known as Lamarckism, where changes that occur in an organism during its life can be inherited

  
• Alfred Russel Wallace

  Independently proposed the theory of evolution by natural selection at a similar time as Darwin, following significant research and observations in Southeast Asia

  
• Wallace's research


  Wallace is known for his work on speciation and warning colouration, as well as his work on the theory of evolution by natural selection

  
• Joint publication

  Darwin and Wallace published their work on evolution together in 1858, which prompted Darwin to publish On the Origin of Species a year later
• Warning colouration

  Wallace noticed a number of species can deter predators by displaying colours and patterns to suggest they are dangerous

  
• Mimicry


  Many species can display false warning colouration where they pretend to be another species that is poisonous, venomous or otherwise threatening