variation, evolution and more evolution

• Organisms of the same species have differences
• Difference in looks in species in called variation
• What are the two types of variation

  genetic variation

  environmental variation
• Different genes cause..

  genetic variation
• All plants and animals have characteristics that are in some way similar to their parents
• The combining of genes from two parents causes genetic variation, so they are NOT genetically identical
• Identical twins are genetically identical
• Some characteristics are determined only by genes
• Name 3 characteristics that are determined only by genes in animals.

  eye colour

  blood group

  inherited disorders
• Characteristics are also influenced by the..

  environment
• The environment that organisms live and grow in cause differences between members of the same species
• The environment that organisms live and grow in cause differences between members of the same species, what is this called?

  environmental variation
• An example of characteristics influenced by the environment are getting a tan, losing a finger or a plant having yellowing leaves
• Most characteristics are due to genes AND the environment
• An example of characteristics being influenced by both genetic and environmental variation is weight, skin colour, height and academic prowess
• Mutations are changes to the sequences of bases in DNA
• What is the theory of evolution?

  That all of todays species have evolved from simple life forms that first started to develop over 3 billion years ago
• only the fittest survive..

  said charles darwin my hero
• Organisms need to compete for limited resources in an ecosystem
• Darwin concluded that organisms with the most suitable characteristics for the environment would be..


  more likely to survive
• The idea that organisms with characteristics more suitable to their environment would survive compared to those who didn't is called..


  survival of the fittest
• Organisms that survive are more likely to..

  reproduce and pass on genes that made them successful at living and not dying
• less well adapted organisms are less likely to survive so they wouldnt..


  reproduce
• overtime more beneficial characteristics become..

  more common and the species changes
• The development of a new species is called speciation
• After a long period of time and lots of natural selection the phenotype of organisms can change drastically to the point where a new species is formed. This is called..


  speciation
• Speciation happens when populations of the same species change enough to become..


  reproductively isolated
• What does reproductively isolated mean?

  that they can't interbreed to produce fertile offspring
• Extinction is when no individuals of a species..


  remain
• Species become extinct becuse of:

  the environment changing too quickly (e.g destruction of habitat)

  a new predator kills them all

  a new disease kills them all

  they can't compete with another species for food

  a catastrophic event happens that kills them all (e.g volcanic eruption)
• Darwin couldn't explain why the characteristics appeared or how they were passed on so people were sceptical
• Jean-Baptiste Lamarck thought that changes that an organism acquires during it's lifetime will be passed on to it's offspring and inherit the characteristic e.g dying hair purple will be passed on
• Scientists developed different hypotheses from observations
• Lamarcks hypothesis was rejected because he didn't have any evidence or experiments to support his claim
• The discovery of genetics supported Darwins idea so it was accepted
• Evidence for Darwins theory can also be found in fossils and resistant bacteria