Evolution

• Lamarack

  Jean-Baptiste Lamarck (1744-1829) was a French naturalist and biologist who laid the groundwork for the current theories of evolution. Two Broad Claims: 1. New species evolved from previous species. 2. Acquired traits are inherited by offspring.
• Inheritance via acquired characteristics

  Organisms transform their appearance to produce evolution
• Charlies Darwin's Theory


  • Organisms produce more offspring than can survive in nature, organisms have the ability to produce more offspring than can survive to become adults.
  • Some inherited traits provide organisms with an advantage - some inherited traits give organisms an advantage in coping with environmental challenges. These organisms are more likely to survive longer and produce more offspring; they are "naturally selected for".
  • Each generation contains proportionately more organisms with advantageous traits - because more organisms with advantageous traits have more offspring.
• Natural Selection


  Darwin's theory of natural selection holds that variation within species occurs randomly and that the survival or extinction of each organism is determined by that organism's ability to adapt to its environment.
• Darwin believed that all of the different finches came from a common ancestor and that their differences were a result of natural selection.
• Variation


  a difference in traits between individuals of the same species. Variations in traits are necessary for a population to evolve.
• Genetic Trait


  a feature that is passed down by genes from one generation to the next. Genetic traits are determined by genes in an individual's DNA and are inherited from the individual's parents through reproduction.
• Genetic traits


  • eye colour, Dimples, height
• DNA


  a molecule that stores the genetic information that determines how an organism looks and functions and can only make a difference to the organism's survival if it's expressed in traits.
• Mutation


  small random changes in DNA. Mutations may be harmful, beneficial, or have no impact on the organism's survival. New mutations arise in each generation through reproduction.
• Natural Selection


  • the survival of organisms that are better adapted to their environment. Survival of the fittest - individuals in a population that have inherited traits that help them survive and reproduce
  • The fittest individuals leave more offspring in the next generation than their peers.
  • Over time these fittest individual traits tend to become more common in the next generation.
  • Over generations, the population will become adapted to its environment.
• Frequency of a Trait

  the measure how common a particular trait is within a population. It can be expressed as a percentage of the population. Natural selection leads to changes in the frequency of traits.
• Selective Pressure


  • any challenge that affects an organism's ability to survive in a particular environment.
  • For Example: hunting by predators, access to resources, such as food, shelter, territory and mates, environmental factors, such as temperature and weather conditions, vulnerability to diseases, human activities, such as hunting and pollution.
  • Selection pressures can either increase or decrease the frequency of a genetic trait.
• Adaptation


  Any genetic trait that helps an organism survive in its environment.
• Evolving Adaptations


  • Adaptations help organisms survive and reproduce, but where do they come from? The answer is provided by the theory of evolution by natural selection. To understand how adaptations evolve, analyse the infographic below.
• Types of Adaptations


  • Structural Adaptations - a physical feature of the body
  • Behavioural Adaptations - a behaviour or action
  • Physiological Adaptation - an internal body process
• The Fossil Record

  • Fossils are the first piece of evidence that shows us that life has changed over the history of the Earth.
  • Cladogram - a fossil records maps that show links between organism and their evolutionary pathways.
  • Overtime other characteristics have appeared in common ancestors, which give rise to new groups.
• The Fossil Record


  • Evolution of species can be determined by studying the changes in fossil remains.
• Comparing DNA


  • DNA analysis is another important type of evidence for evolution.
  • An organism's DNA contains the genetic information that determines its genetic traits.
  • As species evolve and adapt to their environment, some parts of their DNA change while others stay the same.
  • the greater the similarity in DNA, the closer the relationship.
• Tree of Life


  • A way of representing the relationships between species is by a tree of life diagram.
  • It shows how species evolved from common ancestors that lived millions of years ago.
  • Shorter branches show types of organisms that have died out.