Evolution and Natural Selection

• One evidence of evolution is the comparative anatomy. This evidence focused primarily on the homologous structures.
• Homologous structures 


  are same body structures but have different functions.
• Charles Darwin and the Theory of Evolution

  • Worked with Alfred Russel Wallace
  • Sailed aboard the HMS Beagle
  • Greatly contributed to the theory of evolution
• Darwin's theory of evolution's 3 major ideas:

  • Species undergo a series of changes over time and space. The living individuals of certain species today differ from those that have lived in the recent past.
  • All organisms share common ancestors with other species. Over time, adaptations result in species with different characteristics.
  • Evolution happens gradually, and this is demonstrated by the sustained events of slow changes observed from various fossil records of organisms.
• All organisms share common ancestors with other species. Over time, adaptations result in species with different characteristics.

  • An example is that humans sharing common ancestors with chimpanzees, common ancestors with whales about 60 million years ago.
• Common Ancestry


  Organisms share a common ancestor.

  
• Gradualism


  Changes happen gradually.

  
• Natural Selection


  is the principal reason for the evolution of organisms.
• "survival of the fittest"


  triggers the gradual changes in the traits of organisms from generation to generation until new characters or traits are lost or created.
• Darwin was able to formulate his theory by observing the variation in beaks of finches, a type of bird in the Galapagos Islands. The modifications in their beaks was a form of evolutionary change to aid in food gathering.
• Adaptive Radiation


  when an organism in different species gives rise to numerous other forms wherein an ancestral species gives rise to multiple other forms because of causes like environmental changes.
• Types of Evolution

  • divergent
  • convergent
  • parallel evolution.
• Divergent Evolution

  • occurs when one species gives rise to more species because of many factors
  • these factors can include the isolation of populations, changes in abiotic conditions, and more.
• Examples of Divergent Evolution

  • Divergent evolution is seen in the distant ancestors of whales
  • These distant ancestors gave rise to multiple “branches” of the whale family tree. One of these branches evolved into the ancestors of dolphins and whales.
  • Adaptive radiation
• Convergent Evolution


  occurs when organisms that are not necessarily related develop characteristics that are similar to each other due to a similarity in environmental conditions.
• Examples of Convergent Evolution

  • Milkfish - which is a species of bony fish
  • Dolphins - are mammals
  • The evolution of fish is largely thanks to the similarity of the environment that fishes and dolphins share, which is an aquatic habitat.
• Parallel Evolution

  • Closely related to convergent evolution, this occurs when a population of the same species is split into two, with both populations being different but still developing very similar characteristics.
  • This could be due to a similarity in the environments that they reside in.
• Types of Evolution

  A) Divergent

  B) Convergent

  C) Parallel

  
• Adaptation 

  • is a process of developing and adopting traits that serve functional roles in an organism
  • These traits are preserved and may evolve through natural selection
  • is when an organism possesses traits that can help it survive in a certain environment.
  • For example, several adaptations that bees have allow them to pollinate flowers while gathering food.
• Adaptation in organisms can be exhibited in two changes:

  • biological
  • evolutionary
• Biological change

  • is the progressive development in physical and functional aspects of an organism during its entire life span.
  • This is often regulated by its genetic make-up that is translated into functioning phenotypes. Biological change is evident in our daily living.
  • An example of biological change in a process for respiration, where the body removes water in the form of sweat for temperature regulation. These sets of biological changes in organisms can be transferred from parent to offspring.
• Evolutionary change

  • the change in heritable traits of an organism through successive generations
  • gives rise to the addition or deletion of traits that create diversity among organisms.
  • These changes require time and can only be observed in comparing several generations of species.
• Fill in each blank with the term or phrase that will complete the statements.

  1. Charles Darwin was an English biologist who is well known for introducing the concept of evolution.
  2. Alfred Russel Wallace felt the same for explaining evolution through natural selection.
  3. Natural selection is the principal reason for the evolution of organisms.
  4. Natural selection is also known as survival of the fittest.
  5. Darwin observed the beaks of finches in Galapagos Islands.