analogy

Examples of analogy in the following topics:

• Distinguishing between Similar Traits

  • These are called analogous structures .
  • Similar traits can be either homologous or analogous.
  • These structures are not analogous.
  • The wings of a butterfly and the wings of a bird are analogous, but not homologous.
  • Some structures are both analogous and homologous: the wings of a bird and the wings of a bat are both homologous and analogous.

• Homologous Structures

  • Bat wings and bird wings evolved independently and are considered analogous structures.
  • In the above example, the bird and bat wings are analogous as wings, but homologous as forelimbs because the organ served as a forearm (not a wing) in the last common ancestor of tetrapods.
  • Although analogous characteristics are superficially similar, they are not homologous because they are phylogenetically independent.
  • The wings of a maple seed and the wings of an albatross are analogous but not homologous (they both allow the organism to travel on the wind, but they didn't both develop from the same structure).
  • The wings of pterosaurs (1), bats (2), and birds (3) are analogous as wings, but homologous as forelimbs.

• Convergent Evolution

  • Traits arising through convergent evolution are analogous structures, in contrast to homologous structures, which have a common origin, but not necessarily similar function.
  • The British anatomist Richard Owen was the first scientist to recognize the fundamental difference between analogies and homologies.
  • Bat and pterosaur wings are an example of analogous structures, while the bat wing is homologous to human and other mammal forearms, sharing an ancestral state despite serving different functions.

• The Role of the Circulatory System

• Building Phylogenetic Trees

  • After the homologous and analogous traits are sorted, scientists often organize the homologous traits using a system called cladistics.
  • Trying to decipher the proper connections, especially given the presence of homologies and analogies, makes the task of building an accurate tree of life extraordinarily difficult.

• Meristems

  • In that sense, the meristematic cells are frequently compared to the stem cells in animals, which have an analogous behavior and function.

• Denaturation and Protein Folding

  • (Bottom) A paperclip analogy visualizes the process: when cross-linked, paperclips ('amino acids') no longer move freely; their structure is rearranged and 'denatured'.

• Introduction to Meiosis

  • Because the events that occur during each of the division stages are analogous to the events of mitosis, the same stage names are assigned.

• What is Evolution?

  • The greater age of the earth proposed by Lyell supported the gradual evolution that Darwin proposed, and the slow process of geological change provided an analogy for the gradual change in species.

• Web, Network, and Ring of Life Models

  • In an effort to save the tree analogy, some have proposed using the Ficus tree with its multiple trunks as a phylogenetic tree to represent the evolutionary role for HGT .