WHAT ARE THE EVIDENCES FOR EVOLUTION? NEET (part-2)




Biochemical similarities: 

  • In the same line of argument, similarities in proteins and genes performing a given function among diverse organisms give clues to common ancestry. 
  • These biochemical similarities point to the same shared ancestry as structural similarities among diverse organisms. 

Anthropogenic: 
  • Man has bred selected plants and animals for agriculture, horticulture, sport or security. Man has domesticated many wild animals and crops. 
  • This intensive breeding programme has created breeds that differ from other breeds (e.g., dogs) but still are of the same group. 
  • It is argued that if within hundreds of years, man could create new breeds, could not nature have done the same over millions of years?

Evidences from embryology: (Von Baer's Principles)

  •  The embryo of a given species does resemble the embryonic form of a lower one
  •  The embryo of a given species never resembles the adult form of a lower one.
  • More specialized characters develop from the more general ones.
  • The general features appear earlier in development than do the specialized features.
  •  Johann Friedrich Meckel: "recapitulation theory" or "Ontogeny recapitulates phylogeny"
  • Earnst Haeckel: Biogenetic law.
  • example-1: the tadpole larve of amphians resembles with fish. this indicates that the amphibians might have evolved from fish
  • example-2: heart of vertebrates 
ADAPTIVE RADIATION
  • During his journey Darwin went to Galapagos Islands. 
  • There he observed an amazing diversity of creatures. 
  • Of particular interest, small black birds later called Darwin’s Finches amazed him. 
  • He realised that there were many varieties of finches in the same island. 
  • All the varieties, he conjectured, evolved on the island itself. From the original seed-eating features, many other forms with altered beaks arose, enabling them to become insectivorous and vegetarian finches. 
Adaptation in Darwins Finches
  • This process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation.
  • Darwin’s finches represent one of the best examples of this phenomenon. Another example is Australian marsupials. 
  • A number of marsupials, each different from the other evolved from an ancestral stock, but all within the Australian island continent. 
  • When more than one adaptive radiation appeared to have occurred in an isolated geographical area (representing different habitats), one can call this convergent evolution. 
  • Placental mammals in Australia also exhibit adaptive radiation in evolving into varieties of such placental mammals each of which appears to be ‘similar’ to a corresponding marsupial (e.g., Placental wolf and Tasmanian wolf-marsupial).

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