sources of evidence of evolution

• Sources of Evidence for Evolution

  • Fossil Records
  • Comparative Anatomy
  • Embryonic Development
  • Amino Acid Sequence
• Evolution


  Change in the genetic makeup (and often, the heritable features) of a population over time
• Fossil Records


  • Traces of organisms that lived in the past and were preserved by natural processes
  • Materials used by paleontologists to study earth's history
• Fossil Records


  • Most commonly found on sedimentary rocks
  • Can also be found on ice
  • Fossils can be compressed and imprint
• Compression


  • Compressed is the other side with more organic material
  • Shallow external molds and imprint left by animal or plant tissues with little or no organic materials present
• Determining the age of fossils

  1. Relative dating

  2. Absolute dating
• Relative Dating


  The younger fossils is found on the top layer and the older fossils is found in bottom layer. This is a method used to determine the age of rocks by comparing them with the rocks in the other layers.
• Absolute Dating


  This is another method of determining the age of fossils using radioactive isotopes. This is done by analyzing the age of the fossils and rocks where the fossils were found, using the rate of decay of certain radioactive isotopes.
• Absolute Dating


  • Carbon-14 Dating/Radiocarbon Dating
• Carbon-14 Dating/Radiocarbon Dating


  Scientists determine the age of fossils by checking the amount of radioactive carbon-14 in the fossil. Carbon-14 breaks down or decays to form nitrogen-14. The rate of this decay is constant e.g. half of the remaining carbon-14 breaks down every 5730 years.
• Geologic Time Scale proposes the major events in the earth's history. It also suggests the appearance of various kinds of organisms in a particular period on earth.
• Comparative Anatomy


  The study of the similarities and differences in the anatomy of two species
• Analogous Structure


  Structures of unrelated species may evolve to look alike because the structure is adapted to similar function
• Homologous Structure


  Structures from different species which have similar internal framework, position, and embryonic development
• Basis of Comparison


  • Analogous
  • Homologous
• Divergent Evolution


  The splitting of an ancestral population into two or more sub- populations
• Convergent Evolution


  Convergence is an increase in similarities among species derived from different ancestors because of similar adaptation to similar environment
• Analogous Structure


  • Wings of bats and whales
• Homologous Structure


  • Wings of birds, butterflies and bats
• Embryonic development


  The process through which a fertilized egg becomes an adult organism
• Homologous features


  Structurally similar anatomical features that two species share
• Vertebrates


  Animals that have a backbone or vertebral column
• Similarities in vertebrate embryonic development

  • All vertebrates possess similar structures during their embryonic stage called pharyngeal (or gill) slits, which in fish develop into gills but in other vertebrates either diminish or transform into different structures like parts of the ear or throat
  • Whether it's the forelimbs of a human, the wings of a bird, the flippers of a dolphin, or the arms of a bat, the underlying pattern of limb development is conserved across different vertebrate groups
  • In humans, the tail bud disappears, leaving the coccyx (tailbone). But in aquatic animals like fish and amphibians, the tail bud turns into the tail fin, helping them swim

  
• As an embryo grows, physical structures change (some features become visible, while others disappear)

  
• Homologous structures in embryonic development suggest that ancestral structure was maintained as things diversified

  
• In general, embryos of related species have more features in common at earlier stages of development than they do at later stages

  
• Cytochrome c


  A protein found in the mitochondria of cells, where it plays a crucial role in the electron transport chain, a process essential for generating energy in the form of ATP
• Molecular clocks


  Help figure out when species split apart by looking at how fast proteins change over time. They do this by comparing the differences in protein sequences between species and using a rate of change to estimate how long ago they diverged
• Molecular clocks do not precisely determine evolutionary events
• Cladogram


  A type of diagram that shows the evolutionary relationships between different organisms. It represents the branching pattern of evolutionary history, illustrating how species are related to each other through shared ancestry

  
• Humans and chimpanzees


  • Are like distant cousins. Even though we look different, our proteins, like cytochrome c, hemoglobin, and insulin, are very similar. This shows that we share a common ancestor and are closely related in evolution
• Hippos and whales


  • Are alike in some proteins because they come from the same family tree. Their genes haven't changed much over time, so their proteins have ended up looking and working similarly. This shows up in proteins like cytochrome c and hemoglobin, which do important jobs in cells
• The greater the similarity in amino acid sequence, the closer the relationship of the organisms. The organisms which are similar in structure and also possess similarity at the biochemical level could probably have a common ancestor

  
• Fossils are preserved remains or traces of organisms from past geological periods, providing direct evidence of their existence.