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Evidence of Evolution

The evolution of dogs is described in this evolutionary tree. Time is represented horizontally on the tree. Dogs that are more closely related, like domestic dogs and gray wolves, are closer on the tree. Scientists at the University of California developed this evolutionary tree based on fossil evidence, comparison of modern dogs, and genetic analysis of DNA and proteins.
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National Biological Information Infrastructure

Molecular Evolution

Molecular evolution is the process of how genes in populations of organisms change over time. Techniques to explore genes and chromosomes, such as electrophoresis and DNA and RNA sequencing, allow scientists to compare DNA from different species and figure out evolutionary relationships. Species that have very similar genetic-makeup have a closer evolutionarily relationship.

All living things have DNA. There are differences in DNA of individuals of the same species. There are many more differences in DNA of different species. To deduce evolutionary relationships using DNA, scientists compare the DNA of different species. Species that are very distantly related, such as turtles and bacteria, have different DNA. Species that are more closely related have more similarities in their DNA. For example, 98.7% of human and chimpanzee DNA is the same, indicating a relatively close evolutionary relationship.

Last modified May 16, 2005 by Lisa Gardiner.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF