Evolution Change over time

More info about Evolution Evolution is a gradual change in the characteristics of a species over time. The structures, behaviors, interactions, and internal processes observed in the millions of species on this planet are the result of the process of evolution. Charles Darwin stated that evolution by the process of natural selection explained how populations of organisms evolve.

Evidence to support evolution include: Molecular Homology Developmental Homology Anatomical Homology Fossils Biogeography

Molecular Homology: by comparing the DNA sequences of two organisms or the amino acid sequences made from the DNA, scientists can learn which organisms are related; the more DNA two organisms have in common, the closer related they are Using the table, compare the amino acid sequence of the chimp and the human. Notice that for this protein the chimp and human have the exact same sequence. Now compare the baboon and the human. Notice that there are 5 differences in the sequence. This tells you that the human is more closely related to the chimp than the baboon.

2. Developmental Homology Similarity in embryo development shows a close relationship (vertebrate embryos all have tail & gill slits)

3. Anatomical Homology An inherited trait that increases the population’s chances of survival and reproduction is an adaptation

Homologous Structures: structure with different functions found in different species and thought to be inherited from common ancestors ex: whales, cats and birds all have the same # and type of bones in the forelimbs but their functions are different

Analogous Structures: have the different structures but the same function & do not show a close relationship ex: insect wing and bird's wing

4. Fossils These are imprints or remains of living things. In undisturbed layers of sedimentary rock, the deeper it is, the older it is. Give us information about extinct species.

5. Biogeography Marsupials are found in the Americas as well as Australia and New Guinea, shown in orange on the map at right. There appear to be no routes of migration between the two populations. How could marsupials have gotten from their place of origin to locations half a world away?

Biogeography Fossils of marsupials have been found in the Antarctic as well as in South America and Australia. Scientists have demonstrated that what is now called South America was part of a large land mass called Gondwana, which included Australia and Antarctica. Marsupials didn't need a migration route from one part of the world to another; they rode the continents to their present positions.