evidence of evolution

Evidence of Evolution

The Fossil Record, Anatomy and Development, Biological

Molecules

Fossils

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Fossils

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Fossils

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Fossils

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Fossils

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Fossils

What is a fossil exactly?Fossil: any remains, impression, or trace of a living thing of a former geologic age, as a skeleton, footprint, etc.

How is the fossil record evidence for evolution?

Provide actual record of Earth’s past life-formsShows a patern of development from early ancestors to modern descendantsCan predict intermediaries between similar living organisms

Fossils

Formation of fossilsMany species have lived in environments were fossils do not formFossil formation are most likely found in wetlands, slow-moving streams, shallow seas, lakes, and near volcanoesChances are slim that fossilization will occur even in an area where fossils are likely to form, it could be eaten or scattered by scavengers and some bodies decay faster than others

Fossils

Although the fossil record will never be complete, it presents strong evidence that evolution has taken place

Paleontologists (scientists who study fossils) can date fossils accurately using radiometric dating, enabling them to arrange fossils from oldest to youngest

When this is done, orderly patterns of evolution can be seen

Fossils

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Fossils

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Anatomy and Development

Comparisons of the anatomy of different types of organisms often reveal basic similarities in body structures even though the structure’s functions may differ between organisms

Homologous structures: structures that share a common ancestry.

Anatomy and Development

Can be seen in the development of embryos

At some point in development all vertebrate embryos have a tail, and buds that become limbs

Anatomy and Development

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Anatomy and Development

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Biological Molecules

Today with advances in bio-technology, we can test our scientific predictions

If species have changed over time as the fossil record indicates, then the genes that determine the species’ characteristics should also have changed by mutation and selection

Biological Molecules

As species evolved, one change after another should have become part of their genetic instructions, therefore more and more changes in a gene’s nucleotide sequence should build up over time

Biological Molecules

Proteins- this prediction was first tested by analyzing the amino acid sequences or similar proteins found in several species

If evolution has taken place, the species descended from a recent common ancestor should have fewer amino acid differences between proteins than species with shared ancestory at a distant pastComparing one human hemoglobin protein with same hemoglobin of another species reveals a predicted pattern

Biological Molecules

Nucleic Acids- nucleotide changes cause changes in amino acid sequence of protein

Scientists evaluate number of changes and can hypothesize about how organisms are related through evolution

These relationships tend to reflect the relationships indicated by the fossil record