Evidence Of Evolution

Question 1

How do we know things have
evolved in the past?

Answer 1

➢Fossils
➢Biogeography
➢Anatomy
➢Embryology
➢DNA

Question 2

Fossils

Answer 2

• Fossil - a remnant, impression, or trace of an organism of past geologic ages that has been preserved in the
  earth’s crust

❖Fossils give us a glimpse at the history

Question 3

Fossil Record

Answer 3

*mineralized remains of a living organism

*Age measured:
-Position in rock ( older = deeper)
-Radiometric dating
- decay of radioisotopes in the fossil

*Most recent ancient fossils resemble current living organisms suggests gradual structural changes of a
species occurred over time

Question 4

Transitional Fossils

Answer 4

➢ Fossils that show intermediary links between groups of organisms
➢ Link the past with the present

Question 5

Biogeography

Answer 5

Is the study of the of the past and
present geographical distribution of
organisms

➢ Geographically close environment are more likely to be populated by related species than are locations that are geographically separate but environmentally similar

➢ Organisms living on islands resemble those on the nearby mainland organisms on islands evolve from mainland migrants

Question 6

Anatomy

Answer 6

• Homologous Features
• Structures with similar origin but different functions in modern species
  -Suggests organisms with homologous structures share a common ancestor

*Analogous structures
- A structure that performs similar function but different structure
- Does not show evolutionary relationships between animals but DOES support the idea of natural selection (environment’s influence)

*Vestigial Structures
- Remains of a structure that served a purpose in some ancestor but no longer serve a purpose for the current organism
- Some birds have wings but can’t fly; humans have a tailbone but no tail
* Pelvic bone in Dorudon whale
* Appendix – humans
* Dogs and cats 5th toe

Question 7

Embryology

Answer 7

• Homologous structures also occur in embryos and indicated common ancestral origin
• All vertebrates possess a short bony tail and gill slits in early development

Question 8

DNA

Answer 8

• Comparison of DNA and proteins can show relatedness of organisms
• If two species have similar DNA sequences, these sequences must have been inherited from a common ancestor
• Fewer difference in DNA sequence = More closely related
• With the improvement of molecular technology, more and more evidence mounts to support evolution.
• Almost all living organisms use the same basic biochemical molecules, including DNA, ATP, and many identical or nearly identical enzymes.
• The degree of similarity between DNA base sequences and amino acid sequences in two organisms is thought to indicate their degree of relatedness.