Evidence for evolution - AP BIOLOGY WITH MRS. HAAS · Evidence for Evolution . Why do we not find...
Transcript of Evidence for evolution - AP BIOLOGY WITH MRS. HAAS · Evidence for Evolution . Why do we not find...
Evidence for evolution
• biogeography
• fossil record
• comparative anatomy
• homologous structures
• vestigial structures
• comparative embryology
• similar biochemistry = DNA and protein
Fossil Record
• Shows the history of life on Earth and how different groups of organisms have changed over time
Relative Dating
• Can determine a fossil’s relative age
• Performed by estimating fossil age compared with that of other fossils
• Drawbacks- provides no info about age in years
Absolute Dating
• Can determine the absolute age in numbers
• Is performed by radioactive dating- based on the amount of remaining radioactive isotope
• Drawbacks- part of the fossil is destroyed during the test
Homologous Structures
• Same/similar structure in a different species due to common ancestor
• Different function
Vestigial Structures
• Traces of homologous organs in other species; functionless in some
• Often small in size than original
• Ex. appendix, hip bones in pythons, pelvic bones in whales
Comparative Embryology
Comparative Embryology
• Comparing species in early stages of development can show evidence of common ancestry
Comparative Biochemistry
• Compare DNA and proteins of different species for level of similarities/differences
• More DNA similarities = more recent common ancestor
Comparative Biochemistry
Convergent evolution; analogous structures
• Convergent Evolution: Non-related organisms evolve to have similar traits by adapting to similar environments
• The result is analogous structures
• Structures that have similar function, but do not show relatedness
• Ex. fins in fish and dolphins
Evidence for Evolution
Why do we not find evidence of gradual change between species?
Stephen jay gould 1941-2002
punctuated equilibrium
similar to Darwin except in timing
Believed population only changes when
forces by environment
Rest of time in equilibrium