Biology

 List 2 pieces of evidence for evoluthttps 

 Fossil Record  Geographic Distribution  Similarities in Structure  Similarities in Development  Molecular Biology

 Fossils = preserved remains or markings left by organism that lived in the past  Found in sedimentary rock  Buildup of sand and silt over long period of time  Deposited by rivers and compress sediment below

 Aquatic organism  Sink to bottom and are buried in sediment  Land organism  Swept into rivers, lakes or swamps  Others covered by dust, sand or volcanic ash

 Rock layers  Younger rock strata on top of older ones  Position of fossils with the layers determine relative age  Chronological record life’s remains

 Provides evidence of Earth’s changing life  Oldest fossil evidence = chemical traces in rocks 3.8 billion years old  Prokaryotes (bacteria & archaebacterial) have been found in rocks 3.5 billion years old  Data fits with evidence that prokaryotes are the oldest life forms  Younger fossils record evidence of eukaryotic organisms

 Fossils provide evidence to link past to present  Ex: Whales evolved from land-dwelling ancestors that had 4 limbs

 Darwin noted that there are similarities and differences among species located in different parts of the world  Suggests these organism evolved from common ancestor

 Why do some species share similar characteristic to other species found in a different ecosystem  Why are there so many marsupials in Australia verses placental animals

 Just as fossil records provide evidence to the past Geographic distribution provides clues to how organisms may have evolved

 Similarities in structure among species provide clues to evolutionary history  Forelimb of mammals consist of same skeletal parts  Same parts but different functions  Called homologous structures

 Homologous structures = similar structures in species that share a common ancestor

 Homologous structures provide evidence that evolution is a remodeling process  Structures that functioned one way in an ancestral species changes over time as it takes on new functions  Darwin called this “descent with modification”

 Vestigial structures  Are remnants of structures that may have had important functions in ancestral species but no clear function today’s species  Goosebumps  Dewclaws in dogs and cats  Appendix

 Development of organisms and the similarities provide clues to evolutionary history  Embryos of similar closely related organisms have similar stages of development  Supports homologous structures

 DNA sequencing  Reading genetic codes enable closer comparison of organism  The more similarities or matches the closer the organisms are related  The more differences among the DNA sequence the less related and less likely they share a common ancestor

Evidence for Evolution Fossil Rec ord Geogra phic distributi on Similari ities of Struct ure Similarii ties in Develo p-ment Molec ular Biolog y