Evidence Supporting Evolutionary Theory • Fossil Record • Biogeography • Homologies • Anatomical- Homologous structures • Anatomical- Vestigial structures • Molecular- DNA Similarities in the genetic code • Developmental- Embryology
Fossils Remains, impression, tracks or other evidence of an organism that lived long ago Most fossils are found in layered sedimentary rock. Newest fossils are at the top. Oldest fossils are at the bottom. Ancient shrimp fossil A shrimp today
Biogeography • Scientists can study the distribution of species to help them determine evolutionary relationships. • Species that evolved from a common ancestor are usually found geographically near each other. • Just because two ecosystems are very similar, it doesn’t mean you will find the same species inhabiting it. What is it? Patterns in the diversity and distribution of species. Why are there penguins found in Australia, Chile, and South Africa? The continental drift theory, first proposed by Alfred Wegener in 1912, has been supported by oceanographic evidence. Continental drift has also influenced the distribution of species. Arctic Antarctic Why aren’t they found in both places?
Anatomical Homologies Homologous structuresStructures that share a common ancestor may have the same anatomical structure but may have adapted in ways that enable the organism to survive in different environments.
Turtle Bird Alligator Mammal Anatomical similarities Some organisms may not look alike, but they’re built alike Homologous structures show evidence of: -similar genes -common ancestor
Homologous Structures Turtle Alligator Bird Horse common ancestor
Vestigial Structures • Body parts and organs that arereduced (smaller) in size and haveno benefit, but are still present in the body. Ostrich with wings Blind cave salamander and blind cave fish
DNA The genetic material of some organisms is very similar. DNA sequences that are very similar tell us the organisms originate from a common ancestor. When they are very different, we know the organisms are not related. Amino acids are coded by DNA. Amino Acid Difference in Hemoglobin Compared with Human
The chart below shows the amino acid sequence for cytochrome-c of five vertebrates. 1. Compare the amino acid sequence of human cytochrome-c with that of the other four vertebrates.
DNA DNA directs the assembly of amino acids into specific proteins; therefore, species that shared a common ancestor more recently have fewer amino acid differences. Hemoglobin Comparison Amino acid differences from HUMANhemoglobin protein Species Lamprey eel 125 Frog 67 Chicken 45 Mouse 27 Rhesus monkey 8 Gorilla 1
Embryology The similarities between the development and growth of a fertilized egg cell. Embryos of different species may appear similar in early stages of development Bird embryo Human embryo
Embryo Development click here