 A hypothetical trace of evolution ◦ One original common ancestor  Scientists use both morphology and genetics to produce phylogenic trees ◦ Morphology- share similar physical characteristics ◦ Analysis of genetic similarity

 the study of the body structures in different organisms ◦ anatomical similarities gives evidence of a common ancestor Human Dog Seal

 Structures that are similar but has different functions ◦ Shows common ancestry

 Acquiring the same biological trait independently  Example: Flight  Humming bird and moth - last common ancestor did not have wings  They acquired these traits separately ◦ Only very few designs for a wing would allow for hovering

 Similar functions but differ in structure ◦ Ex: wings of a hummingbird and humming moth – both can hover to feed

 Two or more related populations or species become more and more dissimilar.  Divergence is nearly always a response to differing habitats and can result in new species

◦ Many related species evolve from a single ancestral species ex: Galapagos finches

 Features that were useful to an ancestor, but they are not useful to the modern organism that has th. ◦ tailbone in humans ◦ Appendix ◦ Some snakes have tiny pelvic bones and limb bones

 Closely related organisms often have similar stages in their embryonic development ◦ All vertebrate embryos are similar ◦ Vertebrates share a common ancestor lemurpig human

 All organisms share related biochemical processes: ◦ All cells use DNA as genetic blueprint ◦ All use RNA, ribosomes, and approximately the same genetic code for translation ◦ All use roughly the same set of 20 amino acids to build proteins ◦ All use ATP to transfer energy

 the DNA nucleotide sequence of the human and mouse cytochrome c gene is very similar, suggesting shared ancestry

