5______________________of Evidence for the Theory of Evolution
61.____________ Evidence of Evolution FossilsRock fossils are created when three events occurorganism buried in sedimentcalcium in bone or other hard tissue mineralizessurrounding sediment hardens to form rock
7Fossil Evidence of Evolution Absolute dating:Relative dating:Isotopes, like U238, transform at precisely known rates into nonradioactive forms.The rate of decay is known as an isotope’s half-life
9Fossil Evidence of Evolution recordsdocumentthe courseof life throughtime
10Fossil Evidence of Evolution FossilsThe oldest known bird fossil is theIt is intermediate between bird and dinosaurPossesses some ancestral traits and some traits of present day birdsArchaeopteryx was first found in 1859
11Fossil Evidence of Evolution Fossil of Archaeopteryx
12Fossil Evidence of Evolution Recent discoveriesFour-legged aquatic mammalImportant link in the evolution of whales and dolphins from land-dwelling, hoofed ancestorsFossil snake with legsTiktaalik: a species that bridged the gap between fish and the first amphibianOysters: small curved shells to large flat shells
13Fossil Evidence of Evolution Whale “missing links”
14Fossil Evidence of Evolution Evolutionary change in body size and toe reduction of horses
15HOMOLOGOUS STRUCTURESimilar features that originate in a shared ancestor (derive from same embryonic structure)Can result from modifications that change an original feature to 2 extremely different types (wing and arm)Homologous structures
16Anatomical Evidence for Evolution 2. Homologous structures:structures with common evolutionary origins (can be similar in structure, function, or both)The bones in the forelimb of mammals are homologous structuresDifferent functions, same ancestor structure
17Anatomical Evidence for Evolution Homology of the bones of the forelimb of mammals
18ANALAGOUS FEATURE Serve identical functions and look similar No anatomical/embryological similarityWing developed independently and differently in more-recent ancestors of each animal3. Analogous structures:
19Anatomical Evidence for Evolution Vestigial structures:Vestigial structures of a whale: hind leg bones!?
204. Vestigial Structures Humans Muscles for wiggling ears (similar muscles that animals use to move ears to hear predators or prey)Tail bones present in human and all vertebrate embryos. In humans, the tail is reduced; most adults only have three to five tiny tail bones and, occasionally, a trace of a tail-extending muscle.Appendix Structure which presumably had a digestive function in some of our ancestors, like the cecum of some herbivores. In humans, it varies in length from 5–15 cm, and some people are born without one.
21Vestigial Structures cont. Wisdom teeth There are two possible reasons why the wisdom teeth have become vestigial. The first is that the human jaw has become smaller than its ancestors -and the wisdom teeth are trying to grow into a jaw that is much too small. The second reason may have to do with dental hygiene. A few thousand years ago, it might be common for an 18 year old man to have lost several, probably most, of his teeth, and the incoming wisdom teeth would prove useful. Now that humans brush their teeth twice a day, it's possible to keep one's teeth for a lifetime. The drawback is that the wisdom teeth still want to come in, and when they do, they usually need to be extracted to prevent any serious pain.
22Vestigial Structures cont. Pythonshave tiny femurs (leg bone)ManateesFingernails on their finsBlind cave fishNonfunctional eyes
23Anatomical Evidence for Evolution Strongest anatomical evidence supporting evolution comes from comparisons of how organisms develop.Early vertebrate embryos possess pharyngeal pouches (gill slits) that develop into:In humans: glands and ductsIn fish: gills
245. ________________ Evidence for Evolution Developmental similarities reflect descent from a common ancestor
266.AllTwo closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences.This also gives evidence of a common ancestor.
27Convergent EvolutionBiogeography: the study of the geographic distribution of speciesSome plants and animals have similar appearance but are only distantly relatedConvergent evolution: the independent development of similar structures in organisms that are not directly relatedConvergent evolution is usually seen in animals and plants that live in similar environments
28Convergent Evolution Marsupials and placentals Marsupials: young are born in an immature condition and held in a pouch until they developPlacentals: young are not born until they can safely survive in the external environment