BIOL 3350 1st Edition Lecture 3Outline of Last Lecture I. Evidence exists for change in the eartha. Geologyb. Stratigraphyc. Principle of superpositiond. Principle of cross-cutting relationshipse. Principle of faunal successionf. Cladogramsg. Radiometric Datingh. Phylogenies reconstruct evolutionary historyi. Understanding the origin of key innovationsj. Hypothesis of the evolution of feathers starting in theropodsk. Early hypotheses to explain changes in earthOutline of Current Lecture I. Radiometric DatingII. Geological Time Scale OrderIII. Evidence from the Fossil RecordIV. The Law of SuccessionV. Transitional FormsVI. Evidence from Common AncestryVII. Evolutionary change can create new speciesCurrent LectureVIII. Radiometric DatingThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Potassium-Argoni. Volcanic rocksii. As the volcanic ash cools, the radioactive potassium begins to decay into argoniii. Different isotopes decay at different rates and, therefore, can be used to date rocks of different agesiv. Uranium lead method – dating something very oldv. Carbon-14 – more recent vi. Relative proportions of radioactive potassium and argon in the rock shows how old the rock isb. Carbon-14i. Carbon isotopesii. C-14 is radioactive and decays at a constant rate iii. N-14 replaces C-14iv. Ratio of carbon seen in a living organism is reflective of carbon in the atmospherev. But when the organism dies, it isn’t taking in any more carbonvi. Ratio of carbon to nitrogen in dead animal can show how long ago it diedvii. If no carbon left and only nitrogen, then the organism died a long time ago because all of the carbon has escapedIX. Geological Time Scale Ordera. By Hutton and Lyellb. Ages added later through radiometric datingX. Evidence from the Fossil Recorda. The fact of extinctionb. Cuvier (had the idea of Catastrophism)i. Description of fossil extinct Irish Elkii. Extinct species are relatives of living species found todayiii. Darwin did not agree with his idea of CatastrophismXI. The Law of Successiona. Close relationship between fossil and extant species from the same geographic areab. Close relationship between fossil forms in adjacent rock stratac. Examined trilobites and noticed that trilobites that were the most similar were location in layers (strata) next to each other d. 99% of all species that ever existed on Earth are now extincte. Most of those extinct species disappeared in a slow trickle = “background extinctions”f. Life’s history has been marked by both catastrophic extinction events and constant background extinctionXII. Transitional Formsa. Contain characteristics of ancestral species as well as novel traits of descendant speciesb. By looking at the order of species, we can see how whales transitional from a terrestrial ancestor to a the modern day, totally aquatic whalec. Femur/pelvis left over in whales is a vestigial structure from its ancestord. Transitional forms can show how taxa have changed over evolutionary timee. Mammals swim by undulating spines (like otters and whales in water and land animals running) unlike fish/sharks that flex spine side to sidef. Tiktaalik demonstrates part of the transition from an aquatic fish to a land animalg. Still has fins with radial bones giving structure to fin, but has bones that are homologous to wrist bones of land animalsh. Had a neck (like land animals and not fish)XIII. Evidence from Common Ancestrya. Homology suggest common ancestryb. Embryos in early stage of development could provide evidence of ancestry between organismsc. Embryos of humans show gill splits (our early ancestors were aquatic)d. Tails in embryos of humanse. Analogous structures have a common function but not a common embryonic origini. Ex: wings of birds and insectsf. Homologous structures have a common embryonic origin but may or may not have a common functioni. Ex: wings of birds and batsg. Convergent natural selection leads to analogous body formsi. Shark & whale - the way their bodies are put together has arrived to this state via a different means1. Similar function but not the same common ancestry for that streamline shapeh. Homologies that are not analogies provide the strongest support for common ancestryi. Homologous bones in vertebrate forelimbs but with different functionsi. Genetic homologyi. Genetic code is nearly universal1. Ex: codon in a dog codes for the same amino acid in a dog and in ahumanXIV. Evolutionary change can create new speciesa. Change in form can occur fairly quickly given strong pressure to changeb. Ex: larger tomatoes, sweeter apples, altering animal breeding all via artificial selectionc. Artificial selection shows the same kind of mechanism of natural selection but in a quicker time periodd. The different forms of the birds reflect their selection pressuresi. Ex: long beaks to suck out nectar from inside flowers, thicker beak to break