Evolution Lecture for Bio 105

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BIOL - Biology
BIOL 105
Gregory Zagursky

Biology 105- Evolution Mutations can change the meanings of genes They are changes in the DNA base sequence These are caused by errors in DNA replication or by mutagens Chemicals, viruses, UV radiation The change of a single DNA nucleotide causes sickle-cell disease Mutations and evolution 1 in a million- rare effects 1)neutral- no benefit, no harm 2)harmful- altered or lost protein function, usually kills the cells and or organism quickly 3)beneficial- helps the organism survive and reproduce better than the rest of the population The history of Evolutionary Thought The divine order of nature- in place until the 1700’s a) each species was created individually and never changes b) earth was the center of the universe c) man stood atop creation d) in the early 1700’s the earth was thought to be 4000-6000years old Lamarck (1809)- suggested the first theory of evolution Inheritance of acquired characteristics Organisms themselves brought about physical changes during their lifetimes, that could be passed onto their offspring Darwin’s theory of evolution A sea voyage helped Darwin frame his theory of evolution 1809-1882 Charles Darwin while on the voyage of he HMS beagle in the 1830’s Charles Darwin observed similarities between living and fossil organisms the diversity of life on the Galapagos Islands, such as blue-footed boobies, giant tortoises, marine iguanas and Darwin’s finches Darwin became convinced that the earth was millions of years old and constantly changing 1) he concluded that living things also change, or evolve over generations noticed that armadillos in an area strongly resembled fossil armadillos found in the same area 2) he also stated that living species descended from earlier life forms; descent with modification Darwin’s finches- each had developed a distinct beak shape to exploit local food Darwin proposed natural selection as the mechanism of evolution Darwin observed that organisms Produce more offspring than the environment can support varying among characteristics that can be inherited Biology 105- Evolution Darwin reasoned that natural selection Results in favored traits being represented more and more and unflavored ones less and less in ensuring generations of organisms Darwin found convincing evidence for his ideas in the results of artificial selection The selective breeding of domesticated plants and animals Darwin proposed that living species are descended from earlier life forms and that natural selection is the mechanism of evolution The study of fossils provides strong evidence for evolution Fossils and the fossil record strongly support the theory of evolution Transitional forms are evidence of evolutionary change 1) hominid skull 2) petrified trees 3) ammonite casts 4) scorpion in amber 5) “ice man” the fossil record shows that organisms have appeared in a historical sequence many fossils link every extinct species with species living today these fossilized hind leg bones link living whales with their land-dwelling ancestors A mass of evidence validates the theory of evolution Biogeography The geographic distribution of species suggested to Darwin that organisms evolve from common ancestors Darwin noted that Galapagos animals resembled species of the south American mainland more than animals on similar but distant islands Comparative anatomy 1) homologous structures- similar structures in two or more species that arose from the same structure in a common ancestor the structures don’t necessarily perform the same function 2) vestigial structures/ comparative embryology- all vertebrate embryos look similar to one another in early development, with the development of a tail and
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