Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Evidence for Evolution (Is there a Pattern of Change?) Scientific Method Make Observation Formulate hypothesis to explain observation Pass Test Hypothesis Hypothesis Pass Fail Theory Test Theory Fail Pass Many Theory Law Fail Can we recognize changes in populations over time? 1. Smaller scale changes in populations Biston betularia - peppered moth Peppered moth comes in two genetic types (or morphs) 1. 2. Dark Light Each morph has an advantage over the other depending on the kind of background on which they are found. They are harder to find by predators if they are on a compatible background. Industrial Pollution in England Smoke from factories darkened tree trunks And made the dark morph more difficult to see But the level of industrial smoke has been declining 300 Level of smoke (g/m3 0 1960 1970 1980 As has the frequency of the dark morph 300 100 Percent of the dark morph in the population Level of smoke (g/m3 0 0 1960 1970 1980 1. Smaller scale changes in populations - House sparrows (Passer domesticus) 1. Smaller scale changes in populations - House sparrows (Passer domesticus) Vancouver (1900) Death Valley (1914) 1852 Mexico City (1933) Costa Rica (1974) 1. Smaller scale changes in populations - House sparrows (Passer domesticus) 83 Edmonton 81 Lawrence, Kansas Death Valley Wing Length (mm) 79 77 75 Death Valley Lawrence, Kansas Edmonton 1. Smaller scale changes in populations - Lab Experiments Drosophila - Fruit fly Researchers allow two species of fruit flies to coexist in the lab. Drosophila simulans Drosophila melanogaster These flies are competing for food Hypothesis: Poorer competitors will be those that produced fewer offspring and the average number of offspring/female should increase over time. D. melanogaster D. simulans Number of offspring/female 0 At start of experiment Hypothesis: Poorer competitors will be those that produced fewer offspring and the average number of offspring/female should increase over time. D. melanogaster D. simulans Number of offspring/female 0 At start of experiment 26 generations later 1. Smaller scale changes in populations - Ring Species Herring Gull Herring Gull 1. Smaller scale changes in populations - Ring Species Vega Gull Herring Gull Herring Gull 1. Smaller scale changes in populations - Ring Species Vega Gull Birula Gull Herring Gull Herring Gull 1. Smaller scale changes in populations - Ring Species Vega Gull Birula Gull Herring Gull Herring Gull Heuglin’s Gull 1. Smaller scale changes in populations - Ring Species Vega Gull Birula Gull Herring Gull Herring Gull Heuglin’s Gull Lesser Black Back Gull Ring Species - Ensatina Original species 2. Larger Scale Evolution - Homologies Homology - similarity in characteristics resulting from shared ancestry. 2. Larger Scale Evolution - Homologies Why 5 digits on all tetrapod limbs? As opposed to analogous structures which resemble each other because of similar function. Shark Human Whale e.g. fins Octopus e.g. eyes 2. Larger Scale Evolution - Homologies DNA RNA This code is universal in all life Protein (chains of amino acids) Each amino acid has a triplet chemical code U - uracil G - guanine A - adenine C - cytosine 2. Larger Scale Evolution - Homologies Brush rabbit E. coli RNA rabbit hemoglobin Rabbit hemoglobin Definition of Evolution Changes over time of the proportion of individuals differing genetically in one or more traits These changes can occur by: • Changes in frequency of alleles and/or phenotypes in a population • Changes in the proportion of different populations in a species • Changes in the number of species in a larger taxonomic group Definition of Evolution Evolution is the pattern of change over time.