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Transcript
EVIDENCE FOR EVOLUTION (SECTION 8.2) Darwin’s Observations • Page 329 THE VOYAGE • Collected thousands of specimens. • Collected fossils that resembled existing animals. • Volcanic Galapagos Islands had species similar to S. American mainland species. • Species differed from island to island. DARWIN’S FINCHES • Collected on Galapagos. • Beaks modified to suit food source (niche). • Descended from common mainland ancestor. • Different species found on separate islands. Adaptive Radiation of Galapagos Finches • New species branched out from older ones to fill available ecological niches Darwin’s Conclusion • All life on earth is related • Currently existing organisms are descendants of past organisms • The mechanism for evolution is natural selection. Fossils • Shows numbers of extinct animals • Shows similarities between extinct animals and animals that are alive today • The earth’s layers show a time scale of species and when they appeared on earth (and when they died out) How Fossils Form • http://www.youtube.com/watch?v=TVwPL WOo9TE Transitional Fossils (Missing Links) • Archaeopteryx – link between dinosaurs & birds – Lived 150 million years ago – Discovered 1861, just two years after Darwin published Origin of Species Whale Evolution • Video http://www.y outube.com/ watch?v=I2 C-3PjNGok Tiktaalik • Transition from water to land • http://www.y outube.com/ watch?v=o5 Z4mPQBjqA • Darwinius masillae (“Ida”) is the approximately 47-million-yearold common ancestor of anthropoid primates: that is, all monkeys and apes, including humans Ida Biogeography • Homologous structures – these are parts of the body that are similar, but have different functions The flippers of whales, and the wings of birds All forelimbs of vertebrates have the same pattern of bones Common ancestry Divergent evolution Homologous Structures Analogous Structures – Some species of different origins have similar physical structures (convergent evolution) – Example1: the wings of bats and insects – Example 2: the eyes of vertebrates, molluscs (like squid and octopus) and insects Evidence of Divergent & Convergent Evolution HOMOLOGOUS ANALOGOUS • Vestigial Organs – these are organs or parts that seem to have no function in the living organism, but once had a function in an ancestor Whales have pelvic bones that do not attach to legs Remember Lamarck’s theory of disuse? Embryological Development Embryos of different species develop in almost identical ways. Human fetus at 8 weeks Biochemistry and DNA When comparing the DNA sequence of a gene or amino acid sequence of a protein between two species, more similarities are found in species that are more closely related. Lion photo credit: ucumari Tiger photo credit: digitalART2 Comparing DNA or Amino Acid Sequences http://darwiniana.org/intro1.htm Cytochrome C oxidase (mitochondrial protein found in all eukaryotes) http://www.citruscollege.edu/lc/archive/biology/Pages/Chapter17-Rabitoy.aspx Cladogram (Phylogenetic Tree) http://evolution.berkeley.edu/evolibrary/article/0_0_0/endosymbiosis_05 Primate Evolution Direct observation of species change 1. Bacteria become resistant to antibiotics 2. Artificial Selection A. Plants and animals were “domesticated” for agriculture B. Wolves were bred over many generations to become dogs and then bred further to create a variety of breeds Another example of Artificial Selection Pests become resistant to chemicals. What Evolution is NOT The theory of evolution is an explanation of the diversity and distribution of life forms on earth. It is not an explanation of the initial origin of life. This is an active area of research called “abiogenesis,” “astrobiology,” or simply origin of life (OOL). It is obviously part of the larger scientific project to understand the universe, but is • Creationism, sometimes referred to as “creation science” or “intelligent design” is the belief that organisms were placed on this earth by a divine being (God). • It is NOT a scientific theory because it does not follow scientific principles • Scientific theories require evidence, and must be based on NATURAL PHENOMENON • Finding gaps in our knowledge about evolution is a normal part of the scientific process, the existence of these “gaps” and questions does not qualify as evidence that an alternative theory must be correct • Many religious organizations do not have a problem with evolution, and it is compatible with their faith and beliefs. • Ask your religious leaders what their thoughts are. Also see the National Centre for Science Education for a list of statements from a variety of religious groups. Here’s an excellent lecture by Kenneth Miller http://media.hhmi.org/hl/06Miller.html HOMEWORK • • • • • Read Sections 7.1, 7.2 & 8.2 Page 304 #1-9 Page 311 # 2, 7, 8, 11 Page 340 # 6, 7, 10 – 13, 15 – 17 HIV evolution video – http://www.youtube.com/watch?v=34GeUa7R zvY