Evolution. Ocean Life & Evolution DNA. Sir Charles Lyell ( ) Lecture #13 Week #11. A.K. Morris, Ph.D. 19th Century - New Theories

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1 Ocean Life & Evolution Chapter 12 Evolution THE foundation for understanding life ecological behavioral physiological molecular Great moments in evolution Deviating a bit from the book 1 2 DNA The blue print for all life All living organisms have the same parts, just different combinations We re all related at some level Let s take a brief trip in history CHARLES DARWIN ( ) Born same day as Abraham Lincoln Sent to medical school, but dropped out Childhood fascination with nature Only way to study nature was in the clergy th Century - New Theories Scholars attempt to reconcile evidence of change w/ creationism Cuvier - multiple catastrophes Lamark - inheritance of acquired characteristics Sir Charles Lyell ( ) Remember him??? Uniformitarianism proponent (Earth formed by slow continuous processes) Promoted Geologic Time Wrote Principles of Geology (12 editions! ) Focus on process Explained fossils on mountaintops Challenged the view that Earth is 6,000 years old 5 6

2 Inside cover of Principles of Geology (way before it s time ) Captain Robert FitzRoy ( ) Brilliant young sea captain A science enthusiast Read Principles of Geology, and actually knew Lyell Assigned captain of the HMS Beagle after the previous captain shot himself Didn t want to be lonely on his next voyage, so 7 8 The Connection Approached Darwin (FitzRoy s second choice) FitzRoy gave Darwin a copy of Lyell s book he was fascinated by it. He had observed barnacles on cliff tops and now had potential explanation Armed with this new paradigm, he took a little trip with FitzRoy Voyage of the Beagle 9 10 Seasickness Darwin got VERY seasick. Spent 3 of the 5 years on land Spent much time on horseback in S. America. (avoiding the boat) Collected specimens and made careful observations

3 Darwin s Big Idea After the Beagle cruise, Darwin never set foot on a boat EVER again. Amassed a huge amount of data. Spent years analyzing it all Began formulating ground breaking ideas Malthus - Struggle to Survive Thomas Malthus ( ), well known economist contemporary of Darwin Argued that as pop size increases, resources dwindle, the struggle to live intensifies and conflict increases Influenced Darwin provided a frame of reference for his developing ideas But he was scared of the implications Species have high reproductive potential Produce WAY more offspring than can possibly survive Consider the elephant Why? Life is hard Many survive. But not all 17 18

4 The challenge: Environment: Cold, hot, windy, wet, dry, etc Food: Not enough, not right kind, not right time Glyptodonts & Armadillos In Argentina, Darwin observed fossils of extinct glyptodonts Animals resembled living armadillos Predators: One or many Competition: Too slow, too weak, too scared, too dumb Off coast of Ecuador Galapagos Islands Darwin Wolf Variation Darwin observed variation in all living species Observed unique spp. but similar to mainland Hypothesis: Descended from spp that arrived from elsewhere Fernandia Pinta Marchena Genovesa Santiago Bartolomé Seymour Rabida Pinzon Baltra Santa Cruz Isabela Santa Fe Tortuga San Cristobal Española Floreana Variation in length of adult humerus bones in an extinct bird (La Brea Tar Pits) Variability exists in all living organisms Darwin saw this Individuals with different traits Ex. Lighter vs. darker, taller vs. shorter Some traits convey an advantage Reflect/absorb sun keeps them cooler/warmer A.K. Morris 23 24

5 Darwin s Big Idea Species differ in traits that are heritable Affects ability to survive and reproduce B/c spp produce more offspring than resources, spp will compete Causes populations to change over time 25 Natural Selection Natural Selection - Differential survival and reproduction of indiv. in a pop. Over time, filtering, along w/ changing environment causes changes in genetic makeup/ traits in populations Take Home Message: Evolution is a continuous process Natural Selection is the mechanism. 26 Organisms w/ favorable traits survive better and reproduce more Traits get passed to next generation Selection (continued) Indiv. w/ unfavorable traits do not survive or reproduce. Only genes for favorable traits are passed I m da man Ladies, one at a time, please. 27 Darwin award winner 28 Think of nature like a filter. Environment: -climate -predators -habitat -disease -etc. Darwins 4 simple steps Natural Selection How it works: 1. Organisms reproduce more than can survive 2. All populations have variation 3. Some variation is heritable 4. Over time, as the environment changes, a population will end up exhibiting more favorable traits (e.g. frequency of favorable alleles increases) Future generations 29 30

6 Alfred Wallace Arrived at same conclusions as Darwin Wrote to Darwin describing his views Prompted Darwin to finally present his ideas in a formal paper Darwin waited 20 years knew it would be controversial They presented it together in 1858 (sort of Darwin didn t show up) didn t get much fanfare. But 31 Origin of Species Published in 1859 Sold out in the first day Not immediately accepted By 1930s, science had matured Population Ecology Genetics Game Theory Systematics Natural Selection provided a mechanism that connected all of these disciplines 32 Artificial Selection For thousands of years, humans have been modifying species by artificial selection But not everyone was convinced that such a thing could happen on a large time scale The smoking gun eluded Darwin Early Ideas About Heredity Everyone knew that sperm & eggs transmitted info from parents Blending inheritance??? Totally stumped Darwin Problem: Expect variation to disappear? And yet variation persists Father Gregor Mendel Czech mathematician LOVED gardening Published in 1865, and rediscovered in 1900 How much change can happen over long periods of time? His work described behavior of chromosomes (where genes reside) during cellular reproduction (aka meiosis) Never knew DNA existed 35 36

7 Adaptation Changes in morphology, physiology, or behavior that help organisms cope w/ environment Diversity Life is diverse because species adapt in different ways But they maintain some similarities because they possess the same basic traits from common ancestors Natural selection produces indiv s adapted to survive in a particular environment Evolution today Mass Extinctions The modern synthesis Marries Darwin s initial concept with genetics and population theory. Major debates in science around Evolution were basically over by the end of the 1920s. What factors force rapid evolutionary changes? 39 Fig Box 13.1, p. 368

8 Chicxulub Crater, Yucatán Mexico Evidence for Evolution More evidence exists for evolution than for the Theory of Gravity Fossil Biogeography Anatomical Biochemical and many others 43 Box 13.1, p Fossil Evidence Every fossil is one more line of evidence Simplest Complex thru geological time Archaeopteryx Anatomical Evidence Vestigial structures (advantageous at one time) Humans: tail bone, appendix, body hair, etc. Anatomical Evidence Homology versus Analogy Homologous structures Others: hind limbs in whales and snakes YOU! 47 48

9 Anatomical Evidence Analogous structures Biochemical Evidence Whether you are a crab, an amoeba, giant kelp, or a blue whale, we all follow these same rules: All these animals have evolved flat swimming structures independently This NEVER varies DNA = A-C-T-G, RNA = A-C-U-G Genetic Code is Universal 20 amino acids to build EVERYTHING Small genetic abnormalities give us glimpses of our past? How many nipples do you have? 51 "A Remarkable Case of External Hind Limbs In A Humpback Whale" By Roy Chapman Andrews. American Museum of Natural History, Novitates No TOKYO, Japan (AP) Japanese researchers said Sunday that a bottlenose dolphin captured last month has an extra set of fins that could be the remains of hind legs, a discovery that may provide further evidence that oceandwelling mammals once lived on land. November 5, 2006 So, all living populations evolve But there are other unifying things All living things are made of CELLS We all METABOLIZE We all REPRODUCE to be continued next week!