Chapter 15 Darwin and Evolution Lecture Notes PDF

Biodiversity (BIODIY1) Chiropractic and Complementary Medicine © Department of Human Anatomy and Physiology Chapter 15 – 28 : P de Lange-Jacobs  Biology Sylvia S. Mader Michael Windelspecht Chapter 15 Darwin and Evolution 2  O...

Biodiversity (BIODIY1) Chiropractic and Complementary Medicine © Department of Human Anatomy and Physiology Chapter 15 – 28 : P de Lange-Jacobs  Biology Sylvia S. Mader Michael Windelspecht Chapter 15 Darwin and Evolution 2  Outline 15.1 History of Evolutionary Thought 15.2 Darwin’s Theory of Evolution 15.3 Evidence for Evolution 3  Outcomes 15.1 History of Evolutionary Thought 1) Identify historical figures and their viewpoints before and during the development of Darwin’s theory. 4 15.1 History of Evolutionary Thought Prior to Darwin  The view of nature was determined by deep- seated beliefs held to be intractable truths rather than experimentation and observation  Fixity of species : species remained unchanged since the time of creation  Biologists had slowly begun to accept various ideas of evolution : species arise, change and become extinct due to natural forces. 5 15.1 History of Evolutionary Thought Evolution is the unifying principle of biology  Natural forces (not supernatural forces)  Genetic change  Then natural selection  Explains the unity and diversity of life Similarities between living things reflect recent common ancestry Dissimilarities between living things reflect ancient common ancestry Species adapt to various habitat and ways of life 6  History of Evolutionary Thought Mid-Eighteenth Century Influences:  Taxonomy : the science of classifying organisms  Taxonomy: use comparative anatomy to classify organisms into groups  Extant and fossils organisms ? (read) Linnaeus (1707 – 1778) believed in the fixity of species. Each species had: » An ideal structure and function, and » A place in the scala naturae (a sequential ladder of life: simplest to most complex) – He developed the binomial system of nomenclature ( example: Homo sapiens) 7 8 9 10  History of Evolutionary Thought Mid-Eighteenth Century Influences (cont.)  Count Buffon (George-Louis Leclerc 1707 – 1788): A French naturalist Wrote a 44-volume catalog of all known plants and animals Provided evidence of descent with modification (evolution) Proposed various causes including environmental influences and the struggle for existence 11  History of Evolutionary Thought Mid-Eighteenth Century Influences (cont.):  Erasmus Darwin (1731 -1802) physician and naturalist Suggested possibility of common descent Based on changes in animals during development, animal breeding by humans and the presence of vestigial structures (?) 12  History of Evolutionary Thought Late Eighteenth Century Influences :  Cuvier (1769 – 1832) a zoologist: First to use comparative anatomy to develop a system of classifying animals Founded the science of paleontology (def) First to suggest that some species known only from the fossil record had become extinct 13  History of Evolutionary Thought Late Eighteenth Century Influences :  Cuvier (1769 – 1832) (cont.) Proposed catastrophism – Local catastrophes in the past had caused the Earth’s strata to have a new mix of fossils – After each catastrophe (mass extinction), the region was repopulated by species from surrounding areas – The result of the catastrophes was change appearing over time 14  History of Evolutionary Thought Late Eighteenth Century Influences (cont.):  Jean Baptiste de Lamarck (1744 – 1829): First biologist to: 1) Propose a testable hypothesis that explained evolution and 2) Link diversity with environmental adaptation. Concluded that more complex organisms are descended from less complex organisms Proposed the inheritance of acquired characteristics – Lamarckianism 15 Lamarck’s Inheritance of Acquired Characteristics Early giraffes probably had short necks that they stretched to reach food. Their offspring had longer necks that they stretched to reach food. Eventually, the continued stretching 16 of the neck resulted in today’s giraffe.  History of Evolutionary Thought Late Eighteenth Century Influences (cont.):  Charles Lyell (1797 – 1875): Charles Lyell’s ‘Principle of Geology’ stated that:(James Hutton) # Earth is subject to slow but continuous cycles of rock formation and erosion and not shaped by sudden catastrophes. # Formation of sedimentary rock which contain fossils. # Proposed uniformitarianism, which states that rates and processes of change are constant. 17  History of Evolutionary Thought Late Eighteenth Century Influences (cont.):  Thomas Malthus (1766 – 1834): Proposed that the size of the human populations is limited only by the quantity of resources, such as water, food and shelter, to support it. Darwin: animals tend to produce more offspring that can survive. Competition for limited resources determines survival. Darwin used Malthus’s principle to formulate his idea of natural selection. 18  Outcomes 15.2 Darwin’s Theory of Evolution 1) Describe Darwin’s Theory of Evolution 2) Describe Darwin’s trip aboard the HMS Beagle and some of the observations he made. 3) Explain the concepts of Natural Selection and Adaptation 19  15.2 Darwin’s Theory of Evolution Charles Darwin (1809 – 1882) Darwin started to study medicines – then divinity - but attended many lectures in biology and geology before serving on the HMS Beagle as an unpaid naturalist. (22 years old!!) http://www.youtube.com/watch?v=XKnqj3YFXU8 20 21  Darwin’s Theory of Evolution Introduction: Read Although not his original intent, Darwin started gathering evidence during the voyage that organisms are related through descent with modification from a common ancestor and that adaptation to various environments results in diversity. 22  Darwin’s Theory of Evolution Observations of Change over time (Geology and Fossils) Remember :Darwin read Charles Lyell’s ‘Principle of Geology’ on the trip. Geological observations consistent with those of Hutton & Lyell Examples of fossils ? (Road cuttings vs Raised beaches) Accepted that earth must be very old : enough time for descent with modification to occur 23 24  Darwin’s Theory of Evolution Biographical Observation Biogeography:  The study of the geographic distribution of life forms in different places throughout the world.  Darwin saw similar-looking species in similar habitats on different continents  Examples 25  Darwin’s Theory of Evolution Biogeography is the study of the range and geographic distribution of life-forms on Earth. Darwin compared South American animals to those with which he was familiar.  Instead of rabbits, he found the Patagonian cavy (hare) in the grasslands of South America. The Patagonian cavy has long legs and ears but the face of a guinea pig. Did the Patagonian hare resemble a rabbit because the two types of animals were adapted to the same type of environment? Both animals ate grass, hid in bushes, and moved rapidly using long hind legs. Did the Patagonian hare have the face of a guinea pig because of common descent with guinea pigs? 26 The European Hare and the Patagonian Cavy Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lepus europaeus Dolichotis patagonum (European hare): © WILDLIFE/Peter Arnold, Inc.; (Patagonian hare): © Juan & Carmecita Munoz/Photo Researchers, Inc. 27  Darwin’s Theory of Evolution Biographical Observation Biogeography:  Darwin also saw how similar species replaced one another  Reasoned that related species could be modified according to the environment  Living forms could be descended from extinct forms known only from the fossil record  Examples? 28  A Glyptodont and a Giant Sloth Glyptodon – giant armadillo like animal – only studied from fossils - weighed 2000 kg a. Glyptodon Mylodon – extinct giant sloth – believed to be 6m tall b. Mylodon 29  Darwin’s Theory of Evolution Galapagos Islands : Read  Tortoises Darwin observed that tortoise neck length varied from island to island Proposed that speciation on islands correlated with a difference in vegetation  Finches Darwin observed many different species of finches on various islands Significant variety in beaks Speculated that they could have descended from a type of mainland finches Common ancestor :Geographical Barriers: Adaptation: Origin of new species 30  Galápagos Tortoises Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b. a: © Kevin Schafer/Corbis; b: © Michael Dick/Animals Animals/Earth Scenes 31  Darwin’s Theory of Evolution Natural Selection and Adaptation:  Alfred Russel Wallace and Darwin :1858, presented to the Linnaean Society of London. Natural Selection based on: Variation Compete for available resources Differ in terms of reproductive success Adapted to conditions 32  Darwin’s Theory of Evolution Natural Selection and Adaptation:  Members of a population have inheritable variations Not imperfections of fixed species Variations necessary for process of natural selection to operate Genes : unit of heredity Random mutations are the source of new genetic variations Can be harmful, helpful or neutral to survival and reproduction 33 Variation in a Population Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Lisette Le Bon/SuperStock 34  Darwin’s Theory of Evolution Natural Selection and Adaptation:  Organisms compete for Resources Malthus More individuals are produced in each generation than environment can support Read: elephants ! 35  Darwin’s Theory of Evolution Natural Selection and Adaptation:  Organisms differ in Reproductive Success Some individuals have adaptive characteristics –Favorable traits that result in increased survival and reproduction Fitness : is the relative reproductive success of an individual –The most-fit individuals in a population capture a disproportionate share of goodies –Interactions with the environment determine which individuals reproduce the most 36  Darwin’s Theory of Evolution Natural Selection and Adaptation:  Organisms become adapted Natural selection can result in a population adapted to the local environment Adaptation: Change that helps a species become more suited to its environment An increasing proportion of succeeding generations will have favorable characteristics (adaptive traits). Increase in frequency. READ 37  Darwin’s Theory of Evolution Darwin emphasized that individuals from a population vary in their:  Functional characteristics  Physical characteristics  Behavioral characteristics He proposed that these variations:  Occur randomly  Are essential to the natural selection process  Allow adaptation to the environment over time 38  Darwin’s Theory of Evolution Artificial selection  A breeder chooses which traits to perpetuate and selects the plants and animals that will reproduce All dogs are descended from the grey wolf  Began to be domesticated about 14,000 years ago.  The process of diversification led to extreme phenotypic (?) differences The wolves under domestication were separated from other wolves. Each human tribe selected for whatever traits appealed to them. 39 Artificial Selection of Animals Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Boston terrier Irish wolfhound Wolf Left: © Gary Milburn/Tom Stack & Assoc.; Top right: © Robert Dowling/Corbis; Bottom right:© Ralph Reinhold/Index Stock 40 Imagery/Photolibrary RF ;  Darwin’s Theory of Evolution Artificial selection in plants:  The following vegetables are derived from a single species, Brassica oleracea: Chinese cabbage, Brussels sprouts, and Kohlrabi.  Darwin described artificial selection as a model by which to understand natural selection. 41 Artificial Selection of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chinese cabbage Brussels sprouts Kohlrabi Wild mustard (Cabbage, Brussel sprouts, kohlrabi): Courtesy W. Atlee Burpee Company; (Mustard): © Jack Wilburn/Animals Animals/Earth Scenes; 42  Darwin’s Theory of Evolution  Darwin’s natural selection hypothesis was based on:  Observation of tortoises and finches on the Galápagos Islands. 43  Darwin’s Theory of Evolution  Each of the 13 species of Galápagos finches has a beak adapted to a particular way of life.  A heavy beak is suited to a diet of large seeds  The beak of the warbler-finch is suited to feeding on insects  A longer, somewhat decurved beak and the split tongue of the cactus-finch are suited to probing a cactus for seeds Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Large, ground-dwelling finch b. Warbler-finch c. Cactus-finch a: © Adrienne T. Gibson/Animals Animals/Earth Scenes; b: © Joe McDonald/Animals Animals/Earth Scenes; c: © Leonard Lee Rue/Animals Animals/Earth Scenes; S Eagleton 2014 44  Darwin’s Theory of Evolution  Peter and Rosemary Grant are observing natural selection as it occurs in finches on Daphne Major  The beak size of the medium ground finch adapts to the weather Read Other observations of natural selection discussion  Variation in colour patterns on the wings of the fruit flie. Industrial melanism  Bacterial resistance to antibiotics 45 45  Outcomes 15.3 Evidence for Evolution 1) Interpret one example from each area of study as evidence supporting the descent of all life from a common ancestor. 2) Interpret misconceptions of evolution proposed by Darwin’s critics Discussion 46  15.3 Evidence for Evolution Fossil evidence  Fossils are the remains and traces of past life or any other direct evidence of past life such as trails, footprints, or preserved droppings. Most: shells, bones and teeth  Fossils record the history of life from the past  Document a succession of life forms from the simple to the more complex  Sometimes the fossil record is complete enough to show descent from an ancestor 47  15.3 Evidence for Evolution Fossil evidence (cont.) Transitional fossils represent the intermediary evolutionary forms of life in transition from one type to another or a common ancestor for two different groups of organisms  They allow us to trace the descent of organisms 48  Transitional Fossils Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Amphibian tetrapod Early amphibian 360 Explain the characteristics Expanded ribs Millions of years ago (mya) Neck Flat head, eyes on top 370 Scales Tiktaalik Fins roseae 377 380 Also remember Archaeopteryx Rounded head, 49 eyes on sides Fish  Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anatomical Transitions During the Evolution of Whales a. Ambulocetus 50 mya b. Basilosaurus 40 mya modern c. Right whale 50 a: © J.G.M. Thewissen, http://darla.neoucom.edu/DEPTS/ANAT/Thewissen  Evidence for Evolution Biogeographical Evidence:  Biogeography is the study of the range and distribution of plants and animals throughout the world  Biogeographical distributions are consistent with the hypothesis that related forms of life evolved in one locale and then spread to accessible regions  Provide evidence that variability in a single, ancestral population can lead to adaptation to different environments through the forces of natural selection  A different mix of plants and animals would be expected whenever geography separates continents, islands, seas, etc. 51  Biogeography Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Sugar glider, Petaurus breviceps, is a tree-dweller and resembles the placental flying squirrel. The Australian wombat, Vombatus, Kangaroo, Macropus, is an herbivore is nocturnal and lives in burrows. It that inhabits plains and forests. It resembles the placental woodchuck. resembles the placental Patagonian cavy of South America. 52 Top left: © ANT Photo Library/Photo Researchers, Inc.; Bottom left: © Photodisc Blue/Getty RF; Right: © George Holton/Photo Researchers, Inc.  Evidence for Evolution Anatomical Evidence:  Vertebrate forelimbs: Homologous structures - All contain the same sets of organized bones in similar ways Yet they are modified extensively to meet various adaptive needs Darwin interpreted this as support for a hypothesis of common descent  Embryological development All vertebrate embryos have: A post-anal tail and Paired pharyngeal (gill) pouches 53 Significance of Homologous Structures Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. bird humerus ulna radius metacarpals phalanges bat whale cat horse human 54 Significance of Developmental Similarities Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. fish salamander tortoise chick pharyngeal pouches human postanal tail 55  The Evidence of Evolution Homologous Structures:  Anatomically similar because they are inherited from a common ancestor  May be functionally similar or not Analogous Structures:  Serve the same function  Are not constructed similarly  Do not share a common ancestor  Usually because of adaptation to the same type of environment 56  The Evidence of Evolution Vestigial Structures:  Fully-developed anatomical structures in one group of organisms  Reduced or obsolete function in similar groups  Usually because of not the same type of environment anymore 57  Evidence for Evolution Biochemical Evidence:  All living organisms: Use the same basic biochemical molecules DNA/RNA/ATP Utilize same DNA triplet code Utilize same 20 amino acids in their proteins  DNA base-sequence differences: When very similar, suggest recent common descent When more different, suggest more ancient common descent 58  Significance of Biochemical Differences Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. yeast moth fish turtle duck pig monkey human 0 Compared to Human Cytochrome c Number of Amino Acid Differences 10 20 30 Cytochrome c is a small protein 40 that plays an important role in the electron transport chain within mitochondria of all cells. 50 59  Evidence for Evolution Evidence from Developmental Biology:  All living organisms: Use the same regulatory genes  Homeobox (Hox) 60  Criticisms of Evolution  Hypothesis vs theory  Scientific evidence  Origin of life and then the diversity of life that follows.  Transitional fossils?  Mutations are random, but not natural selection  Evolution testable and observable 61