* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Darwin and Natural Selection PPT Lecture
Sexual selection wikipedia , lookup
Objections to evolution wikipedia , lookup
Sociocultural evolution wikipedia , lookup
Natural selection wikipedia , lookup
Unilineal evolution wikipedia , lookup
On the Origin of Species wikipedia , lookup
Evidence of common descent wikipedia , lookup
Hindu views on evolution wikipedia , lookup
Evolutionary history of life wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Transitional fossil wikipedia , lookup
Creation and evolution in public education wikipedia , lookup
Acceptance of evolution by religious groups wikipedia , lookup
The Descent of Man, and Selection in Relation to Sex wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Genetics and the Origin of Species wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Chapter 22 Descent with Modification: A Darwinian View of Life (PART 1) Ms. Gaynor AP Biology Darwin made two major points in his book called Origins of Species: 1. Many current species are descendants of ancestral species 2. Natural selection is a mechanism for this evolutionary process Resistance to the Idea of Evolution • The Origin of Species = Darwin’s book –Shook the deepest roots of Western culture –Challenged a worldview that had been prevalent for centuries • Earth ONLY ~6000 yrs old • It was unchanging!!!! Nature and Classification of Species • Greek philosopher Aristotle – organisms were perfectly formed and adapted to the world (fixed and unchanging) • Old Testament – Species individually designed by God and perfect • Carolus Linnaeus – Saw adaptations as evidence that a Creator had designed each species for a specific purpose – founder of taxonomy (biology concerned with classifying organisms) & binomial nomenclature (scientifically naming organisms- Genus species) Fossils, Cuvier, and Catastrophism • The study of fossils helped to lay the groundwork for Darwin’s ideas • Fossils • remains or traces of organisms from the past, usually found in sedimentary rock, which appears in the layers or strata • Paleontology • study of fossils • developed by French scientist Georges Cuvier • Cuvier advocated catastrophism • species disappear due to a catastrophic event of earth’s crust (volcano, earthquake…) Hutton’s Theory of Geological Change • Changes in Earth’s crust due to slow continuous processes • Idea Known as Gradualism Charles Lyell Proposed theory of Uniformitarianism Geological processes at uniform rates building & wearing down Earth’s crust Proposed that the Earth was millions of years instead of a few thousand years old Lamarck’s Theory of Evolution (1809) • Lamarck hypothesized species evolve through • use and disuse and • inheritance of acquired traits • The mechanisms he proposed are unsupported by evidence Lamarck’s Theory of Evolution • Idea called Law of Use and Disuse • If a body part were used, it got stronger • If body part NOT used, it deteriorated s • Will his kids be born with big muscles because he has them? WILL THE OFFSPRING BE NICELY PRUNED? Principles of Populations • Thomas Malthus (1798) – Studied moths and natural selection • Capacity to over-reproduce is seen in all species • Eventually populations stop increasing in size and reach a steady state (carrying capacity) Charles Darwin • LOVED nature • Sails on HMS Beagle at 22 and voyaged around world • Noted flora and fauna on islands off of South America • Contributions of Lyell, Hutton and Malthus lead him to his mechanism for evolution • species change through natural selection • http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html The Voyage of the Beagle • Collected specimens of South American plants and animals • Observed adaptations of plants and animals that inhabited many diverse environments • Main focus of geographic distribution of species = Galápagos Islands near the equator west of South America The Galapagos Islands • Small group of islands 1000 km west of South America • Very different climates • Animals on islands unique England EUROPE NORTH AMERICA PACIFIC OCEAN ATLANTIC OCEAN AFRICA Galápagos Islands HMS Beagle in port Equator SOUTH AMERICA Darwin in 1840, after his return AUSTRALIA Cape of Good Hope Cape Horn Tierra del Fuego Darwin returned 5 years later in 1836 Tasmania New Zealand Darwin’s Focus on Adaptation • Adaptation= a change in structure or habits, often hereditary, to improve survival and reproduction in environment – Adaptation to environment and the origin of new species are closely related processes • EXAMPLE –Finches on the islands resembled a mainland finch –Finches had different types of beaks adapted to their type of food gathering LE 22-6 Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. Seed eater. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. Insect eater. The green warbler finch (Certhidea olivacea) used its narrow, pointed beak to grasp insects. Darwin’s Overall Observations • Left unchecked, the # of organisms of each species will increase • In nature, populations tend to remain stable in size • Environmental resources are limited More of Darwin’s Observations • Individuals of a population vary in characteristics with no 2 individuals being exactly alike. • Much of this variation between individuals is inheritable. Darwin’s Overall Conclusions • Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals • Only a fraction of offspring survive each generation • Survival of the Fittest Darwin’s Conclusion • Individuals who inherit characteristics (adaptations) that are most fit (suitable/favorable) for their environment are likely to leave more offspring than less fit individuals •Called FITNESS •High survival = more offspring = more fit Darwin’s Conclusion • Natural Selection –gradual, nonrandom process by which traits become more/less common in a population –Acts on PHENOTYPES (adaptations), which influences GENOTYPES –only organisms best adapted to environment tend to survive and transmit genetic traits to future generations while those less adapted tend to be eliminated –Key mechanism to evolution http://www.pbs.org/wgbh/evolution/educators/teac hstuds/svideos.html •Video #4: How Does Evolution Really Work? • 1844 • Darwin wrote an essay on natural selection but did not publish it • 1858 • Alfred Russell Wallace developed a similar theory of natural selection to Darwin’s (organisms evolve from common ancestors) • Darwin quickly finished The Origin of Species and published it the next year Darwin’s Descent with Modification • descent with modification • refers to idea that all organisms are related through descent from common ancestor that lived in the remote past • the history of life is like a tree Darwin’s st 1 Idea: Evolution • What is evolution? – All accumulated changes across successive generations in inherited characteristics of populations – A change over time in the genetic combination in a population give rise to diversity • Darwins definition = Descent with modification Darwin’s 2nd Idea: Natural Selection •If an environment changes over time, natural selection may result in adaptation to these new conditions new species can also evolve Natural Selection vs. Artificial Selection • Recall Natural selection – http://bcs.whfreeman.com/thelifewire/content/chp23/2 302001.html • In artificial selection, • humans modify other species over many generations by selecting and breeding individuals with desired traits What is a “hypothesis” is science? • An educated prediction based on observation • IT MUST BE TESTABLE!! • Usually supported or rejected through experimentation or more observation –A hypothesis can be disproven but it can NOTbe proven true. What is a “theory” is science? • Scientific definition of theory is different from everyday meaning – non-scientific context of “theory” implies that something is unproven or speculative • Scientific definition refers to a comprehensive explanation of some aspect of nature that is supported by a vast (A LOT) body of evidence (data). What is a “theory” is science? • summarizes a hypothesis(es) that have been supported with repeated testing • If enough evidence accumulates to support a hypothesis, it moves to the next step—known as a theory—in the scientific method and becomes accepted as a valid explanation of a phenomenon • a theory is an explanation or model based on observation – theories can be proven or rejected, just like hypotheses. What is the difference between the scientific method and a “theory” is science? • In the scientific method, there is a clear distinction between facts, which can be observed and/or measured • In a theory, scientists create explanations and interpretations of the facts which have been observed and/or measured REPEATEDLY using the scientific method – A good theory is that it formed from a number of hypotheses that can be tested independently. What is a “law” is science? • A theory is an explanation of an observations • A law is a description of observations – no exceptions have been found to a law – laws explain things, but they do not describe them. • One way to tell a law and a theory apart is to ask if the description gives you a means to explain 'why'. – Many laws are mathematical equations. – EXAMPLE: • Kepler's Laws of Planetary Motion, for example, describe the motions of planets but do not provide an explanation for their movements. What is a “belief”? • Definition –trust, faith or confidence in someone or something • faith almost always implies certitude even where there is no evidence or proof Often not based on REPEATED collected data! Is Evolution JUST a THEORY??? Is it SCIENCE based? • http://www.pbs.org/wgbh/evolution/educa tors/teachstuds/svideos.html • Video #1: Isn’t Evolution Just a Theory? 1. Homology • a similarities in characteristic traits resulting from common ancestry 2. Anatomical Homologies • anatomical resemblances that represent variations on a structural theme present in a common ancestor • Called HOMOLOGOUS STRUCTURES • Same development, different function LE 22-14 Human Cat Whale Bat 3. Vestigial organs • remains of structures once important in organism’s ancestors –Example: tailbones in humans, appendix, wings on ostrich, wisdom teeth in humans 4. Comparative Embryology 5. Molecular Homologies • Similar genes (DNA), RNA or amino acid sequences –Example • genes shared among organisms inherited from a common ancestor • Ex #1: Homeobox is a DNA sequence in genes that regular development in plants, animals and fungi • http://www.pbs.org/wgbh/evolution/library/03/4/l_034_04. html LE 22-16 Species % of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide Human 100% 95% Rhesus monkey 87% Mouse 69% Chicken 54% Frog Lamprey 14% Ex #2: Amino Acid/ Protein sequence 6. Biogeography • the geographic distribution of species Sugar Glider Marsupial •Some similar mammals that have adapted to similar environments have evolved independently from different ancestors Flying Squirrel Eutherian (placental) 7. Genetic Changes over time • Bacteria becomes resistant to antibiotics 7. Fossil Records • Paleontologists have discovered fossils of many transitional forms • Shows variety on organism across time Key Concepts What is the raw material necessary for the mechanism of Natural Selection? • Heritable variations What is the smallest unit of evolution? • Populations (NOT individuals) • Darwin incorporated Lyell’s gradualism into biological evolution combined with Malthus’ observations regarding populations Some Cool Evolution Videos… • Poison Newts – http://www.pbs.org/wgbh/evolution/library/01/3/l_013_07.ht ml • Camouflage “Leaves” – http://www.pbs.org/wgbh/evolution/library/01/1/l_011_03.ht ml • Evolution of the Eye – http://www.pbs.org/wgbh/evolution/library/01/1/l_011_01.ht ml • Why Does Evolution Matter Now? (Video #6) – http://www.pbs.org/wgbh/evolution/educators/teachstuds/svi deos.html