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Chapter 14 – Principles of Evolution. What is evolution? Where did the concept of evolution come from? How does evolution occur? Why is the concept of evolution controversial to some people? What does science know about the origin of life on Earth?
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Chapter 14 – Principles of Evolution • What is evolution? • Where did the concept of evolution come from? • How does evolution occur? • Why is the concept of evolution controversial to some people? • What does science know about the origin of life on Earth? • What does science know about the origin of humans? • What evidence exists of major evolutionary transitions? Chapter 14
What is evolution? • A theory that explains the origin of life on Earth • A theory that explains why genetics of a population changes over time • A theory that explains how all life on Earth came about by changes from an original simple life form • All of these • None of these Chapter 14
What is evolution? • Evolution – (a concept, a process, and a scientific fact) A change in the frequency of alleles in a population over time • The process by which characteristics of a population changes over time (p. 265) Chapter 14
Are there changes in allele frequencies in populations over time? • Biological control of rabbits in Australia with Myxomatosis • 1952 – 99% mortality • Today – 40% mortality Chapter 14
Science explains patterns in natural systems • What can explain why Myxomatosis mortality rates have decreased in the past 50 years? Evolution – a process by which the genetic characteristics of a population changes over time Chapter 14
Did you know… • …the term “evolution” is conflated with other concepts? • The origin of the universe • The origin of the 1st life form • Common descent of species Chapter 14
Evolution vs. Evolutionary theory • Evolutionary theories • Proposed mechanisms explaining why evolution occurs Chapter 14
Where did the concept of evolution come from? • Early 1600’s – 3 fossil explanations • Inorganic • Noah’s flood • Evidence of a long history of life Chapter 14
Did you know… • …in 1508, Leonardo Da Vinci rejected a global flood as an explanation of fossil deposition? Chapter 14
Where did the concept of evolution come from? • William Smith (1769-1839) – Somerset Canal, index fossils & geological strata • 1815 – Fossil sorting inconsistent with flood scenario Chapter 14
Patterns of life Chapter 14
Locations where the entire geological column has been found intact Chapter 14
Ediacaran/Vendian life (700-550 MYA) Chapter 14
Vendian life Chapter 14
Cambrian life (500MYA) – Burgess Shale Chapter 14
Burgess Shale (British Columbia) Chapter 14
Burgess Shale fossils • Aysheaia Chapter 14
Burgess Shale fossils • Anomalocaris Chapter 14
Burgess Shale fossils • Hallucogenia Chapter 14
Burgess shale fossils • Ophabinia Chapter 14
Burgess Shale fossils • Wiwaxia Chapter 14
Did you know… • …life forms in the Pre-cambrian/ Cambrian age represent all known body plans (and all life was aquatic)? Chapter 14
Did you know… • …the continents move? Chapter 14
Seismologic patterns support plate tectonics Chapter 14
Did you know… • …the distribution of fossils supports Pangaea Chapter 14
Coprolite research Did you know… • …what dinosaurs ate? Chapter 14
Did you know… …There are no fossilized flowering plants in older sedimentary rock? • x Chapter 14
Where did the concept of evolution come from? • 1766 – Carolus Linnaeus – “Species are the work of time” • 1778 - Georges LeClerc proposed evolution, but no mechanism (theory) On modern species… “Conceived by Nature and produced by Time” Chapter 14
Catastrophism vs. uniformitarianism • Georges Cuvier (1769-1832) • – Catastrophism • J. Hutton (1785) & C. Lyell (1830) – Uniformitarianism Chapter 14
Glacial lake varves Ice core project Did you know… • …there are several independent methods that show the earth is very old? Chapter 14
Where did the concept of evolution come from? • Jean Baptiste Lamarck, 1801 – Evolution by inheritance of acquired characteristics Chapter 14
Where did the concept of evolution come from? • Charles Darwin &Alfred Wallace, 1858 – Evolution by the mechanism of natural selection Chapter 14
Charles Darwin & natural selection Chapter 14
Evolution occurs when… • A characteristic in a species is genetic • Genetic variation exists for the gene(s) involved in the characteristic • Selective pressure exists which confers a survival advantage to some individuals Chapter 14
Science, Sept. 3, 2004 • Beak differences are genetic Chapter 14
Evolution means… • The gene pool of a population (frequency of alleles) changes over time as a consequence of selective pressures • As the gene pool changes, so does the frequency of the characteristics influenced by the alleles selected for/against Chapter 14
How does evolution occur? Figure 14-5 Chapter 14
Some genetic variation confers a survival advantage in a competitive environment Chapter 14
Mutation is the source of genetic variation required for evolution Chapter 14
Alleles conferring a survival advantage will be maintained in a population Sickle cell allelefrequency Chapter 14
Sickle cell anemia • Those with 2 sickle cell alleles have a 1/5 chance of surviving to reproductive age • Those with 1 sickle cell allele have a 25% better chance of survival in a malaria environment Chapter 14
Did you know… • …that change within an individual is not evolution? Chapter 14
Natural selection and adaptation • 3 of 300 species of cichlid fishes in Lake Malawi (Africa) Chapter 14
Asteracea – 23,000 species Chapter 14
Naturally occurring pepper species Chapter 14
Artificial selection and diversity Selection of genetic variation demonstrates the great range of differences that can occur Chapter 14
Did you know… • …YECs call evolution “variation within kind”, and consider evolution to involve only large changes between different types of organisms? Chapter 14