Chapter 16.1 Introduction to Evolution and Evidence Vocabulary Evolution Artificial Selection Natural Selection Homologous Structures Vestigial Structures Adaptation Variation Key Concepts Who was Darwin and what was his theory on evolution? How structural and physiological structures relate to evolution?
How many scientists are involved in developing the theory of evolution? William Bateson George Buffon Watson and Crick Hugo de Vries Theodosius Dobzhanky Eldredge and Gould J.B.S. Haldane Hardy and Weinberg James Hutton Thomas Huxley Jean Baptiste Lamarck Carolus Linneaus Charles Lyell Thomas Robert Malthus Ernst Mayr Gregor Mendel John Ray George Simpson G. Ledyard Stebbins Alfred Russel Wallace` Alfred Wagner
What kinds of sciences did these scientists study? Biology Paleontology Geology Genetics Botany Naturalists Microbiology Biochemistry Molecular chemistry Ecology Chemistry
When did the theory of evolution begin to develop? Late 1600 s with John Ray Major contribution was his writings called Historia Plantarum Rejected the system of dichotomous division where species were classified by a preconceived type of system Instead, plants were classified by similarities and differences from observation Coined the term species
When did Darwin write Origin of the Species? 1859 So about 200 years after Ray
Look at the drawings carefully then answer the following questions 1) What is the main difference you notice about the Galápagos finches? 2) Why do you think this difference exists?
Natural Selection and the Evidence for Evolution (16.1)
DEFINITION OF EVOLUTION: change over time: the process by which modern organisms have descended from ancient organisms.
The Life of Charles Darwin Portrait of Darwin in 1840 (31 years old) (Darwin 65 years old)
The Life of Charles Darwin Born 1809 (England) Completed college after studying to become a doctor but could not stand sight of blood Set sail on 5 year voyage on H.M.S., Beagle in 1831 as the natural historian for expedition.
The Life of Charles Darwin Made extensive drawings and notes on the trip but also collected many species of plants and animals. Began to OBSERVE that animals were well adapted to their environments, (wondered why were different animals found in areas that appeared to be similar in climate? and some survived while others did not?) Argentina Australia Europe All had grasslands but very different animals
The Life of Charles Darwin He collected fossils. noticed some looked like living organisms others looked like nothing he had ever seen before Were these related to the living (present day) organisms? Why did some organisms disappear altogether?
Where are the Galapagos?
The Life of Charles Darwin Galapagos Islands Organisms Darwin Observed on the Galapagos Land Tortoise = different shaped carapace (shell) depending what island they inhabited. Finches = different shaped beaks depending on environment in which they lived. he realized that characteristics of many animals and plants varied noticeably among the different islands of the Galapagos. On the journey home he began to pose the question Could animals on the different islands once have been members of the same species?
Those Who Influenced Darwin Hutton (Geologist) Geologic processes operate extremely slowly (take millions of years!) therefore, the earth is very old
Lyell (Geologist) Scientists must explain past events in terms of processes that they can actually observe processes that shaped the Earth millions of years ago continue to shape present day Earth this explained how geological features can be built or torn down over long periods of time.
Darwin wondered If the earth could change over time, could life change as well? Also: it must have taken many, many years for life to change the way Darwin had in mind This would only be possible if the earth was very old
Those Who Influenced Darwin Malthus (Economist) proposed that war, famine, disease, limits the growth of human populations if populations continue to grow unchecked, they will run out of resources (food/shelter)
2 IMPORTANT CONCEPTS TO HELP US UNDERSTAND THE PROCESS OF EVOLUTION: Variation & Adaptation
VARIATION: differences between individuals in a population
Give me an example, PLEASE!! ADAPTATION: inherited characteristic that increases an organism's chances of survival
EXAMPLES OF ADAPTATIONS!
What are some adaptations this polar bear has? How do they help polar bear s survive?
How are the adaptations of this bear different than those of the polar bear?
What are some adaptations of a cactus?
What about this desert plant?
What helps this kelp crab survive? (It lives on the kelp in the ocean.)
What the heck are these?
EVIDENCE FOR EVOLUTION 1) Fossils: evidence of once-living things (shells, casts, bones, teeth, imprints) show a succession of forms through a vast span of time progressive changes based on the order they were buried in sedimentary rock few fossils / species simple organisms many fossils/ species complex organisms
EVIDENCE FOR EVOLUTION 2) Biogeography and age of the earth: distribution of plants & animals 13 species of finches on the 13 Galapagos Islands 57 species of kangaroos all in Australia!
2) Biogeography and age of the earth: Radioactive dating tells us the earth is about 4.6 billion years old Rate of motion of tectonic plates
3) Adaptations: Evidence for Evolution MIMICRY: one species resembles another CAMOUFLAGE: enables species to blend with their surroundings PHYSIOLOGICAL: ability to resist disease or drought
4) Artificial Selection 4) Applied Genetics ("artificial selection"): Darwin noticed that farmers selected the best crops, animals he wondered if there could be a selective force in nature today we see DDT-resistant insects; antibiotic-resistant bacteria
5) Anatomical Structures: Evidence for Evolution
Homologous Structures = shared common anatomical or biochemical traits ex: " forearm bones structures that develop from the same clumps of cells later develop into structures that have different forms and functions arms, flippers, & wings look very similar at the beginning of development, but differ as the animal matures The function differs as well!
Vestigial Structures: structures that no longer serve a purpose in an organism ex: wisdom teeth, tailbone, appendix, nictitating membrane, some pythons & boa constrictors have tiny leftover leg bones (and whales!) koala's have a large functioning appendix (eat primarily plant materials)
6) Embryological Development Similarities of vertebrate organisms in early stages of development All animal development begins in the same way (from the same ball of cells) BUT recognizable features for that species develop as the organism grows
7) Cellular and Molecular Evidence: Cellular Evidence All organisms are made of cells consist of membranes filled with water containing genetic material, proteins, lipids, carbohydrates, salts and other substances
7) Cellular and Molecular Evidence Molecular Evidence the DNA code links all life on Earth to a common ancestor DNA and RNA = simple four-base code that provides the recipe for all living things Transfer genetic material from the cell of one living thing to the cell of another the recipient would follow the new instructions as if they were its own EX: Roundworms share 25% of their genes with humans.
Protein Sequence Similarities!
Review major evidence for evolution Fossil record Biogeography and age of the earth (using radioactive dating) Adaptations Artificial Selection Homologous structures and vestigial organs Embryology Cellular and Molecular Evidence