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Change Over Time Are living things related to other living things? Why do living things change? How do living things change? In your own words, describe what YOU think the theory of evolution means… Charles Darwin Darwin’s Theory of Evolution Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world. Voyage of Beagle Dates: February 12th, 1831 Captain: Charles Darwin Ship: H.M.S. Beagle Destination: Voyage around the world. Findings: evidence to propose a revolutionary hypothesis about how life changes over time Patterns of Diversity Darwin visited Argentina and Australia which had similar grassland ecosystems. those grasslands were inhabited by very different animals. neither Argentina nor Australia was home to the sorts of animals that lived in European grasslands. What shaped Darwin’s theory? Darwin studied the many different species he saw on his voyage. He was curious and wanted to explain why some species greatly resembled others found elsewhere. He thought that they must have had a common ancestor. What shaped Darwin’s theory? He noticed that most plants and animals that inhabit a specific area are well suited to their environment, but yet there are different species all over the world even in similar habitats. Example: Argentina, Australia, and England have similar grassland ecosystems, yet the animals living in the areas were different. What shaped Darwin’s theory? • Darwin collected and analyzed fossils. Some of the fossils resembled organisms that were still alive and others looked completely unlike any creature he had ever seen. What shaped Darwin’s theory? The Galapagos Islands Darwin observed that the characteristics of many animals and plants varied noticeably among the different Galapagos Islands. What shaped Darwin’s theory? The finches on each island were different Beak type seemed to match the food available on each island What shaped Darwin’s theory? Selective Breeding Experiments or Artificial Selection Artificial selection is where plants or animals with a desired trait are specifically bred with the hopes of increasing the chances that the trait will appear in the offspring. Examples include dog breeding and cultivating hybrid plants. Patterns of Diversity Darwin posed challenging questions. Why were there no rabbits in Australia, despite the presence of habitats that seemed perfect for them? Why were there no kangaroos in England? Living Organisms and Fossils Darwin collected the preserved remains of ancient organisms, called fossils. Some of those fossils resembled organisms that were still alive today. Living Organisms and Fossils Others looked completely unlike any creature he had ever seen. As Darwin studied fossils, new questions arose. Why had so many of these species disappeared? How were they related to living species? The Galapagos Islands The smallest, lowest islands were hot, dry, and nearly barren-Hood Island-sparse vegetation The higher islands had greater rainfall and a different assortment of plants and animals-Isabela- Island had rich vegetation. The Galapagos Island Darwin was fascinated in particular by the land tortoises and marine iguanas in the Galápagos. Giant tortoises varied in predictable ways from one island to another. The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited. If the only available food is located high on a bush, which turtle is better adapted to eat? Galapagos Island tortoises • The tortoises’ shell shape and neck corresponded to different habitats. The Isabela Island tortoise has a dome-shaped shell and a shorter neck. The vegetation is more abundant and closer to the ground here. The Hood Island tortoise has a long neck and a shell that is curved and open around the neck and legs, allowing the tortoise to reach the sparse vegetation on Hood Island. There are finches on the mainland and on all the islands The finches are very similar except for their beaks The beaks differ from island to island The beaks are always a match to the food source. Darwin reasoned the finches began as a single species in Equator As competition for space & food increases, some finches fly to one of the islands. The food source on that island is slightly different, finches lucky enough to have the ‘right’ beak for the new food – eat, grow, develop, reproduce & pass on that “beak” trait. Over time, more & more of the finches have the ‘new’ beak A new species of finch begins. Repeat to other islands What did Darwin find out? How did Darwin interpret his observations? Observation Inference Very similar birds All finches Lots of variation Lots of competition Environment can only support a limited number of birds By chance, some birds inherit beaks that enable them to eat different foods Eat – survive -- reproduce – Pass on “good” trait Group 1 Group 2 Original beak New beak The birds share common ancestry Similar birds Different beaks Different food sources More birds can share same environment because they are not eating the same food Natural Selection -Species change, morph toward better balance with environment -One species splits into 2 species Animals found in the Galapagos Land Tortoises Darwin Finches Blue-Footed Booby Marine Iguanas The Journey Home Darwin Observed that characteristics of many plants and animals vary greatly among the islands Hypothesis: Separate species may have arose from an original ancestor What shaped Darwin’s theory? Charles Lyell (geologist) Proposed the idea of uniformitarianism Proposed the idea that the age of the Earth was much older than commonly thought at that time (Like billions of years old instead of thousands) Lamarck’s Theory of Evolution • Jean-Baptiste Lamarck (Was TOTALLY WRONG!) Thought organisms could change their traits in response to environmental changes. Then these changes would be passed on to their offspring. Example: Thought that a giraffe could stretch its neck to reach higher food and then pass its long neck on to its kids. Lamarck was WRONG, but he was the first to figure out that organisms adapt to their environments. What shaped Darwin’s theory? Thomas Malthus (Economist) Said that there were too many organisms and not enough natural resources so organisms were in competition with each other. Darwin realized Lyell’s idea of an older earth allowed for the time needed for changes to occur in populations. Malthus’ idea on competition provided the force that caused changes in a population. The Science Theory of Evolution • Species* change over time and space – staying a good match to their environment • All organisms share common ancestors with other organisms. explains the similarities of organisms & the inheritance of traits The primary mechanism of change over time is natural selection. species - populations of interbreeding organisms Essential Question Why do some organisms survive and others do not? Moth Story There is naturally variation in the color in moth offspring - light to dark gray. In the original forest, moths live near tree trunks that are light in color. In this environment the light gray color moths have advantage. (matching the tree color helps them not get eaten, so they can eat and survive.) However, when a new factory is built nearby soot and smoke accumulates in the air causing the tree trunks to darken. In terms of Natural Selection - what will happen to the moth population? Let’s explain how that will happen Natural selection (12:44): http://www.youtube.com/watch?v=aTftyFboC_M&safe=active Darwin’s Theory of Natural Selection: 1. In nature, organisms produce more offspring than can survive. 2. Individuals have variations that make them different from others of their own kind. 3. Individuals in the same population compete to survive. 4. Individuals with favorable variations survive and pass their genes on to offspring. 5. Over time, offspring with certain variations make up most of a population and can look and act very different from their ancestors. What is the “good” variation(s) ? How does that “good trait” give advantage ? What is the ‘good” variation ? How does that “good trait” give advantage ? What is the ‘good” variation ? How does that “good trait” give advantage ? What is the “good” variation ? How does that “good trait” give advantage ? What is the ‘good” variation ? How does that “good trait” give advantage ? Who has the answer? Natural Selection & Artificial Selection Natural variation--differences among individuals of a species Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful. Evolution by Natural Selection The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities Survival of the Fittest-Some individuals better suited for the environment Natural Selection Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment Natural Selection Adaptation: any inherited characteristic that increases an organism’s chance of survival. Explains how evolution occurs: the gradual change in species over time Evolution occurs in species if the variation helps the organism to survive. This variation must then be passed on to offspring. Evolution applies to a whole population NOT an individual! Adaptations Structural Adaptations: 1. Mimicry: one species mimics the appearance of another. Viceroy Bee (Non-Toxic) Monarch Bumble Bee Moth (Toxic) How would looking like a dangerous species be a survival advantage? Adaptations Structural Adaptations: 2. Camouflage: species blend in with surroundings. Walking stick Leopard Ground squirrel How would blending in be a survival advantage? http://www.pbs.org/wgbh/nova/evolution/evolution-action-salamanders.html Adaptations Physiological Adaptations: Adaptations in the jobs that body parts perform Antibiotic Resistance (MRSA) http://www.popsci.com/article/science/fda-aims-reduce-use-antibioticsfattening-farm-animals http://www.popsci.com/science/article/2012-02/how-antibiotics-yourmeat-are-making-superbugs-stronger Pesticide Resistance http://www.nytimes.com/2010/05/04/business/energyenvironment/04weed.html?pagewanted=all&_r=0 2 ways the present day chicken is better adapted to today’s environment than its ancestor would have been 1. smaller size – needs less food for survival, 2. has feathers rather than fur – lighter and water resistant – can fly? Descent Descent with Modification-Each living organism has descended, with changes from other species over time Common Descent- were derived from common ancestors Evidence of Evolution The Fossil Record Geographic Distribution of Living Things Homologous Body Structures Similarities in Early Development Evidence for Evolution The Fossil RecordLayer show change Geographic Distribution of Living Things Homologous Body Structures Similarities in Early Development Evidence of Evolution The Fossil Record Geographic Distribution of Living Things-similar environments have similar types of organisms Homologous Body Structures Similarities in Early Development Homologous Structures Homologous Structures-structures that have different mature forms in different organisms, but develop from the same embryonic tissue Comparative Anatomy In what specific ways are these ‘forearms’ alike? Comparative Anatomy How does anatomy support the Theory of Evolution? Common prototypes o backbone, legs, eyes •Internal organs – heart, digestive, nervous Same structure modified for different purposes Well adapted animals have advantage in their environment Let’s activate our thinking with this brainstorm: Limbs help an animal move - but there are lots of variations. Record 3 different types of limbs & how they help animals move Evidence for Evolution Vestigial organs- any structure that is so reduced in function or size that they are just vestiges or traces of the original structure. The structure may have been used in an ancestor, and may still be used in another animal alive today. i.e.) appendix, miniature legs Example #1: Appendix in humans Example #3: Pelvic bone in whales Example #2: Small leg bones in pythons Evidence for Changes Over Time SIMILARITIES IN EMBRYOS: similar embryos suggest that similar genes are at work in early development. Groups of embryonic cells develop in the same order and in similar patterns. The same set of genes control this development. Suggest a common ancestor. Show strong evolutionary relationships Evidence for Changes Over Time DNA/amino acid comparisons: The more similar the DNA the more closely related organisms are. What’s an embryo? Embryology = the study of embryos How does embryology support the Theory of Evolution? Similar developmental pattern Supports common ancestry Evidence of Evolution Embryology How does embryology support the Theory of Evolution? Evidence of Evolution Embryology How does embryology support the Theory of Evolution? Similar developmental pattern Evidence of Evolution Embryology How does embryology support the Theory of Evolution? Similar developmental pattern Supports common ancestry Embryos and DNA (3:43) : http://www.dnatube.com/video/420 7/What-Can-Embryos-Tell-UsAbout-Evolution 4 Key Points that support the Theory of Evolution #1 • in any population, lots of offspring are born • many die • There is a struggle to survive 4 Key Points that support the Theory of Evolution #2 •There are variations within a population • Some variations make it easier to survive 4 Key Points that support the Theory of Evolution #3 • Well adapted adults survive (eat & don’t get eaten) • grow & develop • reproduce • pass on traits • resulting in well adapted offspring 4 Key Points that support the Theory of Evolution #4 •As the environment changes, different variation in traits help an organism survive. • Individuals with these variations survive Adaptation & Evolution is always about the ones who survive!! Summary of Darwin’s Theory Individuals in nature differ from one another Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce. Summary of Darwin’s Theory Because more organisms are produced than can survive, each species must struggle for resources Each organism is unique, each has advantages and disadvantages in the struggle for existence Summary (cont.) Individuals best suited for the environment survive and reproduce most successful Species change over time Summary (cont.) Species alive today descended with modification from species that lived in the past All organisms on earth are united into a single family tree of life by common descent Meerkat Adaptations (45sec): http://video.nationalgeographic.com/video/education-videos/education-general/edu-meerkatadaptations/ Zebra Stripes: http://animal.discovery.com/tv-shows/other/videos/fooled-by-nature-zebras-stripes.htm Extinction Adaptations allow organisms to survive in their environment. However, organisms that are too well-adapted (or specialized) to their environment have trouble adjusting if the environment changes suddenly. Extinctions occur when species disappear from earth forever. Mass extinctions occur when a lot of different species become extinct in a short period of time. Extinction rate is the speed at which species are disappearing. Mass Extinction The first mass extinction, the Permian extinction, occurred 248 mya and wiped out 90% of the species on earth. Possibly caused by an Ice Age and/or a massive volcano. The second major mass extinction, the Cretaceous-Tertiary extinction, occurred 65 mya and wiped out 50% of species including dinosaurs. Human-Caused Extinctions Human activities are rapidly changing natural habitats. Extinction rate is skyrocketing right now. This is known as the “biodiversity crisis” Biodiversity refers to the wide variety of different types of organisms that live on Earth. Biodiversity is important for a healthy ecosystem. It is easier for bio-diverse ecosystems to recover from natural disasters and other sudden changes. Different species are all connected in the ecosystem so the extinction of one might lead to the extinction of lots more. Why Is Biodiversity Important? Who Cares? Endangered Species In order to protect biodiversity many governments and non-profit organizations are committed to protecting endangered species. An endangered species is one whose numbers are so low that it is in danger of going extinct.