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Evolution Notes

Evolution Notes. Name ________________________ Date ______________ Pd _____. Fossilized Bone. Imprint Fossil. Insect in Amber. Woolly Mammoth. The History of Life on Earth. Earth has been home to living things for about 3.8 billion years Fossils provide evidence of earlier life

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Evolution Notes

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  1. Evolution Notes Name ________________________ Date ______________ Pd _____

  2. Fossilized Bone Imprint Fossil Insect in Amber Woolly Mammoth The History of Life on Earth • Earth has been home to living things for about 3.8 billion years • Fossils provide evidence of earlier life • Fossils– the remains of organisms preserved in the Earth • Types of Fossils: • Hard body parts, such as bone • Mineralsreplace parts of organism • Prints made by organisms • Original remains of entire organism

  3. Relative Dating Absolute Dating History of Life Continued… • The age of fossils can be used to determine the history of life on Earth • Relative Dating – by comparing one fossil with another fossil, it can be determined if one fossil was formed before or after another • Absolute Dating– by measuring radioactivity, the exact age of a fossil can be determined

  4. History of Life Continued… • Once the age of fossils is determined, the fossil record can be established • Fossil Record – the information about the fossils found in a particular location • The fossil record can be used to determine when a species lived or died

  5. The History of Life Continued… • The fossil record indicates that more complex organisms developed on Earth over time • At first, all living things lived in the oceans • First came unicellular organisms (3.8 billion years ago) • These are organisms made of a single cell. • Over time, different types of unicellular organisms developed – bacteria, archaea, protists, etc. • Then came multicellular organisms (1.2 billion years ago) • These are organisms made of many cells • Then came life on land (500 million years ago) • 500 million years ago the first multicellular organisms moved from water to land • First came plants, fungi, and insects, then came amphibians and reptiles, finally came birds and mammals

  6. The History of Life Continued… • Although organisms were constantly developing, Earth’s history also includes mass extinctions • Mass Extinction – when huge numbers of species have died or become extinct in a very short time • Permian Extinction (250 million years ago) • In this extinction, 90% of the species living in the oceans became extinct • Occurred when Earth’s land masses joined together • Cretaceous Extinction (65 million years ago) • In this extinction, more than half of the species on Earth (including dinosaurs) became extinct • This was caused by a meteorite collision – the evidence of this is the Chicxulub Crater

  7. The History of Life Continued…

  8. Jean Baptiste de Lamarck Lamarck’s Giraffes Life Changes Over Time • Because of the fossil record, in the past 200 years scientists have explored the idea of evolution • Evolution – the process through which species change over time • Evolution results from a change in DNA (a mutation) • Jean Baptiste de Lamarck (early 1800s) – he was the first scientist to propose an idea of how life evolved • He proposed that an organism can acquire a trait during its lifetime and pass that trait on to its offspring • This idea could not be supported by evidenceso it was not accepted as scientific fact

  9. Charles Darwin Life Changes Over Time Continued… • Charles Darwin – A British Naturalist who spent 5 years on the H.M.S. Beagle • He observed animals, especially on the Galapagos Islands • For example, when observing finches, he saw a variety of beak shapes that were adapted to what they ate and where they lived

  10. Life Changes Over Time Continued… • Darwin proposed the idea of evolution through the process of natural selection • Natural Selection – members of a species that are best suited to their environment survive and reproduce at a higher rate than other members of the species • Natural selection occurs through the continuous cycle of genetic mutation and reproduction • Key Principles of Natural Selection: • Overproduction • Variation • Adaptation • Selection

  11. Variation Overproduction Natural Selection • Overproduction: • When a plant or animal reproduces, it usually makes more organisms than can survive • Variation: • Within a species there are natural differences in traits caused by differences in DNA • These natural differences are passed from one generation to the next • Sometimes there is a change in DNA, a mutation, that is also passed on

  12. Selection Adaptation Natural Selection Continued… • Adaptation: • Sometimes a mutation occurs that makes an organism better able to survive than others • Adaptation – any inherited trait that gives an organism an advantage in its particular environment • Selection: • Species with an adaptation are more likely to survive and reproduce • This adaptation becomes more common with each generation • The environment is selecting for this trait

  13. Speciation of Salamanders Evolution • Through the process of natural selection, new species develop from earlier species • In 1859, Darwin’s observations resulted in the publication of On the Origin of the Species, a book about evolution through natural selection • Speciation: evolution of new species from an existing species • May occur when the environment changes • Isolation is essential to speciation • Isolation: • For a species to develop into two new species, two populations must be prevented from reproducing with each other • When separate, they each develop different mutations, which, over time, result in different species

  14. Evidence for Evolution • Observationsprovide evidence for theories • In order to understand the importance of Darwin’s work, it is important to understand the term scientific theory • Scientific Theory: • A statement based on fact and observation • A theory that has been widely accepted is used to explain and predict natural phenomena • Examples of Scientific Theories: • Theory of Gravity • The Big Bang Theory • Evolution through Natural Selection • A scientific theory is NOT a guess or an opinion!!!

  15. Fossil evidence for the evolution of the horse Evidence for Evolution • Fossil evidence supports evolution • Geographic evidence about fossils shows that two species with a common ancestor can develop differently in different locations • Ancestor – an early form of an organism from which later forms descend • Scientists can determine modern plants and algae have a common ancestor in fossil algae

  16. Vestigial Organ Homologous Structures Evidence for Evolution Continued • Biological evidence supports evolution • The structure of living things: • Vestigial organs– physical structures that were fully developed and functional in an earlier group of organisms but are reduced and unused in later species • Example – hip and femur bones in whales • Homologous Structures– similar structures with different functions: • Many different species share similar structures, but they are used differently by each species • This indicates a common ancestor • Example – arms and wings

  17. Similarities in Development genetic Evidence for Evolution Continued… • Biological Evidence Continued… • Development of living things: • Similarities in development – scientists have seen that many organisms are very similar during early stages of development, when an embryo • Genetic evidence supports evolution • Scientists can tell how closely related organisms are by comparing their DNA • Example – clock gene

  18. Cladograms • Cladogram – a visual representation of the evolutionary relationship among species based on the evidence collected • Show how closely (or distantly) related two species are • Show which species evolved before or after other species • Show the similarities between more closely related species

  19. Evolution of Humans • Early humanlikespecies: • Ardipithecus – one of the oldest hominid fossils found • Australopithecus afarensis – Lucy – 3.5 million years old, 1 meter tall • Fossils are 500,000 to 6 million years old • Each species is more humanlike than the one before • Over time, some hominids went extinct and others evolved. Eventually, the only one left was us, Homo sapiens.

  20. CroMagnon Skull Evolution of Humans Continued… • Neanderthals and CroMagnons lived at the same timeas modern humans, but went extinct • Neanderthals – Homo neanderthalensis • Lived 130,000 to 35,000 years ago • Larger skulls with sloping foreheads, but shorter than modern humans • CroMagnons- Homo sapiens sapiens • Lived 35,000 to 10,000 years ago • Tall with large and round skulls • Skilled hunters and toolmakers • Modern humans: • Modern humans are Homo sapiens (“wise human”) • First fossil evidence of modern humans is about 100,000 years old

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