Chapter 5 and 6 Evolution of Living Things & History of Life on Earth

Chapter 5 and 6Evolution of Living Things &History of Life on Earth Sections 1-3 Pages 106-129 Sections 1-3 Pages 136-153

Differences among Organisms • Adaptation: A characteristic that helps an organism survive and reproduce in its environment. Adaptations may be physical behaviors. • Species: A group of organism that can mate with one another to produce fertile offspring. Groups of individuals of the same species living in the same place make up a population.

Do species change over time? • Evolution: The process in which inherited characteristics within a population change over generations such that new species sometimes arise

Evidence of Changes over Time • Fossils: remains or imprints of once living organisms • Usually formed from complete organisms, parts of organisms, or a set of foot prints • Fossil Record: organizes fossils by their estimated ages and physical similarities

Earth’s History as a Clock

Change over Time: Evidence of Ancestry • Drawing Connections Scientists examine the fossil record to figure out the relationships between extinct and living organisms

Examining Organisms • Evidence of whale evolution: using fossils to support the hypothesis

Comparing Organisms • Comparing skeletal structure: similar bones can be examined in different animals to demonstrate a common ancestor • Comparing DNA: If species that have similar traits evolved from a common ancestor , the species would have similar genetic code

How Does Evolution Happen? • Charles Darwin: During a 5 year voyage, this 21 year old, traveled post college to study nature. • On his journey aboard the Beagle, Darwin collected plant and animal samples. He visited the Galapagos Islands.

Darwin’s Finches • Noticed the similarities between plants and animals on Galapagos and Ecuador (600 miles apart).

Darwin's Thinking • Traits: a genetically determined characteristic • Selective Breeding: The human practice of breeding animals or plants that have certain desired characteristics

Ideas about Population • Darwin gained knowledge from Thomas Malthus’ book An Essay on the Principle of Population. • Darwin reasoned that the offspring of survivors inherit traits that help the offspring survive in their environment.

Ideas about Earth • Darwin began to think species could evolve over time. • Darwin learned from Principles of Geology (Charles Lyell) that Earth had been formed by natural processes over a long period of time.

Darwin’s Theory of Natural Selection • Darwin struggled for over 20 years with his ideas until Wallace mailed him a letter expressing similar ideas • In 1859 Darwin published Origin of the Species by Means of Natural Selection in which he proposed the theory of evolution happens through a process that he called natural selection

Genetics and Evolution • Darwin lacked evidence for parts of his theory • He could not prove how variation occurred • Scientists today found that variation happens as a result of differences of genes • These changes occur whenever offspring are produced • These changes allow the organism better ability to survive and reproduce, this is called selection

Changes in Population • Adaptation to Hunting: example tusk less elephants • Insecticide Resistance: insects can develop quick resistance because of their rapid reproduction of offspring, having a shorter generation time • Competition for Mates: example bird species

Forming a New Species – Speciation • Separation: usually begin when part of the population gets separated from the rest (mountain range, canyon, lake formation) • Adaptation: over generation the separated group develops new traits • Division: If the two groups are reunited (barrier removed) they are no longer the same species and can not reproduce with each other

Fossilized Organisms • A fossil is the remains or physical evidence of an organism preserved by geological processes • Fossils in rock: sometimes decaying organisms get quickly buried by sediment (rock), then the sediment becomes a rock. The harder parts of the animal (bones) become well preserved in this newly formed rock. • Fossils in amber: Organisms (insects) get caught in soft sticky tree sap which hardens and preserves them.

Absolute Dating • The process of establishing the age of an object by determining the number of years it has existed is called absolute dating.

Radiometric Dating • If you know the rate of decay for a radioactive element, you can determine the absolute age of the rock. • Based on a parent to daughter ratio, you can determine the absolute age, this process is called radiometric dating. • A half life is the time that it takes one half of the radioactive sample to decay. • After every half-life, the amount of parent material decreases by one-half. ½, ¼, 1/8, 1/16 Try this example: Carbon 14’s half-life is 5, 730 years. How old will the object containing this be when ¼, 1/8, 1/16, 1/32 of it’s Carbon 14 remains.

Geological Column • Used to help geologists, they combine data from all the known undisturbed rock sequences around the world • Geologists use the geological column to interpret rock sequences and to identify layers in puzzling rock sequences

Extinction • The death of every member of the species. • Can be caused by global change and/or change in ocean currents

Changing Earth • Pangaea: “All Earth” one supercontinent breaking up • Plate Tectonics: Continents/huge pieces of land moved slowly on plates • Adaptation to slow change: organisms from the past present along with current organisms

Precambrian Time • Time from the formation of the Earth, 4.6 billion years ago to about 543 million years ago. • Violent events (volcanic eruptions) and harsh atmosphere. • Simple chemicals may have reacted during these storms from the energy of radiation. Single celled organisms resulted (prokaryotes).

Precambrian Time • Photosynthesis and Oxygen- Cyanobacteria used sunlight to make food over 3 billion years ago, and started to release Oxygen. Ozone layer began to form as a result. • Multi cellular Organisms-A billion years after prokaryotes appeared Earth had eukaryotes (many celled organisms with a nucleus)

Paleozoic Era • Marine life flourished • Land plants appeared • Amphibians and reptiles • Insects • Largest mass extinction in Earth’s history….cause? Ocean currents?

Mesozoic Era • Age of the Reptiles • Small mammals • Dinosaurs and birds • Extinction….cause?.... Global climate?

Cenozoic Era • Age of Mammals • Mammals competed with dinosaurs • Due to climate change…mammals better suited for environment

Humans and other Primates • Primates – group of mammals that include humans, apes, monkeys, and lemurs (opposable thumbs and binocular vision) • Hominids- includes humans and other human like ancestors. The main difference is bipedalism “walking upright”

Hominids through Time • Early Hominids- similar to humans more than apes. Oldest fossils in Africa- 6 to 7 millions years old. • Australopithecines- Similar to apes, found in Africa. Had human like and ape like characteristics • Global Hominids- Slender, more human like, larger and more complex brain, walked upright and used tools. (homo habilis and homo erectus)

Recent Hominids • Neanderthals- about 400,000 years ago, extinction, reason unknown • Early and Modern Humans- homo sapiens, first to create art • Paleontologists will review their ideas about evolution of hominids

Comparison of Hominids

Brain Pops, Games, etc. • Darwin • Natural Selection • Primates • Human Evolution • http://exploringorigins.org/index.html GAMES!!! • http://science.discovery.com/interactives/literacy/darwin/darwin.html • http://www.pbs.org/wgbh/nova/evolution/evolution-action.html • http://www.mnh.si.edu/ete/ETE_Education&Outreach_Game.html

Chapter 5 and 6 Evolution of Living Things & History of Life on Earth