Chapter 11: Evolution: Evidence and Theory Essential Question: Why is there a large variety of living things? How did the differences come about? I. History of Evolutionary Thought A. The Idea of Evolution 1. Evolution a) Development of new types of organisms from preexisting types of organisms over time (difference between ancestor and relative: science does not propose that humans evolved from chimpanzees: humans and chimpanzees share a common ancestor) b) Heritable change in the characteristics within a population from one generation to the next Evolution Born 1809 to a wealthy family his father was a physician and wanted him to be a doctor or a minister. Enrolled at the University of Edinburgh at the age of 16, but was repelled by surgery with no anesthesia very experimental at the time. He skipped lectures to collect biological specimens instead. His father sent him to the University of Cambridge to study theology in 1827, but had little interest in the course of study. Discovered his love of natural history. While at Cambridge he became close friends with John Henslow (botanist). Fun Facts about Darwin: (do not need to write down) 2. Charles Darwin: naturalists that took a trip around the world in the 1830s and observed diverse and unique organisms a) Galapagos Islands: noticed that groups of animals varied from island to island (finches and tortoises) b) Noticed similarities and differences among animals around the world c) Darwin took years to put together his evidence for a theory of evolution and his theory forms the basis for modern thoughts on evolution 5-year mapping and collecting expedition to South America and the South Pacific Darwins role as the naturalist: collect specimens (including fossils), observe thousands of species, record observations take notes and make sketches Dropped off at different ports along the journey and would be picked up months later (seasick) The Voyage of the Beagle Pinta Island Intermediate shell Pinta Isabela Island Dome-shaped shell Hood Island Saddle-backed shell Hood Floreana Santa Fe Santa Cruz James Marchena Fernandina Isabela Tower Giant Tortoises of the Galpagos Islands Section 15-1 Galapagoss Tortoise Galapagos's tortoise can live for over 150 years Eat plants Different shells depending on the island Galapagos's Tortoise 3. Ideas of Darwins time a) Most scientist thought that all species were permanent and unchanging b) Thought that the Earth was only thousands years old and not billions c) Scientists began to present evidence that the species on Earth have changed over time and that the Earth was much older 4. Ideas about geology a) Strata: rock layers; were being studied and strata are formed as new layers of rock are deposited over time b) Lower strata were formed first and are the oldest c) Different layers of strata hold fossils of different kinds of organisms d) Showed that organisms in the past differed greatly from any living species e) Some species become extinct: species ceased to live after a point in time f) Geologic processes that have changed the shape of Earths surface in the past continue to work in the same ways (uniformitarianism) g) Darwin used the idea that if the Earth could change, organisms could also change 5. Lamarcks ideas on Evolution: supported the idea that populations of organisms change over time a) Acquired trait: organisms could acquire traits during their lifetimes as a result of experience or behavior and then pass on those traits to offspring b) Acquired traits was not correct Lamarck Lamarcks Theory of Evolution Section 15-2 B. Darwins ideas 1. Darwins travels around the world help him form a theory to explain evolution and he published a book called On the Origin of Species by means of Natural Selection 2. Descent with Modification: used to describe the process of evolution a) Every species must have descended by reproduction from preexisting species b) Species must be able to change over time c) All species have descended from only one or a few original kinds of life 3. Galapagos island finches: 13 different species of finches that came from just a few original species of finches a) Each island had a different type of food source b) The beaks of the finches of each island adapted to the certain kind of food Darwin C. Natural selection: process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals natural selectionnatural selection Four main parts of Darwins reasoning for natural selection 1. Overproduction: more offspring can be produced than can survive to maturity a) Environment limits the population of all organisms by causing deaths or by limiting births 2. Genetic variation: within a population, individuals have different traits and the traits can be inherited 3. Struggle to survive: individuals must compete to find food, shelter, etc. a) Some variations improve an individuals chance to survive and reproduce, but some variations reduce the chance b) Adaptation: trait that makes an individual successful in its environment AdaptationAdaptation 4. Differential reproduction: organisms with the best adaptations are most likely to survive and reproduce a) The organism will pass on its traits through inheritance to its offspring and the trait will become more frequent in the population b) Theory of natural selection proposes that nature changes species by selecting traits. The environment selects the traits that may increase in a population by selecting the parents for each new generation c) Survival of the fittest d) Fitness: organisms ability to reproduce and pass on its traits FitnessFitness II. Evidence of evolution: gradual modifications are seen A. Fossil record 1. Fossil: remains or traces of an organism that died long ago a) Shows that different types of organisms appeared at different times and places on Earth b) Extinct: species is no longer alive c) Most powerful evidence of evolution Rock layers 2. Transitional species: species have features that are intermediate between those of ancestors and later descendant species B. Biogeography: study of the location of organisms around the world 1. Animals around the world seemed closely related yet were adapted to different environments 2. Mammals of Australia resemble wolves, cats and mice, but are marsupials, so they probably evolved in isolation C. Anatomy and Embryology 1. Anatomy: study of the body structure of organisms 2. Embryology: study of how organisms develop 3. Homologous structures: structures that occur in different species and that originated by heredity from a structure in the most recent common ancestor a) Related structure but function may be different b) Example: limb bones of humans, penguins, alligators and bats HomologousHomologous 4. Analogous structures: closely related functions but do not come from the same ancestor a) Example: wings on birds, bats, and moths have different structures that evolved independently Analogous 5. Vestigial structures: no function in the organisms, but they resemble structures that had a function in related organism a) Appendix and tailbone in humans Vestigial Pelvic bones in whales. in snakes. . Ex eyes on cave dwelling animals, wings on flightless birds Blind Cave Salamander D. Biological Molecules 1. Compare DNA, RNA, and proteins of organisms 2. Greater the number of similarities between any given species, the more closely the species are related through a common ancestor E. Phylogeny: relationships by ancestry among groups of organism 1. Tree is made using different evidence to show how closely organism are related 2. Trunk: represents a past species that could have been the ancestor of all these animals 3. Branches: separate population 4. More closely related groups appear closer to each other on a branch PhylogenyPhylogeny III. Evolution in Action: evolution is a continuous process and it is going on today A. Convergent evolution: process by which different species evolve similar traits even though they had different ancestor 1. Example: Sharks and dolphins have similar body shapes but one is a fish and one is a mammal B. Divergent evolution: descendants of a single ancestor become more and more different due to different environments: produced the large variety of species alive today 1. Example: Galapagoss Island finches Comparison C. Artificial selection: human breeder chooses individuals that will parent the next generation 1. Dogs and other domesticated animals 2. Plants like corn and oats D. Coevolution: two or more species have evolved adaptations to each other 1. Predators and prey 2. Parasites and hosts 3. Plant eating animals and the plant 4. Humans have developed and used antibiotics to kill bacteria, but some bacteria have evolved to resist the antibiotics coevolution Darwin Prezi