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Jean-Baptiste Lamarck – “Inheritance of Acquired Characteristics” • Thought that organisms could change during their lifetime and pass those changes onto their offspring. . •. His theory does not work, but it involved the environment • Ex. The long neck in a giraffe Charles Darwin (Father of Modern Evolution) 1. Darwin on the HMS Beagle • 1831, the 22-year-old Darwin gets a job as a naturalist on a British ship to tour the world for 5 years. • His job is to study, collect, observe, and record nature. 2. Galapagos Islands • Found off the west coast of South America • Darwin’s most interesting finds are here. 13 different species of finches (birds), all with different beaks. •Tortoises with very long necks. • How Natural Selection works: a) All organisms produce more offspring than survive. b) All organisms exhibit variation. c) Environment selects those individuals best suited for survival. d) Variations favored by selection are inherited and passed on to the next generation. e) Over long periods of time, successful variations produce differences that result in new organisms. Natural Selection “Survival of the Fittest” Adaptations • Mimicry – Structural adaptations that allow one species to look like another. • Camouflage – Adaptation that allows species to blend in with it’s surroundings. Walking stick camouflage Anatomy Homologous Structures – Structure features with a common evolutionary origin. • Ex. Forelimbs of a whale, croc, and bird. Many similarities. •Analogous Structures – No evolutionary origin, but share the same function. •Bird wing and insect wing • For example, insect and bird wings probably evolved separately when their different ancestors adapted independently to similar ways of life. • Another type of body feature that suggests an evolutionary relationship is a vestigial structure—a body structure in a present-day organism that no longer serves its original purpose, but was probably useful to an ancestor. Vestigial Organs – Functionless parts of an organism. Eyes in a cave dwelling salamander. What in humans? • Many organisms have vestigial structures. • Vestigial structures, such as pelvic bones in the baleen whale, are evidence of evolution because they show structural change over time. • Recall that an adaptation is any variation that aids an organism’s chances of survival in its environment. Physiological adaptations can develop rapidly Non-resistant bacterium Antibiotic Resistant bacterium The bacteria in a population vary in their ability to resist antibiotics. When the population is exposed to an antibiotic, only the resistant bacteria survive. The resistant bacteria live and produce more resistant bacteria. Breeding organisms with specific traits in order to produce offspring with identical traits is called _______. A. B. C. D. natural selection adaptation mutation artificial selection What is the difference between artificial selection and natural selection? How does mimicry differ from camouflage? • In nature, physical barriers can break large populations into smaller ones. • Geographic isolation occurs whenever a physical barrier divides a population. • A new species can evolve when a population has been geographically isolated. • When geographic isolation divides a population of tree frogs, the individuals no longer mate across populations. • The formation of a river may divide the frogs into two populations. The Evolution of Species • Over time, the divided populations may become two species that may no longer interbreed, even if reunited. Diversity in new environments • When an ancestral species evolves into an array of species to fit a number of diverse habitats, the result is called adaptive radiation. Loxodonta africana Elephas maximus 0 1 2 Elephas 3 4 Mammuthus primigenius Loxodonta Mammuthus 5 Primelephas 6 Ancestral species about 55 million years ago Extinct mamo Amakihi Crested honeycreeper Kauai Niihau Possible Ancestral Lasan finch Molokai Oahu Maui Lanai Akialoa Kahoolawe Akepa Akiapolaau Akikiki Liwi Hawaii Apapane Maui parrotbill Palila Ou Grosbeak finch Why are the Galapagos Islands rich in unique species of organisms? . Geographic isolation has helped to keep the islands’ species unique. Convergent Evolution Organisms that evolve similar adaptations because they occupy similar niches or habitats yet are not related. They may look similar because they do the same thing, such as dining on ants, hunting in high grasses or swimming in the dark. Convergent Evolution Dolphins and sharks are unrelated organisms that have evolved similar traits because they share similar environmental pressures. Would these be considered analagous or homologous structures? Why do some insects and bacteria evolve adaptations more rapidly than other species? Insects and bacteria are examples of species that reproduce in large numbers and many times in a relatively short span of time, allowing adaptations to be more easily observed. \ Are the fangs of a rattlesnake and the fangs of a spider homologous structures or analogous structures, and why? \ The fangs of these organisms are analogous structures. They share the same function in each organism, to deliver venom, but the organisms do not share a common evolutionary origin. Why is the presence of pelvic bones in the baleen whale considered to be evidence of evolution? Pelvic bones are evidence that whales once possessed hind limbs. Since whales now have no hind limbs, their loss must be the result of an evolutionary change.