Transcript Evolution
Evolution The Earth has been home to living things for about 3.8 billion years. Evidence Fossils – the remains of once living organisms preserved in the Earth Types of fossils: Hard Body parts (such as bones, teeth, shells) Imprints in Sedimentary Rock Which rock layer is the oldest? Mass Extinction A period when large number of species became extinct at nearly the same time. Permian Era- 225 mya: 90% of marine life when extinct Cretaceous of dinosaurs Era – 65 mya. Disappearance How did new species arise on Earth? Evolution- the change of a species over a LONG period of time. We know today that the changes arise from genetic mutations or variations that are passed down from generation to generation. But where did this idea come from? 2 Theories of Evolution 1. Theory of Acquired Characteristics The idea that a species can “get” a trait by passing it on to the next generation. Lamarck! Lamarck thought that if an animal acquired a characteristic during its lifetime, it could pass it onto its offspring. • Charles Darwin Naturalists who published The Origin of Species after studying a variety of species on his voyage. 2. Theory of Natural Selection Natural Selection – the best trait that is suited for the environment will allow a species to survive and reproduce at a higher rate The Beagle Darwin’s Voyage 1831-1836 The Galapagos Island (just read…) 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. The Galapagos Islands Darwin collected the preserved remains of ancient organisms, called fossils. Some of those fossils resembled organisms that were still alive today. 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 Discovery of Genetics?!?!? Mendel and his peas • From 1856-63, a monk called Gregor Mendel cultivated 29,000 pea plants to investigate how evolution worked i.e., how characteristics were passed down the generations. • He figured out the basic principles of genetics. He showed that offspring received characteristics from both parents, but only the dominant characteristic trait was expressed. Mendel’s work only came to light in 1900, long after his death Four Factors that support Natural Selection Adaptation- trait Overproduction – an abundance of offspring are produced, but not all survive. Variation- results from mutations and increases the variety of traits in a species that allows species to survive and reproduce in a particular environment. Selection – organisms with particular adaptations are most likely to survive and reproduce. 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 Where food was limited, competition meant that only the fittest would survive. • • This would lead to the natural selection of the best adapted individuals and eventually the evolution of a new species. Welcome to Shark Tank! Bacho Size Sacho 15 feet 20 Macho Watcho 25 feet 8 feet feet # of pups 20 10 30 5 10 9 15 0 20 yrs 10 yrs 15 yrs fathered # of pups that lived to adulthood Age Which shark is the fittest? 15 yrs Natural Selection Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment Evidence of Evolution Fossilized Evidence Similarities in Early Embryonic Development Geographic Distribution of Living Things Homologous Body Structures Fossilized Evidence Similarities in Early Development (look @ colorsheet) Evidence for Evolution Vestigial organs - physical structures that were fully developed and functional in an ancestral group of organisms, but is reduced and unused in the later species. So basically… organs that serve no useful function in an organism i.e.) appendix, miniature legs, arms Homologous Structures Similar structures that are related species have inherited from a common ancestor. Ex- the bones in a bird’s wing, dolphin’s flipper, dog’s leg, human’s arm GENETIC EVIDENCE!!! Works Cited http://www.pbs.org/wgbh/evolution/change/fami ly/index.html http://www.ucmp.berkeley.edu/education/explor ations/tours/Trex/index.html What did T-Rex taste like? http://www.thebrights.net/images/TeacherRequest%20Form.pdf http://www.nclark.net/Evolution#Activities Activity Natural Selection in the Peppered Moth