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Transcript
Chapter 5 The Evolution of Living Things Objectives Differences Among Organisms ● Adaptation is a characteristic that helps an organism survive and reproduce in its environment Adaptations Video Differences Among Organisms ● Species are living things that share the same characteristics and adaptations. They can mate with one another to produce fertile offspring. Do species change over time? ● Scientists estimate Earth as 4.6 billion years old ● Fossil evidence shows that many species have died out and been replaced by newer species ● Evolution is the process by which populations accumulate inherited changes over time Evidence of Evolution ● Fossils ○ formed when a dead organism is covered in sediment and then minerals replace the organism with stone, or a mold is created when a hole is left behind ○ older fossils are found in deeper layers of the Earth Fossil Record Fossil Record ● Fossils found in upper (newer) layers of Earth resemble modern day organisms Gap in the Fossil Record ● Not every dead organism leaves a fossil ● Fossils are rare and often difficult to find ● Gaps remain in the fossil record Vestigial Structures ● vestigial structures-remains of once useful structures inside of a body Case Study: Evolution of Whale Hypothesis: ● Whales evolved from a land mammal based on fossil evidence Dispute: Dispute of the theory of whale evolution from land mammals Comparing Skeletal Structures ● The bones in the front limbs of multiple animals are similar ● They have evolved different functions over time Comparing DNA ● all organisms have DNA ● the more similar an organism is the more similar their DNA is Comparing Embryonic Structures ● all vertebrate embryos are similar in the early development stages Section 2 How Does Evolution Happen? ● Charles Darwin ○ served as a naturalist on board the HMS Beagle Darwin’s Adventure ● collected thousands of species ● visited the Galapagos Islands, near Ecuador and observed many organisms Darwin’s Finches ● Darwin noticed that the organisms were similar, but not identical to mainland organisms ● He noticed that the finches were different from each other ● Finches had adapted different ways to find food Darwin’s Observations ● he learned from farmers about selective breeding ● he realized that big changes could take place in a short period ● he decided that this could happen in nature, but would take longer because it would be by chance Darwin’s Observations ● he learned from geologist Charles Lyell that the Earth was very old and these changes could take place over long periods of time ● Because of Malthus’ theory on population, Darwin decided that species that survive starvation, disease & predators were better equipped to survive Natural Selection ● A four part process of evolution: ○ 1. overproduction- species produces too many offspring ○ 2. genetic variation- unique traits increase or decrease survivability ○ 3. struggle to survive- only some individuals make it to adulthood ○ successful reproduction- well adapted individuals more likely to survive and reproduce More Evidence ● genetic inheritance- variations can be caused by mutations ● most scientists believe that the theory of evolution by natural selection explains the diversity of organisms on Earth Review Why are some animals more likely to survive to adulthood than others? 1/29/14 Objectives: ● Observe two examples of natural selection ● Outline the process of speciation Section 3 Natural Selection in Action ● Natural selection continually takes place ● populations change over time in response to their environment Insecticide Resistance ● in 50 years of insecticide use >500 insects have developed resistance ● insects produce many offspring & short generation time ● generation time is the period between generations Peppered Moth White moths eaten ● pollution trees darken Dark moths survive ● moths adapted and the population changed from mostly white moths to mostly dark moths Peppered Moth Video Formation of a New Species ● Speciation- if a portion of a species is separated from the original population, they can become so different that they can no longer interbreed Speciation 1. Population becomes separated & isolated 2. Separated group adapts to new environment and evolves 3. Separated group and original group can no longer interbreed 4. The two groups are now two different species