Transcript 11-2--3x
Chapter 11 Lesson 1 Early Mid late Chapter 11: Darwin’s Theory Click! 11.2 Essential Questions: •What was Darwin’s hypothesis and how did his observations help him develop it? •What is natural selection & how does it lead to evolution? Diversity • Darwin noticed the living things on his voyage, were different than those in England • There are currently more than 1.6 million different species or organisms on Earth Fossils • Preserved remains or traces of an organism that lived in the past • Darwin was puzzled by some fossils he saw: – Bones that resemble a sloth but were much too large… Galapagos Organisms • Similarities (& differences) between Galapagos Island and South American organisms – Example: island and mainland iguanas • Concluded species change & can produce a new species over time Adaptation • A trait that increases an organisms ability to survive and reproduce – Finches different between islands • Beak shape suited to food they eat Click! Galápagos Finches The structure of each bird’s beak is an adaptation to the type of food the bird eats. Match each finch to the type of food you think it eats. Charles Darwin • Species change over many generations and become better adapted to new conditions Scientific Theory • A well supported and widely accepted explanation of nature. Artificial Selection • When only organisms with a desired trait are bred – Example, getting T-cup Chihuahuas to be tiny Trait • A specific characteristic that an organism can pass to its offspring Natural Selection • The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species. • Factors that affect NS: Overproduction, Variation, Competition Overproduction • When a species produces so many offspring that there is not enough resources for them. Variation • Any difference between individuals of the same species. • Many members of a species differ from one another. Competition Not always a physical fight Ex: Turtles not finding enough to eat • Food, space and other resources are limited, therefore members of a species must compete with one another Factors That Affect Natural Selection What are the factors of natural selection that affect a group of sea turtles over time? Variation; Each turtle has slightly different traits. Some may be protected by harder shells Overproduction; Turtles may lay eggs. Not all of the young will survive Competition; Turtles compete with one another. A faster turtle may escape from a shark Natural Selection Darwin proposed that over a long time, natural selection can lead to change • Helpful variations may accumulate in a species, while unfavorable ones may disappear Relate Cause and Effect Identify the factors that cause natural selection. Variation Competition Environmental Change • A change that can affect an organisms ability to survive and lead to natural selection. In ten years what will the monkey plants be doing? – Ex: Monkey Flowers Many monkey flowers can now grow in the soil Genes and Natural Selection • Without variations all the members of a species would have the same traits and the same chance of surviving and reproducing. • Variations can result from changes in genes and the shuffling of different forms of genes when egg and sperm join 11.3 Biodiversity and Extinction How do new species form? • A new species can form when group of individuals remains isolated from the rest of its species long enough to evolve different traits that prevent reproduction 11.3 Biodiversity and Extinction •How do species form? •What factors affect biodiversity? •Why do species go extinct? The map shows the ranges of Kaibab and Abert’s squirrels. The colors of the rocks soil and vegetation Biodiversity • The number of different species in an area – Factors that affect ______ in an ecosystem include area, climate, genetic diversity and diversity of niches Larger areas of land have more species Climates with warm temperatures and lots of rain are more diverse than cold, dry climates Click! Genetic diversity helps species survive changes in the environment Coral reefs may have many niches, allowing many species to live on them Extinction • Usually occurs when a species is unable to adapt within a changing environment Endangered species • Species in danger of becoming extinct in the near future Threatened species • Species that could become endangered in the near future Extinction and human activities Slow Down for Panthers! Road signs such as this one warn drivers in Florida to watch out for panthers in the road. Scientist estimate there are fewer than 100 panthers survive today. This occurred because of the reduction of the panthers habitat due to human populations increasing. End Extinction? • Click!