Transcript Speciation
Islands Introduction Islands are unique because they are similar Quick Question #1 What do you think this statement means? Refer back to what you know from rat island I. Islands Unit Overview The Story: • This unit is about both biological and geological evolution. • Islands provide interesting, unusual examples of evolutionary change on a scale that is small and easy to understand. • While the results of island evolution tend to be very different from evolution on a continental landmass, the mechanisms are the same. Islands simply become the context to learn evolutionary mechanisms. Quick Question #2 Give your best definition of an island II. What is an Island? A. Definition: Islands are isolated environments with unique living organisms (biology) and unique physical characteristics (geology) III. Why Do We Study Islands? A. Islands are unique because they are similar B. Islands are dynamic and often experience change, both biologically and geologically, more rapidly than continental landmasses C. Islands are smaller than continents, therefore easier to study. D. Islands allow us to study two major themes in science: Evolution (Biological Science) and Plate Tectonics (Earth Science). IV. What Happens to Organisms on Islands Over Time? A. Migrate, Survive, Reproduce, Adapt, Evolve or Go Extinct Quick Question #3 Predict at least two ways an Island can form V. How Do Islands Form? a. Rising Sea Level b. Emerging Coral Reefs (Hot Spots) c. Volcanism V. How Do Islands Form? a. Rising Sea Level • As the sea level rises due to changes in climate…land masses that were once connected are now isolated from one another V. How Do Islands Form? b. Emerging Coral Reefs • Coral Polyps and other marine animals build a house of limestone around themselves for protection • If the sea level drops or if the land underneath rises (hot spots), then “coral reefs” become exposed on the surface • Sand and dust accumulate on the reef to form an island V. How Do Islands Form? c. Volcanism • Underwater volcanoes erupt • As hot lava is emitted from the volcano, it cools and hardens to form large land masses on the water’s surface (islands) Quick Question #4 Compare and Contrast the three ways islands can be formed. VI. What Does Origin of the Island Affect? •Soil type and composition •Mineral resources •Available groundwater •Ultimately…all life on and around the island You do not need to take notes on the next 4 slides/subjects: VII. Effects on species are unique on islands VII. Effects on species are unique on islands A. Species on islands are unique. Quick Question #5 Predict why all these species grew so large in size on their islands Elephant Bird - Madagascar Giant burrowing cockroach - Australia Giant Galapagos Tortoise - Galapagos Moa VII. Effects on species are unique on islands A. Species on islands are unique. Kiwi Bird - New Zealand Quick Question #6 Predict why these bird species lost their ability to fly VII. Effects on species are unique on islands A. Species on islands are unique. Quick Question #7 Predict why all these species evolved their traits on their islands Pygmy hippopotamus – Madagascar (nocturnal) Rattleless rattlesnake - Santa Catalina Island Tree climbing kangaroo - New Guinea VII. Effects on species are unique on islands A. Species on islands are unique. Tasmanian devil - Tasmania Komodo dragon Komodo Island VIII. Causes of Uniqueness Are Similar on Islands The mechanisms that cause islands to be unique: 1. Dispersal Ability – how good a species are at migrating to new locations 2. Size Change - organisms are larger or smaller than normal 3. Loss of Dispersal Ability - species easily lose ability to emigrate 4. Endemism - species tend to evolve and remain native to that area only VIII. Causes of Uniqueness Are Similar on Islands (CONT) The mechanisms that cause islands to be unique: 5. Relictualism - populations are small and have a greater chance of extinction 6. Loss of Defensive Adaptations - defense capabilities are reduced in predator-free environments 7. Archipelago Speciation - many species may evolve from one in the same island group 8. Adaptive Radiation - many species may evolve from one in the same location because they use different parts of the habitat IX. What mode of evolution is repeatedly shown through the study of Islands? Speciation! • First: What Makes a species? – A group of individuals that can interbreed in nature. • Definition of Speciation: The evolutionary formation of new biological species, usually by the division of a single species into two or more genetically distinct ones. x. Speciation Can occur through • Geographic Isolation • Temporal (season/time) Isolation • Behavioral isolation XI. Speciation Speciation: Bottom Line • Animals and plants adapt to their new environment • Speciation occurs when organisms undergo Reproductive Isolation (where they can no longer interbreed). XII. Two main things happen that drive evolution: A. Natural Selection - “Best Fit” Survive • Ex. Camouflage, size, speed, adaptations, sex appeal, strength, intelligence, predictable human impact etc. B. Genetic Drift - “Lucky” Survive A. Ex. Extreme weather, isolation, epidemic diseases, genetic mutations, unequal gender balance, geologic activity etc.