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Change Over Time- Course 2 11-3 Biodiversity and Extinction Essential Question: HOW DO LIFE FORMS CHANGE OVER TIME? How Do New Species Form? What Factors Affect Biodiversity? Why do Species Go Extinct? Vocabulary Biodiversity – The total number of different species on Earth, including those on land, in the water, and in the air. Extinction – The disappearance of all members of a species from Earth. Endangered Species – A species in danger of becoming extinct in the near future. Threatened Species – A species that could become endangered in the near future. My Planet Diary pg. 394 Crickets, Maggots, and Flies, Oh My! A male cricket chirps to attract a mate. Unfortunately, chirping also attracts a parasitic fly. Parasitic flies listen for chirping crickets. When a cricket is located, a female fly deposits larvae onto the cricket’s back. The larvae, or maggots, burrow into the cricket. The maggots come out seven days later, killing the cricket in the process. Parasitic flies reduced the cricket population on the Hawaiian island of Kauai between 1991 and 2001. By 2003, the cricket population on Kauai had increased. The male crickets were silent! In about 20 cricket generations, the crickets had evolved into an almost silent population. 1. Why do you think the crickets on Kauai evolved so quickly? _______________________________________________________ 2. If most of the male crickets can no longer chirp, how do you think it might affect the size of the cricket population? _______________ _______________________________________________________ How Do New Species Form? Pg. 394 Natural selection explains how variations can lead to changes in a species. But how could a new species form? A new species can form when a group of individuals remains isolated from the rest of its species long enough to evolve different traits that prevent reproduction. Isolation, or complete separation, occurs when some members of a species are cut off from the rest of the species. Example of Natural barriers: a river, volcano, or mountain range may separate group members. It is possible that one day each set of group members will become so different from each other that they will no longer be able to mate with each other and will become separate species! Biodiversity and Extinction pg. 395 The map shows the ranges of Kaibab and Albert’s squirrels. What conditions might differ from one side of the Grand Canyon to the other that would cause the squirrels to be different colors? __________________ __________________ __________________ __________________ __________________ __________ Assess Your Understanding pg. 395 I get It! Now I know that new species form when _____________ _______________________________________________________ _______________________________________________ Albert Squirrel-Grand Canyon Kaibab Squirrel –Grand Canyon What Factors Affect Biodiversity? Pg. 396 Biodiversity is the number of different species in an area. Factors that affect biodiversity in an ecosystem include: • area • climate • genetic diversity • niche diversity Area pg. 396 Park Size Within an ecosystem, a large area will usually contain more species than a small area. For example, you would usually find more species in a 100-squaremeter area than in a 10-squaremeter area. The dark green area represents three different park plans. Circle the plan supports the most bio-diversity. Climate pg. 396 Climate affects the biodiversity in a certain area. For example, tropical rain forests are the most diverse ecosystems in the world. They are warm and have large amounts of rainfall throughout the year. Many plants grow year-round, which means that food is always available for other organisms. In contrast, a tundra region has a very short growing season. Low temperatures and low rainfall limit the biodiversity in that climate. Genetic Diversity pg. 397 Diversity is very important within a species. Species need genetic diversity. Organisms in a healthy population have diverse traits such as color and size. Species that lack a diverse gene pool are less able to adapt and survive changes in the environment. Niche Diversity pg. 397 Coral Reefs are the second most diverse ecosystems in the world. Found only in shallow, warm waters, coral reefs are often called the rainforests of the sea. A coral reef supports many different niches. Niche- a role of an organism in its habitat, or how it makes its living. A coral reef enables a greater number of species to live in it more than a uniform habitat like a flat sandbar, does. Assess Your Understanding pg. 397 1a. A (smaller / larger) area will contain more species than a (smaller / larger) area. b. How is biodiversity related to niches? ___________________________________________________ ___________________________________________________ c. You have been elected as the environmental manager of your country. What could you do to protect biodiversity? ___________________________________________________ Now I get it! Now I know that the factors that affect biodiversity include ___________________________________________________ ___________________________________________________ Why Do Species Go Extinct? Pg. 399 Extinction - When all the members of a species disappear from Earth. Extinction usually occurs when a species is unable to adapt within a changing environment. Process of ExtinctionImagine a species of spider that depends on a certain plant for food. • Now suppose the plant has died out. • If this insect can not adapt and find a new food source • they will begin to die. • Once the size of their population drops to a certain level • the species may not be able to recover and may become extinct. Endangered Species pg. 398 The green sea turtle is a well-known endangered species in Florida. But did you know that Florida also has endangered insect species? The Schaus Butterfly is endangered because its forest habitat is shrinking. Why do you think some endangered species get more attention than others?___________________________________________________ _________________________________________________________ Extinction and Human Activities pg. 399 A threatened species is one that can become endangered. An endangered species is one that is in danger of becoming extinct. Extinction is a natural process that usually happens gradually. However, most scientists think that extinction rates have increased in recent years due to human activities. Slow Down for Panthers! Road signs such as this one warn drivers in Florida to watch out for panthers in the road. Do the Math! Pg. 399 Florida Panthers This pie chart shows the causes of death for Florida panthers between 1997 and 2007. 1. Interpret Data- What is the leading cause of death for Florida panthers? _______________________________ 2. Predict- To reduce the amount of panthers hit by cars, scientists have installed tunnels uner major roadways. The tunnels allow panthers to cross roads unharmed. What is another way that you could reduce the number of panther deaths each year? _______________________________ _______________________________ _______________________________ Assess Your Understanding pg. 399 I get it! Now I know that a species may go extinct because: _______________________________________________________ _______________________________________________________ List of Extinct Animals in the Last 100 Years Arabian Ostrich Bubal Hartebeest Caribbean Monk Seal Colombian Grebe Guam Flying Fox Laysan Rail Javan Tiger Little Swan Island Hutia Passenger Pigeon Round Island Burrowing Boa Schomburgk's Deer Thicktail Chub Atitlan Grebe Bushwren Carolina Parakeet Crescent Nail-tail Wallaby Hawai'i 'O‘o Kaua'i 'O‘o Palestinian Painted Frog Pyrenean Ibex Ryukyu Wood-pigeon South Island Piopio Toolache Wallaby Bali Tiger Canarian Black Oystercatcher Caspian Tiger Golden Toad Heath Hen Laughing Owl Paradise Parrot Roque Chico de Salmor Giant Lizard Santo Stefano Lizard Tasmanian Wolf Western Black Rhinoceros