Transcript Notes 7-3
Notes 7-3 Evolution of species Habitat • Environment that provides what an organism needs to live, grow, and reproduce • Examples: Dessert habitat, coral reef habitat, grassland habitat • Non-Examples: Africa, United States, Mexico (these are too broad) Gene Pool • All the genes in a species • Variety of genes • These variations can be caused by rearrangement of genes in meiosis or genetic mutations • Variety on the gene pool helps ensure survival of the species Formation of a new species • Geographic isolation: • A new species can form when a group of individuals remains isolated from the rest of the group long enough to evolve different traits • Could be separated by a river, mountain range, ocean, etc. Kaibab and Abert’s Squirrels • These two kinds of squirrels have been isolated from one another for a long time. Eventually this isolation may result in two different species. Inferring species relationships • Scientists have always hypothesized how closely related species can be by comparing fossils, embryos, and body structures • Now, scientists can compare DNA and protein structures to use as further, more concrete evidence • Scientists used to think lesser pandas and giant pandas were closely related. This branching tree diagram shows how scientists now think that raccoons and lesser pandas are closely related, and giant pandas and bears are closely related based on DNA evidence. Species Status • A species status has to do with how many organisms there still are of the species • If the numbers of organisms is low, the species may be threatened, vulnerable, endangered, or critically endangered • If there are no members of that species still alive, it is extinct Extinction of Species Extinction is caused by a change in species' environment. The members of a species may not have adaptations that allow them to survive and reproduce in the changed environment. Examples of the changes could be disease, predators, over hunting, climate change, etc. Baiji White Dolphin • one of the most recent species to fall victim to human civilization • the aquatic mammal had fallen prey to hunters and fishermen Captivity • In an effort to try to save many species from going extinct they are sometimes placed in captivity • This could be a zoo, national park, large area of land, etc. • What are the benefits for the organisms in captivity? Endangered species project • You will be doing a research project on an endangered or extinct species (more info to come next class) • For homework, you are to come up with a species that you would like to research. • You must get it okayed by me next class • The next slide will have many species for you to choose from, or feel free to go home and pick your own • • • • • • • • • • • • • • Wooley Mammoth Polar Bear Dodo bird Baiji Dolphin Tasmanian tiger Asian elephant Gray wolf Egyption vulture American crocadile Rainbow parrotfish Speartooth shark Lotis blue butterfly Cougar Giant kangaroo rat • • • • • • • • • • • • • • Gopher frog African Lion American Bison Aru Flying fox Cheetah Clouded leopard Giant otter Grevy’s Zebra Owl-faced monkey Pink fairy armadillo Red panda Sea otter Brown bear Bighorn sheep