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Download 3.2 Origins of Biodiversity - Amazing World of Science with Mr. Green
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ORIGINS OF BIODIVERSITY Important Terms Important Terms Evolution: A change in the gene pool of a population over time Natural Selection: Process by which individuals that are better suited to their environment survive and reproduce more successfully. Adaptation: An inherited characteristic that increases an organism’s chance of survival. Charles Darwin Charles Darwin Charles Darwin Proposed the theory of evolution outlined in The Origin of Species Evidence of Evolution Fossil records Structure of DNA Mechanisms of mutations Natural selection as a possible driving force for speciation. Evolution is the cumulative, gradual change in the genetic characteristics of successive generations of a species or race of an organism, ultimately giving rise to species or races different from the common ancestor. Natural selection as a possible driving force for speciation. Evolution reflects changes in the genetic composition of a population over time. Natural selection as a possible driving force for speciation. Natural Selection (Evolution) comes down to a species adapting to their surroundings over time. A species with only plants to eat, will adapt to eating plants. A species with only animals to eat, will adapt to eating animals. Darwin's Research Studies 13 species of finches on Galapagos Islands Looked a beak size and shape: Stout beaks for eating seeds Short and sharp beaks for eating insects. Woodpecker-like beak for eating insects from trees, but instead of a long tongue it uses a cactus spine held in its beak to remove its prey. Natural selection as a possible driving force for speciation. Darwin’s theory of evolution by natural selection comes down to the following points: Species show variation. All species over-produce. Despite over-production, population levels remain the same. Over-production leads to competition for resources. Natural selection as a possible driving force for speciation. Darwin’s theory of evolution by natural selection comes down to the following points: The fittest, or best adapted organisms, survive. The survivors reproduce and pass on their adaptive genes to the next generation. Over time, the population’s gene pool changes and new species emerge. Natural selection as a possible driving force for speciation. What is a species… Species definition was made by humans, and fails to fully define nature. These two ants look different are the same species of ant fulfilling different roles in a colony. Pheidole barbata Species definition is not always black and white Are we the same? + ZONKEY Photo: Wiki Commons/GNU Isolation Geographical, behavioral, genetic, or reproductive factors. If gene flow between the two subpopulations is prevented, new species may evolve. Speciation occurred on the earth over a very long period of time when the continents slowly drifted apart This leads to geographic isolation Continental Drift Animation Isolation The isolated population is an isolated gene pool since it does not breed with other populations. The gene pool can therefore change as it adapts to the new conditions by natural selection. . Isolation Behavioral Isolation Changes to the appearance or behavior of the populations No longer attraction among the two types, and therefore no longer breed. Reproduction Isolation Two populations can no longer physically breed due to changes to reproductive organs. Genetic Isolation Too many genetic differences for the two populations to produce fertile young. Northern population Arctic Fox Early fox population Spreads northward and southward and separates Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage. Different environmental conditions lead to different selective pressures and evolution into two different species. Southern population Gray Fox Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Speciation Read through your packet about Speciation Plate Tectonics Plate Tectonics PLATE = a portion of the Earth’s crust TECTONICS = movement Plate Tectonics The Earth’s crust (lithosphere) is divided into many different plates. Plate Tectonics Plates are carried on the mantle (asthenosphere), which can flow like a liquid on a geological time scale. Plate Tectonics Edges of adjacent plates can either move parallel to one another, push one under the other, or collide. Theory of Plate tectonics Earth’s crust is broken into large pieces called plates Theory of Plate tectonics Plates move over time creating many landforms & geologic events such as earthquakes and volcanoes Earth Through History Because Earth’s plates are moving, the continents have not always been in their present location. Earth Through History Pangaea – large supercontinent As continents move apart – physical isolation may occur Earth Through History Geologic events – volcanoes & earthquakes can bring about loss of habitat and potential loss of species Plate Tectonics The movement of the major and minor plates in relation to one another is called plate tectonics. Plate Tectonics Movement of tectonic plates can produce barriers such as mountain ranges, oceans and rift valleys that can lead to isolation of gene pools and then speciation. Types of Plate Movements Convergent: pushed together Divergent: moving apart Transform: sliding past What happens at plate boundaries can be constructive: building new land (ie: habitats) or destructive; destroying land TRANSFORM BOUNDARIES Plates slide past with friction EARTHQUAKE ZONES No new land or habitats Divergent Physical separation of the plates Creates a rift Rifts on land result in large lakes Results in the formation of a physical barrier Convergent Physical separation Large changes due to mountains and islands Convergent Boundaries (colliding) 3 Scenarios: 2 Continents Collide = folded mountains Could lead to isolation – mountain range separates a population Creates new habitat Both constructive (building mountain) and destructive (one plate subducting) Convergent Boundaries (colliding) 2 Oceanic Plates Collide More dense plate subducts Deep sea trench Oceanic Islands New Land formation = new habitat Aleutian Island Arc: Possibility of future land bridge?? Affect on evolution & biodiversity? Plate Tectonics Land bridges can form from previously unconnected plates allowing species to spread. Plate Tectonics The movement of plates through different climatic zones allows new habitats to present themselves, and allow for different adaptations. APPLY Explain how plate tectonics has influenced evolution and biodiversity. Give specific examples. Mass Extinction Evolution Extinction Extinction is the process by which a species, genus, or family, becomes extinct — no longer existing and living in the world 99% of all species that were on earth no longer exist Mass Extinctions There have been several major extinctions since the beginning of life 3.5 billion years ago Evolution Extinction Background Extinction Not fit for the environment Mass Extinction More than ½ of the species extinct in 2 million years End of Ordovician (440 mya) 2nd most devestating in Earth’s history Effecting marine species Probably due to glaciation Source:http://www.palaeos.com/Paleozoic/Ordovician/Ordovician.htm Late Permian (225 mya) Largest extinction estimated that as many as 95% of all marine species were lost Possible causes continents merging to form Pangea global warming caused by volcanic eruptions glaciation Source: http://www.palaeos.org/Permian Cretaceous/Tertiary Extinction All dinosaurs and half of other animals and plants went extinct. Possible asteroid Brought about the rise of the mammals Mass Extinction Plate Tectonics Super Volcanoes Climate Changes Meteorite Impacts th 6 Extinction There are have been at least 5 in the history of the Earth so far, and it has been well argued that we are currently in the midst of a 6th mass extinction event, the Holocene extinction, or alternately, the Anthropocene extinction th 6 Extinction Past extinction were geological and extra terrestrial This is Human Caused. Must shorter time period Last 2-300 year loss is compared to 2-3 million years Discussion Question Why does Australia have such strange animals?? Evolutionary Timeline of mammals Platypus (Monotreme) Kangaroo (Marsupial) Dingo (Placental Mammal)
