RISE AND FALL UNIT 5 EVOLUTION

Rise and Fall The rise and fall of major groups of organisms have shaped the history of life Rise and fall rates are often related to speciation and extinction rates There can be a rise in a new group of species when the amount of births are greater than those lost to extinction

Rise and Fall Factors There are many factors that can affect the rise and fall of organisms… Plate Tectonics Mass Extinctions Adaptive Radiations

Plate Tectonics Plate Tectonics – the theory that Earth’s continents are part of big plates on Earth’s crust that float on the upper part of the mantle The outer layer of these plates is known as the “lithosphere” The movement of these plates can result in earthquakes and volcanoes Continental Drift – when movements in the mantle cause tectonic plates to move over time Mountains and islands are located at plate boundaries

Patterns of Continental Drift Plates can move away from each other Example – North American and Eurasian plate Plates can slide past each other Forming regions where earthquakes are common Example – The San Andreas Fault in California Plates can collide into each other Can cause the formation of mountains along plate boundaries Example – The Indian plate colliding into the Eurasian plate (forming the Himalayan Mountains)

Consequences of Continental Draft Can alter the habitat in which an organism lives in Can alter the physical environment and climate This can result in extinctions as well as new opportunities Can promote allopatric speciation When continents break apart, connected regions start to become isolated Can explain the geographic distribution of extinct and present-day organisms

Mass Extinctions Fossils show how majority of species have become extinct A species can become extinct for many reasons Destroyed Habitat Change in environment Temperature change The origin of one species can be the death of another species Mass Extinction – when large numbers of species become extinct worldwide

Mass Extinction Events In the past 500 million years, there have been 5 major mass extinctions There are two mass extinctions that have caused the most change in history Permian Mass Extinction Cretaceous Mass Extinction

Permian Mass Extinction Severely affected both aquatic and terrestrial life Affected 96% of marine animal species 8 out of 27 land insects were removed Occurred during extreme episodes of volcanic eruptions Volcanic eruptions produced enough carbon dioxide to warm the global climate and cause ocean acidification

Cretaceous Mass Extinction Occurred more than 65 million years ago Removed more than 50% of all marine species Known for causing the extinction of “dinosaurs” Researchers believe this extinction was caused because of a thin piece of clay made of “Iridium” Iridium is very rare on Earth, but very common in objects that fly towards Earth (meteorites, large comets, clouds, asteroids) Researchers believe that this “clay” is debris of a large comet or asteroid that collided into the Earth, causing this mass extinction

Consequences of Mass Extinctions Can cause an ecological community to disappear Takes 5-10 million years to recover the diversity of life Took 100 million years for marine families to recover after Permian mass extinction Can affect the organisms living in ecological communities Mass extinctions can result in adaptive radiation

Adaptive Radiation Adaptive Radiation – a period of evolutionary change in which organisms form new species whose adaptations allow them to fill different ecological roles Occurred on a large scale after the 5 mass extinctions Survivors of the mass extinction would adapt to the remaining ecological niches Common among organisms that face little competition from other species

Adaptive Radiations Worldwide Adaptive Radiation – adaptive radiations that occur on broad geographic areas around the world Example – the extinction of dinosaurs resulted in the expansion of mammals (both in diversity and size) to fill ecological roles occupied by dinosaurs Regional Adaptive Radiations – adaptive radiations that occur over limited geographic areas Occurs when organisms move to a location with little competition