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8-2.7 Summarize the factors, both natural and man-made, that can contribute to the extinction of a species. Extinction is forever!!. When is a species considered extinct?. If no members of that species are still alive. Most organisms that have ever lived on Earth are now extinct.
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8-2.7 Summarize the factors, both natural and man-made, that can contribute to the extinction of a species.
Extinctionis forever!! • When is a species considered extinct? • If no members of that species are still alive. • Most organisms that have ever lived on Earth are now extinct.
Mass Extinction • Sudden extinctions (confined to a few million years or less) which sweep away a large variety of living creatures. • Geologic time is marked by these events. • Paleozoic era ended theoretically because of a major climate shift. • Mesozoic era ended theoretically because an object from space struck Earth. • Cenozoic era continues today…..
Factors that contribute to extinction • Natural factors • Have caused extinctions throughout history. • Man-made factors • Have caused extinction in more recent times. • Brainstorm potential examples of each type.
On a clean sheet of paper (to be kept with notes). Set up the entire page as shown below. Natural factors Man-Made factors
Natural Factors • Organisms could not survive changes due to various natural events. • Natural extinctions have occurred throughout geologic history. • Not all extinctions have a negative impact. • They clear the way for new kinds of life.
Natural Factors of Extinction • Volcanic Activity • Huge lava flows that produced enormous amounts of ash. • The ash in the air altered the global climate and ocean chemistry.
Natural Factors of Extinction • Global Warming • Animals could not survive the extreme change in temperatures and climate. • Global Cooling (Ice Ages) • Cooling events caused Glaciation events • Ocean water would freeze and therefore lower the sea level.
Natural Factors of Extinction • Oxygen Depletion • As water cools, it causes dramatic shifts in limiting factors such as oxygen. • As oxygen levels in sea water were depleted, many species died out.
Natural Factors of Extinction • Asteroid or comet impact • The impact from a huge asteroid would have sent tidal waves across the earth and caused many fires. • Clouds of dust and ash would block the sunlight. • The planet would cool and plants and animals would die due to lack of sunlight. • The impact that killed the Dinosaurs was thought to have occurred in somewhere near Mexico.
Chalk Talk • Review of natural factors of extinction.
Man-made Factors of Extinction • Many plants and animals are likely to become extinct in the near future. • Humans remove survival needs of many organisms. • We are also threatening our own biological resources. • Man-made factors are damaging the Earth.
Man-made Factors of Extinction • Cutting of rainforests • Destroys habitats and food sources of many different animals. • Trees are logged for human needs.
Man-made Factors of Extinction • Removing of Natural Habitats • Cutting down rainforests, agricultural activities and houses for humans. • Animals have no where to live, breed and hunt.
Man-made Factors of Extinction • Over-harvesting or Hunting • Many animals have been hunted to extinction by humans. • Example, the Carolina Parakeet. • Lived in the southeastern United States. • Appeared 5 million years ago and became extinct in the early 1920’s from hunting.
Man-made Factors of Extinction • Pollution • Industrial activities have polluted rivers and oceans with toxic chemicals. • Introduction of foreign species • Sailors would bring domesticated animals to remote areas. (dogs, rats……) • These animals would kill native animals and compete for food sources.
Chalk Talk • Review of man-made factors of extinction.
KEY QUESTIONS 1. What is extinction? 2. What are some man-made factors that contribute to the extinction of plants and animals? 3. What are some natural phenomena that contributes to the extinction of plants and animals?
