Natural Causes of Extinction

Natural Causes of Extinction for Grade 9 Students

1. NATURAL CAUSES OF EXTINCTION BY SIR OSCAR MARTINEZ GUZMAN, JR. SCIENCE TEACHER CALACA ACADEMY INC. Admana St. Pob 2. Calaca, Batangas Philippines Earth and Life Sciences/Earth Science [email protected] www.facebook.com/JrMartinez [phone] [phone]

2. Diverse forms of organisms become extinct due to the following natural causes. Genetics and demographics If a population becomes small for any reason, the members of the population become more inbred, further reducing population size.

3. A smaller population also loses genetic diversity because of inbreeding and suffers reduction in the ability to adapt to the changing environment. 2. Uncontrolled predation. Animals becomes extinct when exotic or non-native species are introduce to a new habitat. If they have no natural enemies in their new habitat, then their prey eventually becomes extinct.

4. 3. Coextinction The loss of one species leads to the loss of another. It becomes a chain of extinction. For example, when a prey loses its food source, its population decreases. Therefore, its predators have lesser food to eat; hence, the population of predators also decreases.

5. 4. Mass extinction This refers to the sharp decreases in the number of species on Earth in a short period of time. These are caused by asteroids impacts, climate change, and other catastrophic events on Earth.

6. 5. Climatic heating and cooling T his natural event has a very significant effect of extinction. Many species are not used to severe weather conditions and long seasons or a changing chemical makeup of their surroundings.

7. 6. Change in sea levels. The spreading of the ocean floor causes the rising of the sea levels. Therefore, a significant amount of water can displace onto the land that is already occupied. Gases from volcanic activities can also be absorbed by the water, thus changing its chemical composition. Eventually, water may become unsuitable for some forms of life.

8. 7. Acid rain This increases the acidity of the soil which affects plants and lakes to possibly lethal levels. Aside from the natural causes of acid rain, human activities have led to the presence of certain chemicals in the atmosphere that contributes to the formation of the acid rain.

9. Characteristics of species vulnerable to extinction Large species with low reproductive potential such as whales, rhinos, great apes, condors, and whooping cranes. Species with high economic vales such as whales, sea turtles, elephants, spotted cats, and rhinoceroses.`

10. 3. Species at the end of long food chains such as birds of prey, cats, and reptiles. 4. Species restricted to local, insular habitats such as snail darters and key deer. 5. Highly specialized species such as giant pandas and black-footed ferrets. 6. Migratory species such as monarch butterflies, marine mammals, and many birds.