The Sixth Extinction? Topic 7 Biological Diversity

In the last 600 million years there have been five major declines in Earth’s biodiversity. The 6 th Extinction

Relative Species Diversity

Human Impact on Biodiversity Some areas of the world support more biodiversity than others. What factors influence diversity? –Heat –Light –Rainfall

Disappearing Habitats Bioindicator Species: a species in an ecosystem that when their population starts to decline indicate that there is a problem with the ecosystem.

Disappearing Habitats Grizzlies (and other large carnivores) are thought to be a bioindicator species. Grizzlies used to roam throughout North America. The disappearance of Grizzlies from Mexico and most of the United States is called extirpation.

Disappearing Habitats One of the first effects of human interference in an ecosystem is the loss of the large carnivores usually found in the ecosystem.

Human Impact on Rain Forest Ecosystems Human populations are growing more than ever before. Larger population increases demands on environment. –Natural habitats are being cleared for farming and housing. –Increases in logging and mining lead to increases in pollution.

Human Impact on Rain Forest Ecosystems Rain Forests are areas the highest bio diversity in the world. It is being cut down at a rate of about 1% per year.

The Population Explosion Population growth is not spread equally around the world. Developing nations are usually hardest hit by the population explosion. Space has to be cleared on the land to make space for the population growth. This leads to clearing of rain forests which can lead to extinction of some species.

Human Activities and Extinction Humans have not always been aware of their impact on the survival species as we are today. Technology has given us the ability to preserve biodiversity; but technology also has increased our ability to use up resources leading to damage to the environment.

Human Impacts –About years ago it is thought that humans hunted woolly mammoths to extinction. – Large animals have been almost hunted to extinction in Madagascar, Australia and New Zealand. –In the late 1800s Passenger Pigeons were hunted so much in the eastern North America that they went from the world’s most abundant bird to extinction in about 100 years.

Extinction