4.7.12.B

EFFECTS OF EXTINCTION ON THE ENVIRONMENT
** Below are just some of the issues that effect or are affected by the exctinction of species. **

BIODIVERSITY AND THE ENVIRONMENT
**Biodiversity** is the variability among living organisms from all sources, including, among other things, terrestrial, marine and  other ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems. The loss of biodiversity, in the world, grows everyday as more species decease. This threatens environmental, economical, and social goals. Recent studies, by Europa EC, have found that human activity has caused between 50 and 1000 times more extinctions in the last 100 years than would have happened due to natural processes and that this rate of loss is projected to accelerate 10-fold by 2050. The main causes of the loss of biodiversity are the changes in the natural habitats that once existed. Due to intensive agricultural systems, constuction and extractive industries, deforestation, exploitation of oceans, rivers, lakes, and soils, new invasive species to the habitat, pollution, and global warming, the conditions that species once lived in have been dramatically changed. This has caused multiple species to move to new locations for survival, disturbing the habitats of others and also ruining once precious ecosystems. "The loss of such biodiversity has many repercussions beyond the disappearance of individual species because of the broad variety of plants and animals required to sustain the natural cycles essential to human survival. For example, the interplay of freshwater plant and animal species keeps wetland ecosystems clean, and plants provide raw material for 25 per cent of the pharmaceuticals sold in the United States" (Nature Gallery, PacificIslandTravel.com).

** GLOBAL WARMING[[image:http://www.genersys.co.za/Images/2008/Environmental/global-warming-diagram.png align="right" caption="Global Warming from FreeFoto"]] **
**Global Warming** is a serious issue that is affecting over 200 species on earth, some even to the point of extinction. Both animal and plant species are in danger, changing sooner than predicted, and dying off (msnbc, msnbc.com, 2006). “This serious economic problem is caused by the emission of heat trapping gases produced by vehicles, power plants, industrial processes and deforestation”(The Nature Conservancy, nature.org, 2008). These emissions over heat the planet and threaten its health. It is also threatening many of the earth’s ecosystems that keep the earth in balance. It is changing the population sizes of both plants and animals, affecting their growth rates, the timing of migration for many species, and also the timing of plant flowering and reproduction. Global warming effects the “intensity and frequency of storms”, the rise and fall ocean levels, and the melting glaciers in the artic habitat. The earth’s climate is constantly changing and has been changing all throughout history. Ice ages, interglacial periods, and the extinction of countless numbers of species are a result of these climatic changes. Factors that affect the earth’s climate include changes in the earth’s orbit, changes in the sun’s intensity, volcanic eruptions containing aerosol and carbon dioxide emissions, changes in greenhouse gas concentrations, and changes in ocean currents. The major affects of global warming can be seen in areas of the far northern hemisphere of earth, for example, the Arctic. The cold- adapted species, Emperor Penguins and Polar Bears, have dramatically decreased in both size and number, some as drastically as dropping from 300 breeding pairs to nine (Emperor Penguins). Species that adapt to warmth are having an easier time with global warming. Migration patterns have changed for many, forcing some species to move farther north to "colder" regions

** POACHING **
Poaching is defined as the illegal hunting, capturing, or killing of animals. It is also a major problem facing the extinction and endangerment of species. Poaching usually happens in more inpoverished countries such as Africa. It is a serious problem because many of the animals that are hunted and killed      can be found on the endangered species list. For example, each year in Zimbabwe, hundreds of elephants are killed for their tusks which are made from ivory. This problem is still out of control. The poaching of animals is also quite common in areas like China where the tusks, bones, and other parts of the animal are used for medicines. In other areas, animals are trapped and then sold as pets in stores or sold to live on large ranches. Although poaching is such a serious problem, it is one that is hard to enfore. Many poachers are skilled at organized poaching which makes them hard to track, making enforcement of poaching laws nearly impossible.  media type="file" key="Overhunting_and_Poaching3.mov" width="367" height="297" (Unitedstreaming videos)

HABITAT DESTRUCTION
**Habitat destruction** is a problem that is growing larger every year. With the worlds growing population, developments takeover once plentiful forest areas. Deforestation consumes much of a species' habitat and is on the rise. The loss of many plant species plays a role in the diminishing animal populations. When a plant goes extinct, so does the food supply, and possibly shelter and breeding areas for certain creatures. This brings attention back to the House of Cards Analogy (can be found in standard A), and the dependency of one species on another. In today's world, population fragmentation walks hand in hand with habitat destruction. **Population fragmentation** is the splitting and consequent isolation of portions of populations by habitat degredation. Population fragmentation is mainly due to human activities such as logging and the building of communities and has a decreasing effect on the size and gene flow of a population. The fragments that result from fragmentation are called **subpopulations**. Usually, subpopulations vary in habitat and quality of the habitat. This has a great effect on the reproduction of species. For example, a high- quality subpopulation with the required shelter, food, and breeding grounds will have a higher rate of population than a low- quality subpopulation that lacks the essentials for a specific type of animal. The individuals in the high- quality subpopulation will produce more offspring which can result in a source habitat. A **source habitat** is an area of a habitat where a subpopulation's reproductive success exceeds its death rate. The opposite of a source habitat is a **sink habitat;** the death rate exceeds its reproductive success. Recently, more sink habitats have been more plentiful than source habitats which puts a great toll on the worlds variety of species, both plants and animals. media type="file" key="Habitat_Destruction.mov.part" width="300" height="300" (Unitedstreaming Videos)

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