Aim: How have humans negatively affected diversity in the environment?

Human Impact Although not the most numerous organisms on earth, humans have the greatest effect on the environment.

Why are humans disrupting the balance in ecosystems? The sheer number of people on this planet are putting a tremendous strain on the Earth’s environmental resources.

How did this rapid growth occur? 3 Increased Food Supply Improved Health Care Improved Sanitation and Hygiene

Carrying Capacity & Limiting Factors Carrying Capacity- is the number of individuals the environment can support. Limiting Factors- are factors in the environment that limit the size of populations. What are some of our limiting factors? Food, Water, Oxygen, Space

Carrying Capacity Time

Have we reached earth’s carrying capacity? No, because we continuously come up with new technologies to produce more _______ food.

How do humans usually impact the balance in ecosystems?

What are some of the detrimental effects of overpopulation? Technology Waste Disposal Over Consumption

What are some of the detrimental effects of overpopulation? Overcrowding Industrialization Habitat Destruction

Human Activities & the Loss Of Diversity: Deforestation Why clear cut forests? 1) Provide land for farming 2) Provide people places to live 3) Provide resources to use in building or manufacturing Effects: 1) Deforestation leads to habitat destruction. 2) Organisms can become endangered or extinct. 3) Biodiversity decreases.

Human Activities & the Loss of Diversity: Direct Harvesting Organisms (plants and animals) are removed from the environment and NOT replaced. Organisms are usually obtained through hunting or poaching (illegal hunting). Examples: What are they used for? Ivory, Shark Fins, Exotic Birds Often results in the loss or elimination of a species & a decrease in diversity.

Human Activities & the Loss of Diversity: Imported Species Non-native (not belonging to) animal and vegetation species often become invasive when introduced into environments lacking natural predators or other mechanisms to keep the dominating species in check. These species become pests & disrupt the current ecosystem by reducing diversity.

Australia’s Biggest Pest (26 in 1800s to billions) Highly adaptable animal. Not a picky eater and breeds very fast. Destroyed massive amounts of vegetation & reduced diversity. In Australia, it spread like wildfire because its natural predators from back home, the weasel and fox, were not originally present. The dingo and Tasmanian wolf, Australia's native carnivores(and potential rabbit consumers), were themselves being kept in check by local sheep and cattle ranchers. The European Rabbit

New York’s Biggest Pest: Gypsy Moth 8 The Gypsy Moth originally evolved in Asia & was introduced here accidentally in What can happen when non-native species are added to a new environment? 1) They often have no natural enemies. 2) Rapidly overpopulate. 3) They then crowd out, feed on, or otherwise eliminate native species. 4) Diversity decreases.

How do ecologists solve these pest problems? Disease Organism Specific for the Pest: A virus was promptly released into the wild in Australia and effectively spread like wildfire through mosquito and rabbit flea bites, and killed all but 0.2% of the rabbits. This small percentage had built a resistance to the virus, bred like rabbits, and passed on the resistance to the virus.

How do ecologists solve these pest problems? Use of Pesticides or Insecticides: These chemicals/poisons can kill the pest, but also other organisms native to the ecosystem.

How do ecologists solve these pest problems? The release of native predators of a pest species is a safe way to control pest problems. If a non-native predator is imported to control the pest, it may choose to feed on other native organisms reducing diversity.

What are the effects of farming? What happened to biodiversity? What happened to ecosystem stability? What would happen if an insect came along? What do farmers use to get rid of insects?

Biological Magnification The concentration of toxic substances (DDT) as you move through the food chain (plants are eaten by herbivores, which are eaten by carnivores, etc…..)