Ecology & the Flow of Energy in the Ecosystem

Ecology The study of the interactions of organisms with one another and their physical environment

Both biotic and abiotic factors in a large area Ecosystem A self-sustaining collection of organisms and their physical environment Both biotic and abiotic factors in a large area                                                     

Biotic & Abiotic Factors Living organisms Abiotic = Nonliving Soil,Air,Water

Energy in Ecosystems Energy flows into the biological world from the SUN, the ultimate source of all energy.

Producers Producers are autotrophs… they can make their own food through photosynthesis Plants, some bacteria and algae

Consumers Eat other organisms to obtain energy Example: cows, humans…

Detrivores Organisms that obtain energy by eating organic wastes or dead bodies. Ex. Vultures http://montereybay.com/creagrus/vultures.html http://www.slivoski.com/birding/birds/turkeyvulture.htm

Decomposers Break down organic wastes (feces, urine, dead leaves or bodies) and cause decay. Receive energy from every other type Responsible for the final step in the food chain Example: Earthworms, maggots, fungi, and some bacteria

How is energy passed along an ecosystem? Pyramid of Energy Trophic Levels: Movement of energy through an ecosystem Levels of energy away from the sun (ulitmate source of energy) Who eats who in the food chain Shown as food chains, webs & pyramids

Food Pyramid 3rd Trophic Level – animals that feed on plant eaters or other flesh eaters (carnivores) Ex - Tiger - omnivores eat both plants & animals. Ex - humans 2nd Trophic Level – animals that eat plants (herbivores) Ex - cow 1st Trophic Level – producers/autotrophs Ex - plants On average, only 10% of the energy in any trophic level will be transferred to the next level.

Food Pyramid Tertiary consumer Secondary consumer Primary consumer Producers

Food Chains & Food Webs Most animals feed on more than one trophic level and feed on several different species at each trophic level. Making up a food chain and eventually a food web.

Food Chain ONLY ONE source of food Less stable

Food Web More than one choice of food Several food chains linked together More stable More Common

Population Ecology

Population Number of Individuals Same Species Live together in one area or place

What dynamics might be involved in predicting population growth? Population Size Population Growth Rate Carrying Capacity Limiting Factors

Population Size Number of individuals in a population Growth occurs when the birthrate is greater than the death rate.

Population Growth Curves Exponential growth: Population increases by a constant proportion per unit of time At this growth rate the population exhibits a J-shaped curve

Population Growth Curves Logistic growth: Population increases rapidly for a period of time, its growth begins to slow, and ultimately, growth stops. At this growth rate the population exhibits an S-shaped curve. K (carrying capacity) = maximum population size that an environment can support K

Factors That Control Population Growth Populations don’t grow indefinitely because of Limiting factors. Limiting Factors: Competition Predation Parasitism Crowding Stress Disease

Competition Situation in which two or more organisms attempt to use the same scarce resource (this could be a food source, a good location for capturing sunlight by plants, a particular nutrient, etc…)

Predation A relationship between two organisms in which one organism (predator) kills and devours another organism (prey).

Parasitism: The relationship between two organisms where one organism benefits (parasite) and the other is harmed (host). Example: Tapeworm You are harmed because it lives off your intestinal fluids Segments break off to form a new worm!

Biodiversity The number of species living within an ecosystem.

How Populations Evolve Hardy-Weinberg Principle The frequencies of alleles in a population do not change unless evolutionary forces act on the population. p2 + 2pq + q2 = 1

How Biodiversity Impacts Population Growth 6 forces that cause populations to evolve: Mutation – ultimate source of all variation Migration – movement of organisms from one population to another, creates gene flow. Nonrandom mating – when individuals prefer to mate with others of their own genotype, inbreeding is an example. Genetic drift – random change in response to their environment. Natural selection –Survival of the fittest. Extinction- species that have disappeared permanently.

Organism Interrelationships

Organism Interrelationships: Symbiosis= a close long term relationship between two or more species Beneficial: Mutualism= Both benefit Commensalism= Only one benefits & other is not harmed or helped Harmful: Parasitism= One benefits & Host slowly harmed

Mutualism Lichen=Fungus + algae Fungi carbon dioxide moisture Algae (Both Benefit) Lichen=Fungus + algae Fungi carbon dioxide moisture Algae food Oxygen

Commensalism (One Benefits) Whale unharmed Barnacles Protection from predators Transportation to new food sources

Commensalism (One Benefits) Clown fish dwell among the tentacles of tropical sea anemones. The anemomes are capable of stinging most fishes, but the clown fish possess a special mucous coating that somehow prevents the discharge of the anemone's stinging cells. The fish is protected from predators by the stinging cells.

Parasitism: The relationship between two organisms where one organism benefits (parasite) and the other is harmed (host). Example: Tapeworm You are harmed because it lives off your intestinal fluids Segments break off to form a new worm!

Cycles

Cycles within Ecosystems Almost everything within an ecosystem is recycled. Water, carbon, nitrogen & phosphorus pass from the nonliving environment to living organisms & then back to the environment.

Water Cycle Water is the most important, non-living component of the ecosystem. Nonliving cycle: involves condensation, precipitation, & evaporation. Living cycle: involves plants in a process called transpiration.

Human Impact on the Environment

Human Impact on the Environment How much trash do you think you throw away? How many times a day does a person pollute the environment? How many lakes and forests are killed by acid rain?

Pollution Pollution is anything potentially harmful that humans add to the environment. Pollution can drastically damage the health of ecosystems as well as the health of human beings.

Air Pollution Mainly caused by the burning of fossil fuels. Many forms: - Carbon Monoxide - Nitrogen Oxide

The Ozone Layer Consists of a layer of gas that is responsible for keeping UV radiation from reaching the earth’s surface. It is being destroyed by chlorofluorocarbons (CFC’s) CFC’s found in coolant in refrigerators & air conditioners, and the propellant in aerosol cans. 1 chlorine molecule destroys 100,000 ozone molecules.

The Ozone Layer

Acid Rain and Our Nation’s Capital Occurs when air pollutants get mixed with rain in the atmosphere. The product is sulfuric acid which is falls back to earth in rain and snow. Pure water has a pH of 7.0 (neutral) Normal rain has a pH of about 5.6. Acid rain has a pH below the 5.6 Avg. The pH in northeast US is 3.8. Acid Rain and Our Nation’s Capital Marble surfaces exposed to acid rain develop a rough "sugary" texture because the calcite grains are loosened as the edges dissolve in the rain water. Column capital volute, Jefferson Memorial, Washington, D.C.

Acid Rain NaOH

Greenhouse Effect Caused when sunlight reflected from earth’s surface is trapped as heat by carbon dioxide gas. Scientists predict an average temperature increase of 1-5 degrees C by 2050. How does this impact the environment?

Resources Renewable resources: Resources that replenish themselves naturally. Example: Trees Nonrenewable resources: Resources that do not replenish themselves naturally. Examples: Extinct species Fossil fuels such as oil and gas Trees are a renewable resource, but a forest ecosystem is nonrenewable. Why? New trees can be planted and grown to replace those cut down, but an ecosystem involves a complex web of relationships that are established over very long periods of time.

How pollution effects our Resources Pollution has led to a rapid draining of fuel supplies. The known reserves of oil and natural gas will be nearly depleted by the middle of the next century. Fossil fuels are nonrenewable resources. Nonrenewable resources do not replenish themselves naturally, whereas renewable resources do.

Solutions to Pollution Reduce pollution by proper waste disposal and recycling Conserve nonrenewable resources Reduce consumption of natural resources Conserve energy Curbing human population growth

Waste disposal & Recycling Solutions: Recycle as much as possible Aluminum products Glass containers Office & school paper Newspaper Many plastic materials Buy products that contain recycled materials Properly dispose of toxic and hazardous materials Household insecticides Oven cleaners Furniture cleaners Oil-based paint Motor batteries & oil Each year, Americans generate 153 million tons of garbage. This is dumped into landfills or is burned creating air pollution.

Conserving Nonrenewable Resources Topsoil for Agriculture The world has lost ¼ of its topsoil due to erosion from clearing of trees and vegetation and cultivating crops. Ground water (water trapped beneath the soil) Groundwater is being depleted by watering lawns, washing cars, and running fountains. It is also being polluted by poor disposal of chemical wastes. Species are disappearing. About 1/2 of the world’s tropical rainforests have been destroyed. At this rate, most of the world’s rainforests will be gone in 40 years. It is estimated that 1/5 or more of the world’s species will become extinct, mope than a million species lost, if the rainforests are destroyed.