Chapter 18
What is Ecology? The study of the interactions between organisms and the living (biotic) and nonliving (abiotic) components of their environment.
What is Biodiversity? Biodiversity is the sum total of different kinds of organisms and their environments. Biodiversity can be affected by alterations of habitats.
What is Biodiversity? Ex: Climate change affects air and ocean temperatures, the length of seasons, sea levels, the pattern of ocean and wind currents, levels of precipitation, as well as other things. These changes affect the habitats and behavior of many different species. This interconnectedness is called interdependence
What is Interdependence? INTERDEPENDENCE- Describes the fact that all organisms interact with other organisms in their surroundings and with the nonliving portions of their environment. Their survival depends upon these interactions.
Consequences A consequence of interdependence and interconnectedness is that any disturbance or change in the ecosystem can spread through the network of interactions and affect the entire ecosystem in often negative ways.
Ecological Models Ecologists construct models to help them understand the environment and make predictions about how the environment might change. Models can be used to: a. test hypotheses about ecosystems b. Make predictions about how the environment might change.
Levels of Organization A. Biosphere: The broadest, most inclusive level of organization. The thin volume of Earth and its atmosphere that supports life; all organisms are found within the biosphere. Organisms are found: 1. Land and Soil 2. Water 3. Lower Atmosphere B. Ecosystem - includes all of the organisms and the non-living environment found in a particular place. (e.g. A pond)
Levels of Organization C. Community - all the interacting organisms living in an area (e.g. all the fish, turtles, plants, algae, & bacteria in the pond) D. Population -includes all the members of a species that live in one place at one time. E. Organism: one specific member of a population.
The Ecology of Organism Ecologists can learn a lot about organisms by studying them in their habitat, or where they live.
Ecologists separate the environmental factors that influence organisms into two classes: Factors Biotic Abiotic
What do you think bio means? Official definition of biotic: of, relating to, or caused by living organisms; biotic diversity
The prefix a means Bio means Official definition of abiotic: Nonliving, as in abiotic factor, which is a nonliving physical and chemical attribute of a system, for example light, temperature, wind patterns, rocks, soil, ph, pressure, etc. in an environment.
Abiotic factors are not constant, they vary from place to place
How do organisms respond to a changing environment? Some organisms are able to survive within a wide range of environmental conditions. Some organisms are adapted to function within a specific range of conditions, such as temperature.
Ecologists determine a range for an organism by measuring how efficiently it performs at different variables.
Responding to the Changing Environment A graph of performance versus values of an environmental variable, such as temperature is called a Tolerance Curve.
Changing Environment Some organisms can adjust their tolerance to abiotic factors through a process called acclimation. Ex: goldfish raised at different temperatures, humans in high altitudes
Changing Environment 8. Environments constantly fluctuate in temperature, light, moisture, salinity, and other chemical factors. There are two ways for organisms to deal with changes in their environment.
A. Conformers - organisms that do not regulate their internal conditions; they change as their external environment changes. e.g. snakes and lizards (cold-blooded) B. Regulators - organisms that use energy to control some of their internal conditions; they can keep an internal condition within the optimal range over a wide variety of environment conditions. e.g.mammals and birds (warm-blooded)
9. How do species survive an unfavorable environment? Some species can survive unfavorable environmental conditions by escaping from them temporarily. Some animals enter a state of reduced activity called dormancy. e.g Winter=Hibernation--> Bears Summer= Estivation--> Frogs
How do species survive an unfavorable environment? Some species move or migrate to another, more favorable habitat. e.g. Birds, Geese, Gray Whale, Butterflies
How do species survive an unfavorable environment? Whether a species can survive in a particular habitat depends on the suitability of environmental conditions and also on the availability of resources. e.g. Food, water, shelter, temperature, amount of sunlight
10. The Niche An organisms way of life, or role it plays in its environment.
The Niche 1. Fundamental Niche - the range of conditions that a species can potentially tolerate and the range of resources it can potentially use. 2. Realized Niche - the range of resources a species actually uses. Usually much narrower than the fundamental niche.
The Niche 3.Generalists - species with broad niches who can tolerate a wide range of conditions and can use a variety of resources. EX: Virginia Opossum, raccoon, rats, goats 4. Specialist - species with narrow niches. EX: Koala Bears, Panda Bears
11. Energy Transfer Energy Transfer- All organisms need energy to carry out essential functions such as: growth movement maintenance and repair and reproduction.
12. Where does all energy originate? A. In an ecosystem energy flows from the sun to the producers or autotrophs then to the organisms that eat the autotrophs, and then to the organisms that feed on the other organisms.
13. What is a trophic level? A Trophic Level indicates an organism s position in a sequence of energy transfers.
14. What is a food producer? 14. Food Producers-(Autotrophic) make their own food using solar or chemical energy through the process of photosynthesis e.g. green plants, algae, bacteria ***some bacteria carry out chemosynthesis which means they produce carbohydrates by using energy from inorganic molecules.
15. How do we measure productivity of autotrophs? A. Gross primary productivity: is the rate at which producers in an ecosystem capture the energy of sunlight by producing organic compounds.
Producers use energy they capture to make sugar and other organic molecules which is called biomass.
Only energy stored as biomass is available to other organisms in the ecosystem.
B. Net primary productivity: the rate at which biomass accumulates in an ecosystem. *it is typically expressed in units of energy per unit area per year (kcal/m 2 /yr) or in units of dry organic mass per unit area per year (g/m 2 /yr) * the ecosystem with the highest net productivity is the tropical rain forest
16. What are food consumers and decomposers? Food Consumers -(Heterotrophs) cannot make their own food; feed on plants and animals and organic wastes. a. Herbivores -eat only plants b. Carnivores -eat only animals (meat) c. Omnivores -eat plants and animals
Decomposers Scavengers or Detritivores -consumers that feed on dead organisms; other organisms kill. Important in recycling chemicals. e.g. vulture, crayfish, snails Decomposers- organisms that break down (decay) dead tissues and wastes into nitrogen, carbon, and phosphorous. Some of these molecules are absorbed by the decomposers and some of them are returned to the soil or water. Ex. bacteria, fungi
Decomposers/Scavengers Decomposers and scavengers help break down dead plants, animals, and waste products from organisms. They are an important part of an ecosystem. If they did not exist, the biogeochemical cycles would not occur and dead matter and wastes would accumulate in the environment. A vital part of an ecosystem is the stability of its producers and decomposers/scavengers.
17. What is a food chain? A Food Chain is a single pathway of feeding relationships among organisms in an ecosystem that results in energy transfer an example of a food chain would be:
Food Chain 18. The specific sequence in a food chain is: 1. Producers 2. Primary consumers 3. Secondary consumers 4. Tertiary consumer/ Quaternary consumer 5. Scavenger and/or Decomposer
19. Food Web All the interrelated food chains in an ecosystem are called a Food Web. -The feeding relationships in an ecosystem are usually too complex to be represented by a single food chain. - Many consumers eat more than one type of food and more than one species of consumer may feed on the same organism.
20. How does energy transfer in trophic levels? Most food chains only consist of few trophic levels because only about 10% of the energy available at one level is transferred to the next level. Organisms at the bottom of the food chain are usually much more abundant than organisms at the highest level.
21. Energy pyramids This energy transfer can be seen in the diagram below. The pyramid shape of the diagram indicates the low percentage of energy transfer from one level to the next.
21. Energy pyramid Only 10% of the energy is passed on to the next trophic level and 90% of the energy is used for life processes (ex: respiration, digestion) or dissipates in the environment as heat.
On a separate piece of paper: Create a food chain energy pyramid using the 5 trophic levels (see #18). Use a different chain than in your notes.
Make sure you label the trophic level and the organisms.
Label the amount of available energy at each trophic level. Start with 1,000,000 kcal (only 10% of the energy is passed on to the next trophic level).
Answer the following questions with complete sentences. Remember to incorporate the question in your answer. 1. Why are there fewer consumers at the top of the energy pyramid? 2. What role does the sun play in the ecosystem? 3. Why is there energy lost between feeding levels? 4. Why are producers essential to the ecosystem?
5. Compare the trophic level of the killer whale when it feeds on the penguin to the elephant seal.
6. What level of consumer would have the greatest population in the ecosystem? Explain. 7. What level of consumer would have the least population in the ecosystem? Explain.
22. What are biogeochemical cycles? Biogeochemical cycles include the water, carbon, and nitrogen cycles. They are important because they recycle and reuse energy and matter in an ecosystem.
23. Water Cycle The availability of water is one of the key factors that regulate the productivity of terrestrial (land) ecosystems. The movement of water from the atmosphere to the earth and back again is called the water cycle.
23. The Water Cycle The processes involved in the water cycle are: a) Precipitation-water moves from the atmosphere to the earth in the form of rain, snow, and hail. b) Evaporation- water moves from the earth to the atmosphere. c) Transpiration- process where plants lose or evaporate water through pores in their leaves called stomata. d) Percolation- process where water soaks into the soil or in underground formations of porous rock; it is then called groundwater.
24. The Water Cycle Water on the surface of the earth in the form of streams, rivers, ponds, and lakes is called Run-off water. As water soaks into the ground, its level rises underground, creating a zone of saturation called the Water Table.
Problems with the Water Cycle The water available to planet Earth is the same water that has always been available and the only water that ever will be available. Water covers three-quarters of the earth s surface, it might appear that there is plenty to go around. In reality, however, we have a limited amount of usable fresh water.
Water Cycle As we attempt to meet the water use needs of a growing population, issues of water quality and quantity will gain increasing significance in years to come. We cannot afford to waste or pollute the small amount of fresh water we have.
25. The Carbon Cycle The carbon cycle involves the process of Photosynthesis & Respiration where the gases, oxygen and carbon dioxide are recycled through living organisms.
The Carbon Cycle 1. During photosynthesis plants use carbon dioxide, water and sunlight to make glucose. Oxygen is given off as a waste product.
The Carbon Cycle 2. During respiration plants & animals use oxygen to break down glucose for energy, and water and carbon dioxide are given off.
The Carbon Cycle 3. Decomposers release carbon dioxide into the atmosphere when they break down organic compounds.
The Carbon Cycle 4. Humans influence the carbon cycle by our burning of fossil fuels, (Coal, oil, & natural gas: combustion) which provides us with lots of energy but also releases large amounts of carbon dioxide; which contributes to Global Warming.
26. The Nitrogen Cycle All organisms need nitrogen to make proteins & nucleic acids. The atmosphere is mostly comprised of nitrogen gas. It must follow a complex pathway called Nitrogen Cycle in order to change nitrogen gas into useable nitrogen.
27. The Nitrogen Cycle Some processes involved in the nitrogen cycle are: 1.Nitrogen Fixation- Nitrogen gas (N 2 ) Ammonia (NH 3 ) The process of converting nitrogen gas (N 2 ) into ammonia (NH 3 ). This is done by bacteria found in the soil
Nitrogen Cycle 2. Ammonification Waste Nitrogen Ammonium (NH 4 ) The process of breaking down dead organisms and animal wastes. Bacteria, or in some cases, fungi, (decomposers) convert the organic nitrogen within the remains back into ammonium (NH 4 )
Nitrogen Cycle 3. Nitrification Ammonium (NH 4 ) nitrites (NO 2 ) + nitrates (NO 3 ) Bacteria in the soil transform the ammonia into nitrites (NO 2 ) and nitrates (NO 3 ) which plants can use to make amino acids.
Nitrogen Cycle Through assimilation, plants can absorb nitrate or ammonium ions from the soil via their root hairs. Animals obtain nitrogen by eating these plants then digesting the proteins and nucleic acids.
The Nitrogen Cycle 4. Denitrification- nitrites (NO 2 ) and nitrates nitrogen gas (N 2 ) The process in which nitrogen is returned to the atmosphere where anaerobic bacteria break down nitrates and nitrites and release nitrogen back into the atmosphere.
Problems with the Nitrogen Cycle Increasing the amount of nitrogen in the atmosphere (use of fertilizer, burning forests/wood, etc.) alters the global nitrogen cycle, causing serious impacts on biodiversity (soil acidification), global warming, water quality (acid rain), human health, and even the rate of population growth in developing nations.