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Ecology Unit Chapter 2: Principles of Ecology

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1 Ecology Unit Chapter 2: Principles of Ecology
Chapter 3: Communities, Biomes and Ecosystems Chapter 4: Population Ecology Chapter 5: Biodiversity and Conservation

2 2.1 organisms and their relationships
Ecology – scientific study of all the relationships that occur between organisms and their environment The word ecology was first introduced in 1866 by a German biologist named Ernst Haeckel.

3 Biotic and abiotic factors
Biotic factors – living factors in an organism’s environment Examples - ? Abiotic factors – nonliving factors in an organism’s environment Examples – temperature, air currents, water currents, sunlight, soil, rainfall

4 Levels of organization
Biosphere – portion of Earth that supports life Ecologists look at smaller portions of the biosphere when studying ecological relationships interactive levels of org (look at p 37) Biome Ecosystem Community Population Organism

5 Ecosystem interactions
Habitat – an area where an organism lives Niche – role or position that an organism has in its environment. An organism’s niche describes how it meets its needs for food, shelter and reproduction

6 What organisms are in this habitat?

7 Community Interactions
Competition – more than one organism uses a resource at the same time Resources are necessary for life and might include food, water, space, light, and mates Predation – the act of one organism consuming another

8 Mutualism – relationship between two or more organisms that live closely together and benefit from each other Commensalism – relationship in which one organism benefits and the other organism is neither helped nor harmed Parasitism – relationship in which one organism benefits at the expense of another organism

9 2.2 Flow of energy Organisms differ in how they obtain energy
Everything that organisms do in ecosystems requires energy. Where do organisms get their energy? From the Sun (of course)!!

10 Autotroph – an organism that collects energy from sunlight to produce food
Autotrophs are also called producers Autotrophs capture energy from the Sun, making it available for all members of an ecosystem Heterotroph – an organism that gets its energy by consuming other organisms Heterotrophs are also called consumers Herbivores eat only plants Carnivores prey on other heterotrophs for food Omnivores eat both plants and animals Detritivores eat dead, decaying material Decomposers break down dead material by releasing digestive enzymes

11 Models of energy flow Ecologists use food chains and food webs to model the energy flow through an ecosystem Food chain – a single, straight-line path of energy that involves only 4-5 organisms Food web - a bunch of food chains put together for a given habitat. Each step in a food chain or food web is called a trophic level Autotrophs make up the first trophic level Heterotrophs make up the remaining levels

12 Food Chains Vs. Food Webs

13 Loss of energy in a food chain
When an organism eats, almost half of the energy in the food is lost to the environment as heat. The amount of useful energy available to do work decreases as energy passes through the ecosystem Rule of 10 Only 1/10 (10%) of energy is used by an organism when it eats The other 90% is lost to the environment

14 Energy Pyramids An energy pyramid is a diagram that shows 3- 4 trophic levels The size of each block is determined by the amount of energy available

15 2.3 Cycling materials There are 4 different cycles that we find in the environment Water, carbon, phosphorus, and nitrogen A cycle is a pathway that describes how a chemical moves A substance enters a living organism The substance may stay in the organism for some time That same substance eventually leaves the organism and returns to the environment

16 The water cycle is very important to living things!!
Freshwater constitutes only about 3% of all water on Earth Water available for living organisms is about 31% of all freshwater 69 % of all freshwater is found in ice caps and glaciers Even ocean-dwelling organisms rely on freshwater flowing to oceans to prevent high salt concentrations inside their body.

17 Steps: Evaporation from bodies of water and/or transpiration from plants Condensation in the form of clouds Precipitation that falls as snow, rain, sleet, hail, etc. Some precipitation is absorbed by the soil and stored as ground water. Refer to page 46 interactive water cycle

18 The carbon cycle Carbon dioxide is absorbed by plants to make their own food and produce oxygen Carbon dioxide is released into the atmosphere in two ways: Respiration-breathing Combustion-burning of fossil fuels What is a fossil fuel? List several types of fossil fuels interactive carbon cycle

19 The Carbon cycle

20 3.1 Community ecology Community – a group of interacting populations that occupy the same area at the same time Limiting factor – any abiotic or biotic factor that restricts the numbers, reproduction or distribution of organisms in a community Examples include: sunlight, climate, water, temperature, nutrients, fire, soil, space If the environment of the community changes, plants and animals have to: Adapt in order to survive Migrate to a place that has resources

21 What organisms would you expect to find here?

22 Succession Ecosystems are constantly changing
A tree falls in the forest A forest fire wipes out a large community Ecological succession – the change in an ecosystem that happens when one community replaces another as a result of changing abiotic and biotic factors

23 Two types of succession
Primary succession A change in the environment that allows an area of land to support living things where it never did before Examples: melting glaciers, volcano Secondary succession A major (sometimes drastic) change in the environment that destroys much of what was living but allows for growth years later. Examples: tornado, hurricane, forest fire, flood, windstorm

24 Primary or secondary succession?

25 Primary or secondary succession?

26 3.2 Terrestrial biomes Weather – condition of the atmosphere at a specific place and time. Important elements of weather: Temperature Most organisms live best within a certain range of temperatures There are three major climate zones: tropical, temperate and arctic Moisture All organisms require water, so they must find a place to live that satisfies their needs. Elevation and ocean currents Visualizing Global Effects on Climate (p 67)

27 Be familiar with… Major land biomes pp 68-72 Mountains p 72
Polar regions p 73 Freshwater ecosystems pp 74-77 Wetlands p 78 Estuaries p 78 Marine ecosystems p 79-81

28 4.1 Population dynamics All species occur in groups called populations
Populations are characterized by: Population density – the number of organisms in a given area Spatial distribution – the pattern of spacing of a population Three types: uniform, clumped, random Visualizing Population Characteristics (p 93) Population ranges

29 Factors that limit Populations
Density-independent factors – any factor in the environment that does not depend on the number of members in a population Examples: drought, flooding, extreme heat or cold, tornadoes, hurricanes Density-dependent factors – any factor in the environment that depends on the number of members in the population Examples: predation, disease, parasites, and competition (see next slide)


31 Population growth rate
PGR – how fast a given population grows Dependent on birth rate and death rate If a population has more births then deaths, the population is ______________ If a population experiences more deaths then births, the population is ____________ If a population has an equal number of births to deaths, the population is _____________ Also dependent on emigration and immigration Emigration – describes the number of people moving away from a population Immigration – describes the number of people moving into a population

32 Population growth curves
Exponential growth curve (j-curve) Occurs when the growth rate is proportional to the size of the population All populations grow exponentially until some limiting factor slows the population’s growth. Logistic growth curve (s-curve) Occurs when the population’s growth slows or stops following exponential growth when the population reaches it’s carrying capacity. Carrying capacity – the maximum number of individuals in a species that an environment can support for the long term.

33 Growth curves Exponential Growth (J-curve) Logistic Growth (S-curve)

34 Boom & Bust Population Crash Oscillation Below Carrying Capacity

35 4.2 Human Population 1804 – estimated 1 billion people
Demography – the study of human population size, density, distribution, movement, birth rate and death rate. 1804 – estimated 1 billion people 1999 – 6 billion people 2011 – 7 billion people 2020 – projected to be 8 billion people

36 This looks like a J-curve, right
This looks like a J-curve, right? At what point to we reach carrying capacity?

37 Why are people living longer?
Agriculture has improved, allowing more people to be fed by large crops (corn, soybeans, wheat, etc). The breeding of animals (cows, pigs, chickens, etc) has increased food supplies. Technology has given people more information at their fingertips. Medications and vaccines have increased a person’s chance for survival by reducing the number of deaths from parasites and disease. Improvements in shelter have helped people survive major weather disasters.

38 Population pyramids Population pyramids show the age structure of a given population. The age structure is the number of males and females in each of three categories: Pre-reproductive: ages 0-19 Reproductive: ages 20-44 Post-reproductive: ages population pyramid animation

39 Human carrying capacity
Many scientists suggest that human population growth needs to be reduced. In many countries, voluntary population control is occurring. In other countries, “mandatory” population control is occurring. If human population continues to grow: areas become overcrowded and disease and starvation will occur natural resources become scarce (p 105)

40 5.1 Biodiversity Biodiversity is the variety of life in an area that is determined by the number of different species in that area. The importance of biodiversity Economic value Humans depend on plants and animals for food, clothing, energy, and shelter Medical/scientific value Medicines are derived from plants and animals The Madagascar periwinkle produces and extract that has been used with leukemia patients to increase survival (p 119) Aesthetic value Plants and animals give us a better appreciation



43 5.2 Threats to Biodiversity
Scientists believe we are witnessing a period of mass extinction—an event in which a large percentage of all living species become extinct in a short period of time. The current high rate of extinction is due to the activities of one species – HUMANS. Humans are changing conditions on Earth so fast that it doesn’t allow other organisms to adapt and survive.

44 Overexploitation Taking more individuals from a population than the species can replace. Bison were hunted to near extinction for their meat and fur Passenger pigeons went extinct in the early 1900s due to overhunting and urbanization The ocelot is hunted for the high value of its fur Rhinos are in danger of becoming extinct because of poachers who kill them for the horns on their head

45 Habitat loss Humans are clearing areas of land for housing and are replacing native plants with food crops. The tropical rainforests contain much of the world’s biodiversity. Removal of the forest will cause many species to become extinct. Natural disasters can cause disruption of habitats which in turn destroy food webs.

46 Pollution Pollution changes the composition of air, soil, and water for all animals. There are lots of toxic substances put into the air or dumped into the water or soil. Many of these substances accumulate in the tissues of living organisms. Biological magnification describes the increasing concentration of toxic substances in organisms as trophic levels increase in food webs. More and more news articles talk about mercury levels in fish. The more mercury in the water, the more mercury in fish tissue, the more mercury we consume when we eat fish.

47 Introduced species Nonnative species that are either intentionally or unintentionally transported to a new habitat are a threat to native species living in that area. Lamprey of the Great Lakes Asian long-horned beetle Emerald ash borer

48 Acid Precipitation When fossil fuels are burned, compounds called sulfur dioxide and nitrogen oxide are released into the atmosphere. These compounds react with water and form acids that fall back to Earth in the form of precipitation. More heavily populated areas have heavier amounts of acid rain. Aquatic animals and plants slowly die from acidic levels in the water, forests are burned, animals are forced from their homes.

49 Eutrophication Occurs when fertilizers, animal waste, and sewage rich in nitrogen and phosphorus flow into waterways, causing algae growth. The algae use all the oxygen in the water and suffocate plants and other aquatic species.

50 Protecting the Ozone Layer
Ozone is a compound made up of 3 oxygen molecules The ozone layer is important because it protects living things from ultraviolet (UV) radiation The ozone concentration is much lower over Antarctica What destroys ozone? CFCs = cloroflourocarbons found in coolants of old refrigerators and air conditioners also found in aerosol chemicals of spray cans VOCs = volatile organic compounds found in paints and varnishes, glue, caulk, air fresheners, cleaning and disinfecting products

51 Controlling Greenhouse gases
Human activity causes gases to be released into the atmosphere. These gases trap solar energy and help to insulate the Earth just like a greenhouse traps heat from the Sun.

52 Greenhouse gases include:
Water vapor, carbon dioxide, and methane Because humans still burn fossil fuels, carbon dioxide levels get higher and higher. When water vapor and carbon dioxide are mixed in the atmosphere they trap the solar energy and contribute to the Earth’s rising temperature. All of this trapped heat energy causes changes to weather patterns, making storms more severe across the globe. Some of this trapped heat also causes the ice to melt (glaciers, ice sheets) at the north and south poles.

53 Protecting Fresh water
Freshwater is in short supply because humans pollute this very important resource How can you conserve water in your home?

54 The total usable freshwater supply for ecosystems and humans is less than 1 percent of all freshwater resources. By 2025, 1.8 million people will be living in countries or regions with absolute water scarcity, and two-thirds of the world population could be under stress conditions.

55 The UN suggests that each person needs liters of safe freshwater a day to ensure their basic needs for drinking, cooking and cleaning. More than one in six people worldwide million - don't have access to this amount of safe freshwater. Globally, diarrhea is the leading cause of illness and death, and 88 percent of diarrheal deaths are due to a lack of access to sanitation facilities. Today 2.5 billion people, including almost one billion children, live without even basic sanitation. Every 20 seconds, a child dies as a result of poor sanitation. That's 1.5 million preventable deaths each year.

56 The daily drinking water requirement per person is 2-4 liters, but it takes 2000 to 4000 liters of water to produce one person's daily food. In 2007, the estimated number of undernourished people worldwide was 923 million. By 2050, the world's water will have to support the agricultural systems that will feed an additional 2.7 billion people. Every day, 2 million tons of human waste are disposed of in waterways. In developing countries, 70 percent of industrial wastes are dumped untreated into waters where they pollute the usable water supply.

57 5.3 Conserving biodiversity
As population increases, the need for natural resources also increases, but usually at the expense of harming other species. Visualizing biodiversity hot spots Nonrenewable resources are found in limited amounts and must be used carefully. Fossil fuels, minerals, water Renewable resources have an endless supply Solar, wind More people need to live sustainably Reduce the amount of resources consumed Recycle resources that can be recycled Take resources from an ecosystem responsibly


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