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Ecology What is ecology? Ecology is the scientific study of the interactions of organisms with their environments Ecologists describe where organisms live and how many live there Ecologists look at variables that affect organisms. These variables are biotic and abiotic The biosphere contains the combined portions of the planet in which all of life exists, including: • land • water • air, or atmosphere The biosphere extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean. What is ecology? Biotic factors: living things in an environment examples include… Abiotic factors: nonliving things in an environment examples include… An organism’s habitat, includes both factors Habitat: where an organism lives Factors affecting life in a biosphere 1. Energy source – sunlight, chemicals (inorganic), food (organic) 2. Temperature – affects metabolism 3. Water – how much is needed depends on organism 4. Nutrients – nitrogen, phosphorus (in soil), pH 5. Other aquatic factors – dissolved oxygen, tides, salinity, current 6. Other terrestrial factors – wind, fire Ecologists study environmental interactions at these different levels Levels of organization (lowest to highest) Species/ Organism - individual living thing Population – group of organisms of same species in same area Community – many populations or organisms living close enough for interaction Ecosystem – include biotic & abiotic components in an environment Biome – group of ecosystems with same climate Biosphere – all of Earth What could an ecologist study at each level? Biosphere Biome Ecosystem Community Individual Population What levels of organization include nonliving things? Energy, Producers, and Consumers Where does the energy for life processes come from? Producers Without a constant input of energy, living systems cannot function. Sunlight is the main energy source for life on Earth. In a few ecosystems, some organisms obtain energy from a source other than sunlight. Some types of organisms rely on the energy stored in inorganic chemical compounds. Only plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food. These organisms are called autotrophs. Because they make their own food, autotrophs are primary producers. The best-known autotrophs harness solar energy through a process known as photosynthesis. During photosynthesis, these autotrophs use light energy to convert carbon dioxide and water into oxygen and energy-rich carbohydrates. Photosynthesis is responsible for adding oxygen to— and removing carbon dioxide from—Earth's atmosphere. Life without Light Some autotrophs can produce food in the absence of light. When organisms use chemical energy to produce carbohydrates, the process is called chemosynthesis. Consumers Many organisms cannot harness energy directly from the physical environment. Organisms that rely on other organisms for their energy and food supply are called heterotrophs. Heterotrophs are also called consumers. There are many different types consumers. • Herbivores eat plant Leaves, roots, seeds, or fruits • Carnivores kill and Eat other animals • Omnivores eat both plants and animals. • Detritivores feed on detritus, small pieces of dead and decaying plant/animal remains Decomposers, like bacteria and fungi, break down organic matter. (produce detritus) Scavengers consume the carcasses of other animals that have been killed gy predators or have died of other causes How does energy flow through living systems? Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers). Food Chain A food chain is a series of steps in which organisms transfer energy by eating and being eaten. Food Web Ecologists describe a feeding relationship in an ecosystem that forms a network of complex interactions as a food web. A food web links all the food chains in an ecosystem together. Trophic Levels Each step in a food chain or food web is called a trophic level. Producers make up the first trophic level. Consumers make up the second, third, or higher trophic levels. Each consumer depends on the trophic level below it for energy. Ecological Pyramids A diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. The amount of energy/matter in an ecosystem can be represented by an ecological pyramid. Three types includes: Energy pyramid Biomass pyramid Pyramids of numbers Ecological Pyramids Energy Pyramid: Shows the relative amount of energy available at each trophic level. Only part of the energy that is stored in one trophic level is passed on to the next level. Copyright Pearson Prentice Hall Biomass = total amount of living tissue in a trophic level WHAT DO YOU NOTICE AT EACH TROPHIC LEVEL? Copyright Pearson Prentice Hall Ecological Pyramids WHAT DO YOU NOTICE AT EACH TROPHIC LEVEL? Copyright Pearson Prentice Hall Cycles of Matter How does matter move among the living and nonliving parts of an ecosystem? Recycling in the Biosphere Energy and matter move through the biosphere very differently. Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Biogeochemical Cycles The Water Cycle Water continuously moves between the oceans, the atmosphere, and land – sometimes out of living organisms and sometimes inside them The Carbon Cycle The Nitrogen Cycle The Phosphorus Cycle Nutrient Limitation Limiting nutrient – nutrient whose supply limits productivity How Populations Grow Describing Populations 4 important characteristics of a population are: 1. population density – number of individuals per unit area 2. geographic distribution/range – area inhabited by a population 3. growth rate – determines if the population is icreasing, decreasing, or staying the same 4. age structure – the number of males/females of each age a population contains Population Growth Three factors can affect population Growth: 1. the number of births 2. the number of deaths 3. the number of individuals that enter or leave the population A population can grow when its birthrate is greater than its death rate. Population Growth - Immigration, the movement of individuals into an area - Emigration, the movement of individuals out of an area Exponential Growth Under ideal conditions with unlimited resources, a population will grow exponentially. Exponential growth occurs when the individuals in a population reproduce at a constant rate. The population becomes larger and larger until it approaches an infinitely large size. Logistic Growth As resources become less available, the growth of a population slows or stops. Logistic growth occurs when a population's growth slows or stops following a period of exponential growth. Carrying capacity = largest # of individuals in a population that an environment can support Human Population Growth Answer the following based upon the graph: 1.What type of growth is the human population in? 2. It is believed that the carrying capacity of humans is between 8 and 10 billion. When could these numbers be reached according to the graph? 3.What factors have contributed to the world’s overall population growth in the last 150 years? 4.Hypothesize what will happen when the human population exceeds Earth’s carrying capacity. Limits to Growth The primary productivity of an ecosystem can be reduced when there is a small t supply of a particular nutrient – called limiting nutrients A limiting nutrient is an example of a more general ecological concept: a limiting factor. In the context of populations, a limiting factor is a factor that causes population growth to decrease and reach carrying capacity. Density Dependent Factors A limiting factor that depends on population size is called a density-dependent limiting factor. Density-dependent limiting factors include: • competition • predation • parasitism • disease Density Dependent Factors Density-dependent factors operate only when the population density reaches a certain level. These factors operate most strongly when a population is large and dense. They do not affect small, scattered populations as greatly. Density Dependent Factors Competition occurs… • When populations become crowded, organisms compete for food, water space, sunlight and other essentials. • among members of the same species • between members of different species. –This type of competition can lead to evolutionary change. Density Dependent Factors - Populations in nature are often controlled by predation. - The regulation of a population by predation takes place within a predator-prey relationship, a known mechanisms of population control. Wolf and Moose Populations Moose Wolves Density Dependent Factors Parasitism Parasitism and Disease - Parasites and disease causing agents (bacteria/virus) feed at the expense of their hosts. - Weakens, causes disease, and sometimes death in host Density Dependent Factors Stress from Overcrowding - Some species fight among themselves if overcrowded. - Too much fighting = high stress levels → weakens body’s ability to resist disease Density Independent Factors Density-independent limiting factors affect all populations regardless of the population size. Examples of density-independent limiting factors include: • unusual weather • natural disasters • seasonal cycles • certain human activities—such as damming rivers , clear-cutting forests, introducing species Cane Toads 1. What are some benefits for species that are introduced into a new ecosystem? 2. What are some things that can go wrong when an organism is introduced into a new ecosystem? 3. How are organisms introduced into a new ecosystem? Questions 1. Population size is based upon density dependent and independent factors. Briefly explain the difference between the two. 2. What are examples of density dependent factors? 3. What are examples of density independent factors? What shapes an ecosystem? Biotic factors – biological influences on organisms in an ecosystem examples include… Abiotic factors – physical, nonliving, factors that shape ecosystems examples include… Climate includes precipitation, temperature, and humidity In any ecosystem, removing biotic elements can dramatically affect the ecosystem’s abiotic conditions. for example: if you remove trees from the forest → no more shade for soil, can’t contribute organic matter to soil, can’t return water to the atmosphere through evaporation or transpiration Think of other examples of how removing biotic elements from an ecosystem could affect the abiotic elements. What shapes an ecosystem? Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives. The area where an organism lives is called its HABITAT. This is like an organisms address. The Niche A niche is the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions. If a habitat is like an organisms address, a niche is like its occupation. It includes the type of food an organism eats, how it obtains the food, and which other species use the organism as food Cape May Warbler Community Interactions Community interactions can affect an ecosystem. Types of interactions include… Competition Predation Symbiosis Competition Organisms attempt to use an ecological resource in the same place at the same time and competition occurs resources include… food, shelter, water Competitive exclusion principle states that no two species can occupy the same niche in the same habitat at the same time. Predation An interaction in which one organism captures and feeds on another organism Predators can be passive or active What does it mean to be a passive predator? Active predator? Symbiosis Any relation in which two species live closely together 3 types include: Mutualism Commensalism Parasitism Symbiosis Mutualism – both species benefit from the relationship ex: flowers and insects rhinos and cleaning birds Symbiosis Commensalism – one member of the association benefits and the other is neither helped nor harmed ex: barnacles and whales orchids on a tree Symbiosis Parasitism – one organism lives on or inside another organism and harms it ex: caterpillar and parasitic wasp, tapeworms and mammals, fleas/ticks/lice Type of Species relationship harmed Commensalism Species benefits Species neutral Parasitism Mutualism = 1 species Can you think of any other symbiotic relationships? Give 5 examples and tell what type of symbiotic relationship is occurring. Symbiotic Videos Clip 1: Shark/Turtle Clip 2: Shark/Jack, Shark/Mackerel, Shark/Shark Suckerfish, Hammerhead Shark/Barberfish Clip 3: Shark/Fishermen Symbiotic Relationships Symbiotic Relationships Ecological Succession A series of predictable changes that occur in a community over time What types of human activities can disturb an ecosystem and cause succession? There are two types: Primary Secondary Primary Succession - Occurs in an area with no remnants of an older community (ex: after volcanic eruption) 1. First species are pioneer species (lichens) 2. Lichens break the rock down adding organic material to form soil 3. When the soil is rich grasses colonize the area. Then bushes and trees. 4. As most plants colonize the area more animals do also. Secondary Succession -occurs faster than primary succession -Soil has survived after a disturbance (wildfire, hurricane) -Surviving vegetation regrows rapidly