ECOLOGY – What is it? • The scientific study of interactions between organisms and their environments, focusing on energy transfer • It is a science of relationships.
The environment is made up of two factors: • Biotic factors- all living organisms inhabiting the Earth • Abiotic factors- nonliving parts of the environment (i.e. temperature, soil, light, moisture, air currents)
Levels of Organization in Ecology • Organism →Species Population → Community → Ecosystem → Biome → Biosphere
Levels of Organization • Species - Group of organisms so similar to one another that they can breed and produce fertile offspring. • Ex - elephant • Population - Groups of individuals that belong to the same species and live in the same area. • Ex – herd of elephants • Communities -Assemblages of different populations that live together in a defined area. • Ex – elephants, zebras, water buffalos, warthogs, hippos
Levels of Organization • Ecosystem – Collection of all living and nonliving things in a determined place • Ex – mud hole, grass, warm temperature, elephants, zebras, giraffes, insects, sun • Biome - Group of ecosystems that have the same climate and similar dominant communities. • Ex – Tropical Savanna (Kenya, Zaire, Tanzania-Africa) • Biosphere – Part of the planet in which all life exists, including land, water, and air (all ecosystems combined) • It extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean.
Habitat vs. Niche… • Niche - the role a species plays in a community (job) • Habitat- the place in which an organism lives out its life (address) • A niche is determined by the tolerance limitations of an organism, or a limiting factor.
Consumers • Herbivores - eat plants • Carnivores – eat animals • Omnivores – eat both plants and animals • Decomposer – break down dead organic matter chemically (bacteria) • Detritivores – feedson plant and animal remains (crab, earthworm)
Decomposers vs. Detritivores • Decomposers • Bacteria and fungus • Detritivores: • maggots • dung beetles • earth worms • sow bugs Without them there would be a lot of dead bodies lying around!
Leeches and maggots are now classified as FDA-approved medical devices — the first live animals to earn that distinction.
Interesting Science! These maggots are cleaning/removing the dead tissue from this wound. If the dead tissue is not removed, the wound will not heal correctly…may end up with a big hole in their heel.
Interesting Science! All of the yellow tissue is necrotic (dead) tissue. The pink tissue is granulation (newly formed) tissue. The dead tissue must be removed for proper wound care or else the tissue will not grow and fill in the hole
Food Chain vs. Food Web • Food Chains shows how matter and energy move through an ecosystem • follow just one path as animals find food. 2.Food Websshows all possible feeding relationships in a community at each trophic level I. follow all possible energy paths
What Do Food Chains and Food Webs Demonstrate? • Both food chains and food webs show the flow of energy in an ecosystem. Energy flows from the leaf to the mouse Energy flows from the snake to the hawk
Trophic Levels • Corresponds to the different levels or steps in the food chain. • Represent a feeding position in the transfer of energy and matter in an ecosystem. • Green plants: first trophic level, the producers. • Herbivores: second trophic level • Carnivores: third and even the fourth trophic levels. Food Chains ALWAYS begin with plants (producers)!!
Trophic Levels Tertiary consumers- top carnivores Secondary consumers-small carnivores Primary consumers- Herbivores Producers- Autotrophs
Matter vs. Energy • Matter – Has mass, takes up space, is usually a “thing” • Energy – Not like matter, does not have mass, does not take up space, energy moves matter • Forms of energy: light, heat, sound, motion, and electricity
How Much Energy is Passed On? • Only 10% is passed on to the next trophic level • The other 90% is lost/given off as heat 100% 10% 1% .1%
Food Chains: Matter and Energy • As you move up a food chain, the matter and energy decreases. • Energy is transferred upwards but is diminished with each transfer. .1% Energy 1% Energy 10% Energy 100% Energy Pyramids are larger at the bottom…more matter and energy are at the bottom of the pyramid!
Ecological Pyramids • Ecological Pyramid- diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.
Two Types of Ecological Pyramids • Pyramid of Biomass – Represents the biomass at each trophic level • Pyramid of Numbers – Represents the number of organisms at each trophic level
Ecological Pyramid: Pyramid of Biomass • Biomass – total amount of living tissue within a trophic level • Usually expressed in grams per unit area. • As you move up a food chain, both available energy and biomass (matter) decrease. • Energy is transferred upwards but is diminished with each transfer.
Pyramid of Numbers As you go further down a food chain, the numbers of organisms decrease because there is less energy available (like in this meadow)!
Other Pyramid of Numbers If you have a large producer (such as a tree in a forest), the pyramid of numbers may look diamond in shape. A large tree supports a lot of organisms.
Population Changes in Food Chains • What would happen to this bird if the population of caterpillars decreases?
Population Changes in Food Chains • What would happen to this bird if the population of caterpillars decreases? • The bird population would decrease also because he would have less food.
Population Changes in Food Chains • What would happen to the bee population if the flower population exploded?
Population Changes in Food Chains • What would happen to the bee population if the flower population exploded? • The bee population would also increase.
Population Changes in Food Chains • If the snake population decreases, what would happen to the other organisms in the food chain?
Population Changes in Food Chains • If the snake population decreases: • The hawk population decreases also (less food) • The frog population increases (less predators eating them) • More frogs eating the grasshoppers, so less grasshoppers
Carrying Capacity • Number of species that can be supported by an ecosystem. (Average growth rate = zero) • Population Growth is Represented With an S-Curve
Population Growth • Exponential - individuals in a population reproduce at a constant rate (Ideally happens IF there are unlimited resources) (J-curve) • Logistic – The growth of a population slows or stops as resources become less available (S-curve)
. 3 Factors that affect population size: • 1. # of births • Populations will grow if birthrate > death rate • Populations will shrink if birthrate < death rate • Populations will stay the same birthrate = death rate • 2. # of deaths • 3. # of individuals that enter or leave a population • Immigration = movement of individuals INTO an area (growth) • Emigration = movement of individuals OUT of an area (shrink)
Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.
Limiting Factors: Limit Population Growth • Limiting factors: • a. Density independent: factors that affect all members of the population equally if population is dense or not. • Natural disasters: floods, earthquakes, wildfires, tornadoes, mudslides, pollution, habitat destruction • b. Density dependent: factors that affect crowed populations • EX: competition, predation, crowding and stress, parasitism, and disease
Competition • Competition – A rivalry between organisms for the same resources; The fitness of one of the organisms is lowered by the presence of another. • Limited supply of at least one resource used by both organisms is required • Example:Animals compete for food, mating, or territory and plants can compete for water, food, minerals, sunlight.
Predators • Organism that hunts and kills other organisms • Can be carnivores or omnivores
The Importance of Predators • We need them to control populations • Without predators, certain species like mice would crowd out other species and would also destroy their habitat. • They also get rid of weak, crippled, stupid, stunted, and diseased organisms (survival of the fittest)
Large Predators • The number of large predators is decreasing.
Wild Rabbits in Australia • Early 1900's, wild rabbits were taken from England to Australia to be used for hunting. • Since then, rabbits have multiplied exponentially and have severely affected the ecosystem where they live. • Damages include: • Loss of vegetation from rabbit grazing – threatens the survival of native animals that rely on plants for food and shelter • Wild rabbits compete with livestock for available pasture and kill young trees & shrubs. • The holes they dig contribute to soil erosion by removing vegetation and disturbing soil.
Symbiotic Relationships: • Interactions between two or more organisms; Two different species start a relationship (interact) in order to ensure survival
Predation • The capturing of prey as a means of maintaining life • One organism benefits • One organism is killed
Parasitism A tomato hornworm is covered with cocoons of pupating braconid wasps One organism (the parasite) benefits and the other (the host) is harmed, but is still alive Because the parasite needs the host to remain alive, it is typically advantageous for the parasite NOT to kill its host
Mutualism • Relationship that benefits both species.
Examples of Mutualism • Pollination • Seed Dispersal • Anemones http://player.discoveryeducation.com/index.cfm?guidAssetId=5A1EACD2-3483-41F0-86B1-47B8300065E0&blnFromSearch=1&productcode=US Hippo and fish
Commensalism • One species benefits and the second species is unaffected Barnacles and Cattle Egrets • Barnacles and Algae
Interactions Summary Is Killed Still Alive “It’s Mutual.”