Ecology & EcosystemsObjectives: Contrast exponential and logistical growth. Differentiate r and k strategies of reproduction. Summarize the Hardy-Weinberg principal. Distinguish and ecosystem from a community. Describe the process of succession. Distinguish between producers and consumers. Compare food webs and food chains.

EcologyEcology is the scientific study of interactions between life forms and their environment.Shenandoah Mountains, VA

The Dead and AliveBiotic living organisms in an ecosystem.Abiotic non-living matter in an ecosystem. Examples: air, and rocks.

The NicheThe area in which an organism lives including all the living and nonliving matter it needs to survive.Shenandoah Mountains, VA

Population DensityPopulation density is the number of organisms per unit area.

Population Growth RatesThree factors affect population size:Number of birthsNumber of deathsNumber that enter or leave a population

Entering a PopulationImmigration movement into a population that increases population size.

Leaving a PopulationEmigration The movement of individuals away from the population that causes a decrease in population size. (E for exiting, I for increases.)

Exponential GrowthOccurs under ideal conditions with unlimited resources the population will grow exponentially.The graph to the left shows a population growing by and unlimited number of births, and unlimited numbers of organisms entering the population.

Logistic GrowthUnlimited resources are simply not available, so growth is limited.The graph to the left shows a population that has reached a carrying capacity and the population growth rate has slowed due to limited food, space, or water resources.

Carrying Capacity The number of individual species an environment can support given the available resources such as food or space.

Growth StrategiesThere are two ways animals reproduce to ensure their young survive to adulthood:R-Strategy Reproduce large numbers and only a few survive to adulthood. Ex. Sea Turtles, and Roaches.K-Strategy Reproduce small numbers and young will usually survive to adulthood. Ex. Humans, and Whales.

Density-Dependant FactorsANY factor that depends on population size.Density-Dependant factors are caused by - As population increases, so does:CompetitionPredationParasitism and Disease

Density-Independent FactorsEffect all populations regardless of size.Density-Independent factors may cause a large drop in population size.They are caused by:Unusual Weather Natural DisastersSeasonal CyclesHuman Activities like deforestation.

Examples of Factors that Limit Population Growth:

Organization One organism is a species.Groups of species are populations.Groups of different populations of animals are communities.Groups of different populations of animals and their nonliving environment is an ecosystem.Groups of ecosystems make up a biome.

3 Types of Community InteractionsCompetition Two organisms fighting for one resource.Predation Hunter and Hunted.Symbiosis (has 3 different types)Mutualism both benefit Commensalism one benefits other is not affected.Parasitism one benefits, the other is negatively affected.

Types of SuccessionPrimary Succession: Pioneer species are the first to colonize an area with available space.Secondary Succession: Organisms growing in an area where growth has been naturally or unnaturally interrupted.Example: A forest burns down and small trees and grasses are the first to grow out

Energy Flow in an EcosystemThere are two types of organisms who make their own food:Autotrophs Use sunlight to produce chemical energy (sugars).Chemotrophs - Some organisms rely on the energy stored in inorganic chemical compounds from Earths crust. Hydrothermal Vent Communities at the bottom of the Oceans contain Chemotrophs.

Energy From the SunPhotosynthesis The use of light energy to power chemical reactions that produce energy.On land plants are the main autotrophs or producers.In the sea the phytoplankton are the main autotrophs or producers.

ConsumersConsumers are Heterotrophs They must eat to obtain energy.There are five types of consumers:Herbivores - eats plants onlyCarnivores eats other organismsOmnivores eats plants or animals.Decomposers - feed off of organic matterDetritivores feed off of dead organic matter called detritus. (ex. Earth worms)

Feeding RelationshipsEnergy flows through an ecosystem in one direction:Sun autotrophs heterotrophs.Energy stored by producers is passed up the food chain.

Food WebsFood webs connect all food chains.

What kind of food web is this?

Trophic LevelsEach step in a food chain is called a trophic level.NOTE: Energy is lost as it travels up the food chain in the form of body heat and other bodily functions from living a normal life. 1000 pounds of phytoplankton 100 pounds of zooplankton1 pound of small fish0.01 pound of shark

The Water Cycle

The Carbon Cycle

How Nitrogen is:Released in an ecosystem:Nitrogen Fixing (Nitrification) Bacteria in the soils leading toUptake by primary producers.Also, atmospheric Nitrogen Fixation by lightning. Absorbed into an ecosystem:Deposition, Excretion of feces.Denitrification by soil bacteria.Erosion.

The Phosphorus CyclePhosphorus is taken up by plants, which are eaten by organisms, and when they die the phosphorus returns to the sediments.Phosphorus does not enter the atmosphere.

It remains mostly in soils, rocks, and ocean sediments.

Nutrient LimitationPrimary Productivity - the rate in which organisms create organic matter.

An ecosystem can be limited by a single nutrient if it is in short supply.

When nutrient levels are present in excess blooms of growth occur.

(Fertilizing a lawn is giving the grass extra phosphorous and nitrogen for faster growth.)

BiomesEach biome has its own unique climate and unique organisms.There are 10 biomes.

10 BiomesTropical RainforestDry Tropical ForestTropical SavannaDesertTemperate GrasslandTemperate Woodland and ShrublandTemperate ForestNW Coniferous ForestBoreal ForestTundra

Aquatic EcosystemsFreshwater habitats are limited in space.Ponds and lakes have 3 habitats in which organism live:Littoral zone shallow zone near the shore.Limnetic zone the area that is farther away from shore but close to the surface.Profundal zone deep-water zone below the limits of light penetration.An estuary is a body of water that is half salt water, half fresh water. Ex. Mouth of a river.Plankton small invertebrate animals.

Negative Environmental EffectsAcid Rain - Acidic precipitation.Ozone Hole - Being destroyed by CFCs, or chlorofluorocarbons. High in the atmosphere the suns ultraviolet radiation breaks up the bonds of the CFC molecule and the resulting molecules eat up ozone.Global Warming - A natural process.Greenhouse Effect - Traps excessive heat in the atmosphere by not letting it reflect back into space and is speeding up global warming.

Effects on an EcosystemBiological Magnification - pollutants magnify as they work up the food chain. Example: 5 small fish contain one DDT molecule each and are eaten by a larger fish. The larger fish now contains 5 DDT molecules.Five larger fish are eaten by a hawk. The hawk now contains 25 molecules of DDT.

Biological Magnification

The Human PopulationThe current human world-wide population is around 6 billion people.About 180 people are added each minute.Technology helps people not only live longer, but it helps populations grow faster.The United Nations predicts the world population will stabilize around 9.7 billion people, on or around the year 2050.