Ecology Pearland High School • 2008

What is Ecology Ecology is the scientific study of interactions among organisms and between organisms and their environment.

Biotic & Abiotic Biotic – all living organisms (plants & animals). Abiotic – all nonliving things (rocks, gases, minerals). Biosphere – where all living and non living things are found (land, water, air). Abiotic Biotic

Biosphere Different populations make up the biosphere. Population – groups of organisms of one species that live in the same place. Populations use the same: food, water, mates, territory. Different populations that interact make up Communities. Examples: fish and alligators share the same territory (habitat) and interact with one another (predator/prey). All the interactions make up the Ecosystem. Biomass is the total amount of living tissue in a given area.

Levels of Organization Biome

Levels of Organization Biosphere Biome Ecosystem Community Population Individual

Levels of Organization Biosphere – part of Earth that contains life. Biome – group of ecosystems that have similar climate and dominant communities. Ecosystem – collection of all the organisms that live in a particular place along with all abiotic factors (nonliving). Community – different populations that live together in the same area. Population – groups of individuals that live in same area. Individual – one member of a species living in the population.

Levels of Organization Air, water, land Rainforest, desert, tundra Cactus, snakes, rocks, sand Deer, rabbits, owls Frogs in a lake One frog

Niche The status of an organism within its environment and community (affecting its survival as a species). What an organism does to stay alive. Ex. Bacteria decomposes dead organic material.

Autotrophs Organisms that capture energy from sunlight or chemicals and use that energy to produce food are called autotrophs or producers. They use light energy to convert carbon dioxide and water into oxygen and carbohydrates during a process called photosynthesis. Several types of bacteria do this process. Green Slime

Two Main Forms of Energy for Autotrophs Sunlight The main source of energy for life on earth: photosynthesis. Chemical Some organisms such as bacteria, rely on the energy stored in inorganic compounds: chemosynthesis.

Heterotrophs Organisms that do not get energy directly from the physical environment, but from other organisms are called heterotrophs or consumers. Heterotrophs are the consumers of the food chain. They can't produce their own food using energy from the sun like an autotroph can. Heterotrophs eat plants or other animals to get energy for life.

Types of Heterotrophs Herbivores - obtain energy by eating only plants ex: cows, caterpillars, deer Carnivores - obtain energy by eating animals ex: snakes, dogs, owls Omnivores - obtain energy by eating both plants and animals ex: humans, bears, crows Detritivore - obtain energy by feeding on plant and animal remains ex: mites, earthworm, snails, crabs Decomposers - breakdown organic matter ex: bacteria, fungi

Energy Transfer When an organism eats another organism, energy is transferred. Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers).

How Does Energy Flow Through an Ecosystem? Energy flows through an ecosystem in one direction, Sun or chemicals Autotrophs Heterotrophs

    Trophic Levels Decomposers 5th  Quarternary 4th  Tertiary Consume r s 5th  Quarternary 4th  Tertiary 3rd  Secondary 2nd  Primary 1st  Producers    

Trophic Levels 4th 3rd 2nd 1st Decomposers 4th  Secondary Carnivores 3rd  Primary Carnivores 2nd  Herbivores 1st  Producers 1st 2nd 3rd 4th Decomposers

Energy Cycles Energy flows through an ecosystem from producer to consumer and is eventually recycled by decomposers. Each living thing is dependent on the other living things in the community. Energy constantly cycles through the ecosystem. Example: rabbit is born, rabbit lives a happy life, rabbit gets run over by car, vulture and coyotes eat remains and gain energy from food, bacteria decompose the rest of the living matter for energy.

Models of Energy Cycles Food Chain – Most simple model which shows how energy flows from one organism to another. Only goes in one direction. Ex.: rabbit coyote bacteria Food Web – network of interconnected food chains. Shows more than one path energy flows through environment. Trophic Levels – each organism represents a step in which there is a 10% gain and the rest of the energy is lost to heat. Ecological Pyramid – puts populations by numbers and energy level starting with producers at the bottom of the pyramid.

Food Chain Energy is stored by producers can be passed through an ecosystem along a food chain. A food chain is a series of steps which organisms transfer energy by eating and being eaten. A food web links all the food chains in an ecosystem together.

Steps in a Food Chain Each step in a food chain or web is called a trophic level. Producers make up the first trophic level and consumers make up the higher levels. An ecological pyramid shows the relative amounts of energy or matter contained within each trophic level in a food chain or web.

Food Chain

Food Web A food web is used to represent the feeding relationships among the various organisms in an ecosystem that form a network of complex interactions.

Ecological Pyramids At each level energy is lost in the form of heat. The greatest amount of available energy is found at the bottom level of the pyramid. Producers are the living things that have the most energy available to them.

Types of Ecological Pyramids Energy pyramid: only about 10% of the energy is transferred from on trophic level to the next, the rest is lost as heat. Biomass pyramid: represents the amount of potential food available for each trophic level in an ecosystem. Pyramid of numbers: shows the relative number of individual organisms at each trophic level.

Energy Pyramid Energy flows through ecosystems from producers to the various levels of consumers. Each time an organism eats another, not all the energy is transferred.

Energy of the Producers Energy Pyramid Only about 10% of the energy of a producer is transferred to the consumer that eats it. Therefore, there is a progressive loss of energy at each level of a food chain. We can represent the amount of energy at each level as a part of a pyramid. Energy of the Producers Primary Consumer Other Consumers

Biomass Pyramid It is possible to estimate the mass of all the organisms living in a given area or ecosystem. This estimation is known as the biomass. If the mass of the producers and each type of consumer is recorded, a pyramid can be constructed showing that the biomass of the producers is generally far greater than that of the consumers. Biomass of Producers Primary Consumers Secondary Consumers Tertiary Consumers

Pyramid of Numbers A pyramid of numbers is a graphical representation of the numbers of individuals in each population in a food chain. Often it is drawn from the autotrophic level up. A pyramid of numbers can be used to examine how the population of a certain species affects another. In a Lake Community 10 180 500 10000 In a Tree Community 3 20 76 1

Inter-Dependence Symbiosis – living together. Types of Symbiosis One organism depending on another for its survival. This is a relationship all living things share. Types of Symbiosis Mutualism – both organisms benefit; ex. plants giving off O2 for animals and animals giving off CO2 for plants to use. Parasitism – one organism benefits and the other is harmed; ex. tapeworm living in a person’s intestine. Commensalism – one organism benefits and the other is not affected; ex. birds nesting in trees.

Environmental Homeostasis Life is sustained by a balance of environmental factors and by maintaining a balance of nutrients that are necessary for living organisms. These are water, carbon, and nitrogen. Each of these cycles through the environment such that the balance can be maintained.

Water Cycle How the Environment Maintains Homeostasis

Carbon Cycle How the Environment Maintains Homeostasis

Nitrogen Cycle How the Environment Maintains Homeostasis

Population Dynamics Population growth is limited by certain factors: Space available Food Competition for resources between different species Number of mates Natural disaster Disease Temperature Each ecosystem has a carrying capacity. This means the area can only support a certain number of each species due to the limiting factors for populations.

Human Populations Factors affecting Human Population growth: Birth rate and Death rate Birth rate – Death rate = population growth rate Fertility When fertility is high populations increase Population Age Very young / immature pre-reproductive Reproductive mature ( only ones that can increase population ) Post-reproductive / very old Mobility Immigration – movement into a population Emigration – movement out of a population

Ecological Homeostasis Limiting factors are biotic and abiotic conditions that maintain balance in every community and keep populations from growing out of control. Availability of food Temperature Shelter Availability of mates The ways communities grow into new niches is called Succession. Primary Succession – colonization of new environments (ex. islands). Secondary Succession – usually happens after natural disasters or other major changes to the environment.

Ecological Succession

The Major Biomes Tundra Taiga Temperate Deciduous Forest Temperate Grassland Desert Savanna Tropical Rain Forest Freshwater and Saltwater Aquatic

Terrestrial Biomes Biomes are very large terrestrial ecosystems that contain a number of smaller but related ecosystems within them. A certain biome may exist in more than one location on Earth, but similar biomes have similar climates and tend to have inhabitants with similar adaptations.

Tundra Biome: deciduous forest A vast plain covered by low trees and shrubs growing in a thin layer of soil over permafrost.

A forest characterized by evergreen trees such as spruce and fir. Taiga Biome: deciduous forest A forest characterized by evergreen trees such as spruce and fir.

Temperate Deciduous Forest Biome: deciduous forest A forest characterized by trees that shed their leaves in the fall.

Desert Biome: grassland An area that receives ten inches, or less, of precipitation per year.

Temperate Grasslands Biome: grassland Vast area covered with grasses of various heights depending on the amount of rainfall. The more the rainfall the tall the grasses.

Savanna Biome: grassland Subtropical or tropical grassland with tall grasses, scattered trees, and shrubs.

Tropical Rain Forest Biome: grassland Biome dominated by broad leafed evergreen trees, is near the equator, and has in excess of 300 inches of rain per year.

Just as populations contain interacting members of a single species, communities contain interacting populations of many species. Plants and animals as well as abiotic and biotic factors are all part of any ecosystem. Carnivores…symbiotic relationships