Ecology 4.1 – 4.2 Eric Molina

Species, Communities, and Ecosystems Species – A group of similar organisms that can breed and produce fertile offspring Common gene pool Populations can become isolated Isolated species might find itself evolving in a different way compared with the rest of the population

Autotrophs & Heterotrophs Autotrophs – capable of making their own organic molecules as a source of food Process involves photosynthesis Examples of autotrophs Cyanobacteria Algae Grass / Trees

Autotrophs Obtain inorganic nutrients from abiotic (nonliving) environment

Autotrophs & Heterotrophs Heterotrophs – cannot make their own food from inorganic matter and must obtain organic molecules from other organisms Get chemical energy from autotrophs or other heterotrophs Examples: Zooplankton Fish Sheep Insects

Consumers Obtain chemical energy by feeding on the producers or other consumers (heterotrophs)

Detrivores Eat non-living organic matter (internal digestion) Like dead leaves, feces, and dead animals (carcasses) Earthworms, woodlice, and dung beetle Many bottom feeders in rivers, lakes, and oceans are detrivores

Saprotrophs Live on or in non living organic matter They secrete digestive enzymes and absorb the products of digestion (external digestion) They play an important role in the decay of dead organic materials Fungi and bacteria

Communities Is formed by populations of different species living together and interacting with each other.

Ecosystems Abiotic – non-living components of the environment. Water, Air, rocks, pH, Light, relative humidity, and temperature Biotic – Living components of the environment A community forms an ecosystem by its interactions with the abiotic environment

Nutrient Cycling There is not enough minerals to meet the needs of all the organisms in the biosphere As a result ecosystems must recycle the carbon, nitrogen, and other elements and compounds necessary for life to exist. Decomposers – eat waste and remains of dead organisms Saprotrophs and detritivores

Nutrient Cycling Nitrogen (N) is found as amino acid in all living things Although 80 % of Earth’s atmosphere is Nitrogen gas; most organisms can only use Ammonium (NH₄⁺) and Nitric Acid (NO₃⁻) Decomposers use digestive enzymes and convert the organic matter into a more useable form for themselves and for other organisms proteins from a dead organism are broken down into ammonia (NH₃) and in turn ammonia can have its nitrogen converted into useful nitrates (NO₃) by bacteria.

Nutrient Cycling Decomposers recycle nutrients so that they are available to other organisms and are not locked inside the bodies or waste products of the ecosystem Ecosystems have the potential to be sustainable over long periods of time

Nutrient Cycling Nitrogen Fixation Bacteria are able to transform nitrogen into useful forms Such as nitrates Usable nitrates are absorbed by plants and then eaten by consumers Nitrogen is return to the ecosystem in urea and feces

Photosynthetic Producers Plants that convert light energy from sunlight to the chemical energy of organic compounds. Most ecosystems rely on a supply of energy from sunlight.

Energy Flow There are ecosystems that exist in total darkness. Deep ocean water Deep underground

Photosynthesis Photosynthetic organisms take simple organic compounds, CO₂, and convert it into energy-rich sugar, C₆H₁₂O₆. The addition of minerals allows the producers to synthesize complex molecules such as cellulose, proteins, and lipids.

The Path of Energy and Chemicals in a Ecosystem Every organism requires energy to carry out life’s process: Growing Moving Reproducing

The Path of Energy As living things use chemical energy, they release thermal energy (Heat) to the surroundings Living (most) organisms cannot convert heat to other forms of energy

The Path of Energy Energy is not recycled within an ecosystem, but flows through it and out. Producers must continue to receive energy so they can transfer that energy; if not the ecosystem could not survive.

Food Chains Trophic Level – A feeding level in an ecosystem Food Chain – the pathway of food transfer from one trophic level to another Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels

Pyramid of Energy A pyramids of energy is used to show how much and how fast energy flows from one trophic level to the next in a community. The units used are energy per unit area per unit of time. Kilojoules per square meters per year (kjm⁻²yr⁻¹)

Pyramid of Energy Know This : Not This

Food Webs In an ecosystem the feeding relationship is usually more complicated than a simple food chain Because of the variety of species; animals and plants Food Web – the pattern of feeding by interconnected and branching food chains