ecology

EcologySarah Jones

hdw.eweb4.com

Environment

The environment of an organism is its surroundings, both living and non-living.

EcosystemsAn ecosystem is a part of the environment containing living organisms interacting with each other and the non-living parts of the environment.

EcologyEcology is the study of relationships living organisms have with each other and their environment.

Ecosystems

Aquatic Ecosystems

Saltwater - open seas, estuaries and saltwater lakes.Approximately 65% of the Earth's surface is covered by oceans. Tides, currents, waves and wind continuously move the water in the surface layers.

Freshwater - includes still water such as lakes and ponds, swamps, and moving water such as springs creeks and rivers.

Terrestrial Ecosystems

Terrestrial environments vary as a result of topography, climate, availability of water, and human activity.

Examples: rainforest, open forests, mountain tops, deserts, grasslands, farms and cities.

PopulationA group of living organisms of the same kind living in the same place at the same time.

CommunityOrganisms living together in a particular place.

HabitatThe habitat of an organism is the place where it lives. These can vary in size e.g. desert, under tree bark, within the digestive system of another organism.

Ecosystems will fail if they do not remain in balance.

No community can carry more organisms than its food, water and shelter can accommodate.

Food and territory are often balanced by natural phenomena such as fire, disease, and the number of predators.

Abiotic Factors of Ecosystems

LightWindRainfallTemperature (daily and seasonal)Topography (altitude and depth)Tides, currents and wavesWater (salinity, pH and availability)Substrate (surface on which an organism grows or is attached)Space and shelterOxygen

Biotic Factors of Ecosystems

Availability of foodNumber of competitorsAvailability of matesNumber of predatorsDisease causing organisms

Limiting factors - anything that makes it difficult for a species to live and grow, or reproduce in its environment.

Food Chains and Food Webs

Organisms have roles in ecosystems:

Producers - organisms that make their own food using the energy of sunlight - plants.

Consumers - obtain their food by consuming other creatures - if they consume a producer then they are primary consumers or herbivores - if they consume herbivores they are secondary consumers or carnivores.

If they consume carnivores they are tertiary consumers or carnivores. Some species eat both producers and other consumers and they are called omnivores. Some creatures eat dead producers or consumers and are called detritivores.

Bacteria and fungi that break down dead organic material. Decomposers have an important role in ecosystems - they absorb nutrients from dead organisms or waste materials and return organic matter to the soil.

Decomposers

Food chains are simple ways of representing feeding relationships among organisms.

Grass > insect > spider > bird

Food webs show the feeding relationship of all organisms in a particular location (food web = many food chains intertwined together).

Energy

PhotosynthesisPhotosynthesis is the process by which plant cells capture energy from sunlight and use it to combine carbon dioxide and water to make sugars and oxygen.

Six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen.

All living things ultimately depend on this process - photosynthesis.Organisms that consume the plants gain nutrients and energy, animals that eat the plant-eaters gain energy from them, therefore the energy is passed on.

Respiration

Respiration is the process by which cells obtain energy.Organic molecules (particularly sugars) are broken down to produce carbon dioxide and water, and energy is released.

Biomass and Energy Pyramids

Relationships

PredationThis is a feeding relationship in which one animal (predator) obtains its food by killing another animal (prey).

This relationship increases the predators chance of survival and reproduction at the expense of the preys.

AllelopathyThe production by a plant of specific chemicals that can be detrimental or beneficial to another plant.These chemicals influence the growth and development of neighboring plants by repelling predators and parasites, or poisoning competitors.

E.g. Camphor produced inleaves of the camphor laurel tree accumulates in the soil, preventing germination or growth of seedlings around each established group.

ParasitismA parasite obtains its food from a host. Although the host is harmed in some way, it does not necessarily die. Most free-living organisms have parasites. Many bacteria, viruses and fungi which cause diseases are parasites. Other relationships involve ticks, fleas and tapeworms.

Symbiosis A type of interaction between organisms where two different species live together in a close association. The association benefits at least one of them, and the other is not disadvantaged. The two types of symbiosis are commensalism and mutualism.

MutualismIf two organisms are more closely associated so that both benefit.

CommensalismA relationship that benefits one species and does not harm the other. The organisms are not dependent on this type of relationship: they could survive without each other.

Competition

Competition is the struggle between organisms for the same resource.

A particular ecosystem can support only a certain number of each type of species. Competition may be between members of the same species, or between members of different species.

Short term - competition reduces the chance of survival and restricts the abundance of all of the competitors.

Long term - one of the competitors will usually be more successful and drive out or reduce the numbers of other competitors.

Adaptations

Adaptation - a feature of an organism that makes it well suited to its environment and lifestyle.

Structural AdaptionsA physical characteristic relating to the structure of an organisms body.

Physiological AdaptationRelated to the way the organism functions e.g. Poisonous frogs

Behavioural AdaptationHow an organism responds to its environment e.g. Bird migration

Human Impact

Land Clearing

Introduced Species

Pollution

Extinction of Species

How Ecosystems Respond to Change• Wildfires are a relatively common event in

Australia. Many Australian plants have the ability to survive regular burning.

• Banksias – this plants ripe seeds can stay on the tree for years waiting for a fire to release them.

asgap.org.au

• Over time as Australia became warmer and drier - both plants and animals evolved with adaptations to enable them to survive this increasing aridity.

• Australia’s vegetation is dominated by two groups of flowering plants which have successfully evolved to colonise a wide variety of habitats – acacias (wattles) and eucalypts.