ECOSYSTEMS & ECOLOGY Ecology is the study of the interactions of living organisms with one another and their physical environment.
ECOSYSTEMS & ECOLOGY A population consists of all of the individuals of one species that live together in the same area. A community is all of the different populations (different species) that live together in a defined area.
ECOSYSTEMS & ECOLOGY An ecosystem is made up of a community plus all of the physical aspects of the environment (like soil, water, sun, etc.)
ECOSYSTEMS & ECOLOGY A biome is a group of ecosystems that have the same climate & similar communities.
ECOSYSTEMS & ECOLOGY The biosphere is the entire living earth, where life exists, including land, water & air.
ECOSYSTEMS & ECOLOGY The place where an organism lives is its habitat. An organism’s niche is its place (role) in the ecosystem, including how it fits into the food web, the environmental conditions it needs in order to live & how it reproduces. No 2 species share exactly the same niche in the same habitat.
ECOSYSTEMS Abiotic factors – are all of the nonliving parts of an ecosystem (like weather, soil, gases and water). Biotic factors – are all of the living parts of an ecosystem (like bacteria, protists, fungi, plants and animals).
Energy Flow through Ecosystems Energy flows through an ecosystem in one direction: SUN AUTOTROPHS HETEROTROPHS Heterotrophs include animals such as carnivores, herbivores and omnivores. Sunlight is the main source of energy for all life on Earth.
Energy Flow through Ecosystems Producers (Autotrophs): Organisms that capture energy from the sun and turn it into food.
Energy Flow through Ecosystems Consumers (Heterotrophs): All animals that obtain energy by eating producers.
Energy Flow through Ecosystems Every organism in an ecosystem is assigned to a trophic level, which is determined by the organism’s source of energy (food sources).
Energy Flow through Ecosystems 1 st trophic level: Producers – plants, algae & bacteria 2 nd trophic level: Herbivores – All animals that eat plants 3 rd trophic level: Carnivores – All animals that eat herbivores (omnivores eat both plants & animals). 4 th trophic level: Top carnivores – Carnivores that eat other carnivores
Energy Flow through Ecosystems Decomposers: Organisms that break down organic matter (Example: fungi and bacteria)
Energy Flow through Ecosystems A food chain shows one path of energy flow in an ecosystem. Most ecosystems support more than one food chain and they generally interweave into a food web.
The amount of energy in an ecosystem can be represented by an ecological pyramid. Each trophic level contains less available energy than the level below it, so there are always fewer organisms in the higher levels of the food chain.
Energy Flow through Ecosystems Only about 10% of the energy available is within one trophic level is passed on to the next trophic level.
Succession Natural changes in the physical environment of ecosystems happen all the time. EXAMPLE: When a volcano forms a new island or fire burns all of the vegetation in an area and a new habitat is created.
Succession As an ecosystem changes, older inhabitants gradually die out and new organisms move in.
Succession These changes in plant and animal life that occur in a community over time are called ecological succession. Stages of Succession in a Pond
Succession When succession occurs on land where nothing has grown before it is called primary succession (Example: The invasion of plants from water to land) When succession occurs in areas where there has been previous growth it is called secondary succession (Example: A fire wipes out the entire plant & animal life in a forest and several years later new plants & animals are present.
Community Interactions Community interactions refers to the ways that animals and plants relate to each other. Competition occurs when organisms compete for resources such as water, food, light or space. Usually competition results in a winner and a loser, often with the losing organism’s failure to survive.
Coevolving in Opposition Predation: When one organism (the predator) feeds on another organism (the prey).
Symbiosis Symbiosis occurs when two species live closely together in relative harmony.
MUTUALISM Mutualism is a type of symbiosis that occurs when both organisms benefit from their association with each other. (Example: Lichens, Rhinos & tick bird)
COMMENSALISM Type of symbiosis in which one species benefits from an association and the other species is neither helped nor harmed. Example: Barnacles are organisms that attach themselves to whales to obtain a free ride to food sources, while the whale is unaffected by their presence.
Coevolving in Opposition Parasitism: A special type of predation where one organism (the parasite) lives in or on another organism (a host) and causes the host harm. Parasites usually do not intentionally kill their host since they depend on it for food, but often the host is fatally harmed by this association.
ECOSYSTEMS Limiting factor: Any factor that restricts the existence or number of organisms. (See the examples at right:)
ECOSYSTEMS Carrying capacity – The maximum number of individuals that an environment can support. As resources become less available, the growth of a population tends to slow or stop.