Interactions within Ecosystems

• An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system.

Predation

• Predation is an interaction between species where one species, the predator, hunts, kills and consumes another species, the prey.
• The relationship between predator and prey can affect the sizes of both populations.

Parasitism

• Parasitism is a relationship where one organism, the parasite, lives on or in another organism, the host, causing it some degree of harm.
• Parasites are usually significantly smaller than their hosts, reproduce more quickly, and may cause diseases.

Mutualism

• Mutualism is an interaction between species where both species derive a benefit.
• An example of mutualism is the relationship between bees and flowering plants: bees get nectar to make honey, and plants get their pollen spread to other plants for reproduction.

Competition

• Competition may occur when resources are limited. It is an interaction between organisms or species, in which the wellbeing of one is lowered by the presence of another.
• Competition can affect how populations are distributed and structured in an ecosystem.

Effect of Environmental Changes

• Environmental changes can have profound impacts on ecosystems and can affect the interactions between species.
• Changes may be cyclical (like seasons), directional (like climate change) or caused by human activities (like habitat destruction).

Food Chains and Food Webs

• A food chain describes the eating relationships and energy flow between species within an ecosystem.
• A food web is a representation of the overlapping food chains that exist in an ecosystem.
• Both highlight the essential role of producers, consumers, and decomposers in an ecosystem.

Decomposers and the Nutrient Cycle

• Decomposers break down dead organic material and wastes, returning essential nutrients to the ecosystem, which can be reused by plants.
• This continuous cycle of nutrient use, decomposition, and reuse is called the nutrient cycle.

Sampling as a Means to Measure Distribution

• Scientists often use sampling techniques to predict the distribution of species within a habitat.
• Quadrats and transects are two common methods used to sample a population's distribution.

Endangered Species and Conservation

• Conservation efforts are key to preserving biodiversity, helping to save endangered species from extinction and retaining a balance within ecosystems.
• Many factors can cause a species to become endangered including habitat loss, hunting, pollution, and climate change.