ULO D

• Biological Communities


  The term biological community refers to all the living components in an ecosystem. A slightly different concept is encompassed in the word biota, which refers to all flora and fauna, or plant and animal life, in a particular region.
• Predation


  A biological interaction where one organism captures and kills other organisms, its prey
• Symbiotic relationship


  Any close and long-term biological interaction between two different organisms
• Symbiont


  The organisms, each termed a symbiont, may be of the same or different species
• Mutualism


  A biological and ecological interaction where both organisms benefit from each other
• Parasitism


  A symbiotic relationship between species, where one organism, the parasite, lives on or in another organism, the host, causing it some harm, and is adapted structurally to this way of life
• Keystone species


  A concept introduced by Robert T. Paine in 1969, pertaining to species whose relative abundance has a disproportionate effect on its natural environment
• A population consists of all individuals of a single species that exist together at a given place and time
• A species is a single type of organism that can interbreed and produce fertile offspring
• All of the populations living together in the same area make up a community
• An ecosystem is made up of the living organisms in a community and the nonliving things, the physical and chemical factors, that they interact with
• Biotic factors


  The living organisms within an ecosystem
• Abiotic factors


  The physical and chemical features of an ecosystem
• Abiotic factors include resources living organisms need, such as light, oxygen, water, carbon dioxide, good soil, and nitrogen, phosphorous, and other nutrients
• Abiotic factors also include environmental features that are not materials or living things, such as living space and the right temperature range
• Energy moves through an ecosystem in one direction
• Niche


  A species' way of making a living
• Habitat


  Where an organism lives
• The important characteristics of a habitat include climate, the availability of food, water, and other resources, and other factors, such as weather
• Predation


  A relationship in which members of one species (the predator) consume members of another species (the prey)
• Competition


  A relationship between organisms that strive for the same resources in the same place
• Intraspecific competition


  Competition between members of the same species
• Interspecific competition


  Competition between members of different species
• Symbiosis


  A close relationship between two species in which at least one species benefits
• Mutualism


  A type of symbiosis where both organisms benefit
• Commensalism


  A type of symbiosis where one organism benefits and the other is neither harmed nor helped
• Parasitism


  A type of symbiosis where one organism (the parasite) benefits at the expense of the other (the host)
• Food chain


  An arrangement of the organisms according to the order of predation in which one uses another as a food source
• Trophic level


  The position of organisms in the food chain
• Food web


  A system in which numerous food chains are interconnected with each other
• In an ecosystem, all living organisms depend on each other for food which develops a food chain and in this way, they survive and reproduce
• All types of food chains have sunlight, producer, consumer, and decomposer as its components
• Community structure


  The number and size of populations and their interactions
• Community dynamics


  How the members and their interactions change over time
• Keystone species


  A species whose presence has inordinate influence in maintaining the prevalence of various species, the ecological community's structure, and sometimes its biodiversity
• Equilibrium


  A state where a community has a relatively constant number of species, with species identities and relationships changing over time
• Succession


  The sequential appearance and disappearance of species in a community over time after a severe disturbance
• Primary succession


  Newly exposed or newly formed rock is colonized by living organisms
• Secondary succession


  A part of an ecosystem is disturbed and remnants of the previous community remain
• Human activity is directly responsible for hundreds of extinctions in the last two centuries