Transcript ECOLOGY
Ecology • Definition: the scientific study of interactions among organisms and their environment – Branch of biology that was developed from natural history – Study reveals the relationships between living and non-living parts of the world Ecology The environment is divided into living and non living parts: • Abiotic – Physical factor such as: air, temperature, moisture, soil, light – These factors make up an organism’s habitat • Habitat: the area where an organism lives • Biotic: – All living or once living components of an ecosystem – Includes dead organisms and the waste of organisms Levels of Organization in Ecology To help ecologists understand the interactions of the biotic and abiotic parts of the world, scientists have organized the living world into levels: • • • • • Biosphere Ecosystem Community Population Organism Levels of Organization • Biosphere – The part of the Earth’s covering where life is possible • Goes from the top of the atmosphere to the bottom of the ocean; about 12 miles high! • Supports a wide variety of organisms • If the earth were shrunk to apple size, the biosphere would be thinner than the apple skin Levels of Organization • Ecosystem – A community of organisms and their living and non living surrounds • Living components of an ecosystem are the biotic factors • Non living components of an ecosystem are the abiotic factors Levels of Organization • Community – A group of various species that live in the same habitat and interact with each other • Population – group of organisms of one species that interbreed and live in the same place at the same time • Organism – living member of species Levels of Organization In a desert….. • Organism: coyote • Population: pack of coyotes • Community: pack of coyotes, hawks, owls, snakes, scorpions, & reptiles • Ecosystem: populations of animals listed above, cacti, shrubs, sand dunes, climate, rocks, temperature • Biosphere: the earth Biodiversity • Includes: – The variety of organisms within a given area – The genetic variation within a population – The variety of species in a community – The variety of communities in an ecosystem – Both abiotic and biotic factors help to determine the biodiversity of an area In an Ecosystem • Habitat: a place where an organism lives out its life • Niche: the specific role and position a species has in its environment. – Organisms may share parts of their niche, but never the whole thing! In an Ecosystem • Fundamental Niche: the entire range of conditions where a species can survive – Shaped by competition for resources between species • Realized Niche: the actual niche that an organism occupies within an ecosystem The establishment of a niche allows for several organisms to live in the same habitat while reducing competition for resources!! Changes in an Ecosystem • Succession: the replacement of one community by another at a single location over a period of time • First organisms to appear are pioneer organisms – Primary Succession occurs after natural disasters • Volcanic eruptions, fires, hurricanes, tornadoes, etc – Secondary Succession occurs after HUMAN involvement • Clearing of land for development, clear cutting the forest, etc Relationships in an Ecosystem • Symbiosis – Two species live in close association with each other. Can be positive or negative • Mutualism: both species benefit – Ex: cleaner shrimp/fish • Commensalism: one species benefits, the other does not, but is not harmed – Ex: orchids growing on trees • Parasitism: one species is helped while the other is hurt – Ex: Ticks on a dog. – The tick is the parasite and the dog is the host