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Transcript
What is an Ecosystem? An ecosystem includes all the different organisms living in a certain area, along with their physical environment. An ecosystem is like a car, all the parts work together to make the car move. If one part breaks, the car may not run. Ecosystems are not an isolated unit. They do not have clear boundaries. Ecosystems are composed of two factors: biotic factors: living parts of an ecosystem. Ex: animals, plants and micorganisms abiotic factors: nonliving parts of the ecosytem. Ex: temperature, sunlight, humidity, water supply and minerals Ecosystem have a level of organization. Organism (smallest) Population Community Ecosystem Biosphere (largest) organism - an individual living thing species - a group of organisms that are able to reproduce together and that resemble each other in appearance, behaviour and internal structure. Population - a group of individuals of the same species living in a particular place. Community - a group of interacting populations of different species Niche, and Habitat Habitat- the place where the organism lives; the specific type of area in which a plant or animal lives (on the planet). Niche- the way of life of an organism. This includes the area where the organism feeds, reproduces etc. It is biotic (living i.e. plants, other animals, humans) resources How Species interact with each other Within an ecosystem, different species can affect each other negatively or positively. We will look closely at five major types of species interactions: Predation Competition Parasitism Mutualism Commensalism Predation, predator, and prey the act of killing and eating another organism i.e. a lion kills a zebra the organism that kills and eats another organism is called the predator the organism that is killed and eaten is called the prey Competition the relationship between species that attempt to use the same limited resources Animals compete for the limited resources available to them. Resources can include food, sunlight, space etc. Parasitism the relationship between a parasite and its host Parasites are organisms that feed on or live within another organism without killing it immediately. However some parasites can lead to death. Examples of parasites = tapeworm, ticks, fleas, leeches The organism the parasite infects is called the host. Can you think of any reason why the parasite may not want to kill its host? Mutualism A relationship between two species in which both species benefit Ex. Anemones and clownfish are known to benefit from each other in an intimate relationship. The clownfish becomes immune to the stinging nematocysts of the anemone. The anemone provides protection and food scraps for the fish. The fish lures other creatures into the anemone's tentacles and may also remove dead and dying tissue from the anemone. Commensalism A relationship between two species in which one species benefits and the other species is neither harmed nor helped. Feeding Relationships, Three trophic levels Each species in an ecosystem belongs to a certain trophic (feeding) level based on their main source of nutrition. In studying the feeding relationships between organisms, we are actually looking at the living, or biotic, factors of the environment. Producers Consists of all plants, may also be called autotrophs. Has the ability to make its own food through photosynthesis. Supports all other feeding groups. Makes up the greatest amount of biomass on the planet. Eaten by consumers. Consumers consists of all animals. These organisms are not able to produce their own food so they must find their own food. They are also referred to as heterotrophs. There are 3 orders of consumers: 1st order = herbivores eat the producers (plants) i.e cow, sheep, deer etc 2nd order = carnivores eat other consumers (animals) i.e. lions, hawks, foxes etc 3rd and 4th = feed on other carnivores in the environment i.e. killer whales Humans are considered omnivores because we eat both plants and animals. Bears, pigs and other animals are also omnivores because they eat both. Decomposers Life forms that live on dead, dying or decayed plant and animal matter. Mostly consist of fungi and microscopic organisms, such as bacteria. Scavengers like ravens, crows etc help decomosers by breaking down dead material. Essential to the natural environment. They help to recycle nutrients back into the ecosystem. They break down animal excretions and dead organisms into simpler components that can be taken in and reused by producers. Food Chains Food chains can be written in a number of different ways, the simplest is: Sun producers consumers Food Webs All of the possible feeding relationships within an ecosystem are shown using a food web. Summary of food webs and food chains Within ecosystems there are producers, consumers and decomposers who transfer energy to one another through food chains or food webs. Trophic Level = the level in the food chain that an organims occupies. It can be producer, consumer, primary consumer, etc. Producers are the 1st trophic level and contain the most energy and each subsequent level has less and less energy. Food Chain = simplified way to show which organisms eat one another. Food web = represents all possible food interactions that can occur between certain organisms Optimal Living Conditions Each species will respond differently to these abiotic factors. The way that they respond determines where they will live. Different species will do well under different conditions. Every organism has an optimum, a level they thrive at. This is called the optimal zone. i.e. a good amount of water, sun etc. There is also a point where life is not possible. A high and low end of this range of optimance and this is the limit of tolerance. If an organism reaches this point they cannot survive. The stress is too much for them. Zones of stress exist between the optimal environmental and the high and low limits. The organism would experience levels of stress as they become closer to their tolerance limit.