Community and ecosystem ecology
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Community and ecosystem ecology



hello my name is Travis Mont this is one part in the series of videos involving ecology this video provide an overview of the community and ecosystem levels of ecology as well as examples for the concepts that are discussed here a scientific community can be defined as the interactions or relationships between different species of organisms an example these interactions can be observed in the food web diagram exhibited on this slide the ecosystem level of ecology would include all of the aspects of the community level plus it would involve all the nonliving or abiotic factors and the influence they have on these species all living things need energy one way that organisms can be classified is by the way that they obtain their energy some organisms generally referred to as autotrophs or producers make their own food most producers use energy from sunlight to do photosynthesis to make that food producers are the base of communities and provide directly or indirectly all the resources available for other organisms the amount of photosynthesis that can be done by producers that are present in an ecosystem is called primary productivity since more photosynthesis can be done where there is a high temperature and lots of water the amount of life that can be sustained in a community is determined by the amount of available sunlight and precipitation in an area the graphic on this slide shows that swamps and rainforests both hot and wet places are at the top of the chart for primary productivity and the tundra and desert both possessing very little available water at the bottom instead of producing their own food some organisms called heterotrophs where consumers opt to eat other organisms to obtain their energy there are many different classifications of consumers that are described on the left herbivores eat producers carnivores eat other consumers omnivores eat both consumers and producers and to try to borzi things that are already dead or dying you may also know them as scavengers decomposers are a type of detritivores that break things down on a chemical level an example of an herbivore might be now eating grass which is a producer carnivores such as lions eat consumers such as gazelle exclusively most humans are omnivores eating a diet of producers such as lettuce and consumers such as cows the vulture in this picture is an example of a Detroiter boring already dead of organisms and bacteria that break things down in a microscopic level would provide an example of decomposers there are a wide variety of species interactions that have and will be discussed later in this video to that you're probably most familiar with are shown and described in the slide predators are organisms that capture kill or consume others over a very short period of time while prey are organisms that are captured killed or consumed the garter snake in this picture is clearly eating the Newt the snake would be an example of a predator in this scenario while the newt would be an example of prey if you wanted to look at the linear feeding relationships between organisms how energy flows within a community what organisms are predators and which are prey you could look at a diagram like the one shown in this slide which is called a food chain at the bottom of each food chain there is a producer and then you may find a series of consumers and finally at the top you would find it a try devore and decomposer the picture furthest to the left green plants are the producers and collect energy from the Sun insects eat the plants small fish eat the insects large fish eat the small fish and hawks eat the large fish when the top consumers or potentially any other organisms die they can be chemically broken down by bacteria while a food chain may provide a simplistic overview of what eats what in a community few organisms utilize a single food resource so a food web is a more realistic way to show all of the complex interactions found within communities using spiders in this picture for an example not only do they eat herbivorous insects and predation sex but pradesh asst insects and insectivorous birds also eat them if you were to take a walk in a forest you would find a wide variety of organisms living there if you looked at the type of organisms found based upon their food source you may begin to notice that while there are a lot of producers or photo synthesizers there are fewer herbivores such as squirrels that could be classified as primary consumers that eat those producers it might take even more time to find carnivores or omnivores that could be classified as secondary consumers organisms that eat primary consumers such as the mouse that eats insects in this picture you could expect to find very few organisms that are classified as tertiary consumers which are heterotrophs that eat secondary consumers such as the snake that eats mice in this diagram the reason that you would find these results is that organisms need to use a lot of energy to maintain homeostasis or their internal conditions only about ten percent of the energy that an organism consumes can be utilized to grow and reproduce to be incorporated into those higher trophic levels to oversimplify things if you had a thousand kilograms of a producer it could sustain about 100 kilograms of primary consumer which can then sustain about 10 kilograms of secondary consumer and finally about one kilogram of tertiary consumer as the graphic on the bottom depicts the rest of this energy would be used for normal metabolic processes such as maintaining body temperature due to differences in temperature and precipitation in different areas throughout the world and therefore the primary productivity in these regions the number and the diversity of species in areas differs significantly species diversity or species richness describes the number and the variance of organisms that are found their species richness or diversity in various parts of the world are shown in the graphic to the right areas in red and orange have a very high species richness note that most of these locations would contain swamps or rain forest areas in blue and green have very low species richness many of these areas are in very dry and or very cold locations one additional factor that plays a role in the species richness or diversity in an area involves the size of the community and study as exhibited most clearly on Islands the larger the geographic area the greater the species richness in a community the graphic on this slide shows five different chains of island that exhibit this pattern clearly the bigger the area shown in the x-axis measured in acres the larger the number of species shown on the y-axis one reason that this concept is important is that the greater the species richness and species diversity in an area the more stable a community is if one of the hundreds of thousands of species in a rainforest were to be eliminated from the area another organism could probably fill its niche its role in the ecosystem in a desert area such as the one that's shown in grey and Australia the picture of the right species richness and diversity are so low 124 based upon this graphic that were one organism to be eliminated it might have considerable consequences on the rest of the ecosystem within a community every organism fills an important role some organisms refer to as keystone species can be very small in number within a community but play a ridiculously important role in shaping an ecosystem the elephant that's shown in the picture of the right is an example of such a keystone species savannas described in the video on biomes are essentially very warm grass lands that are commonly seen in Africa one major reason that the savannas look the way they do instead of being forested is that elephants knock over trees to reach all the tall leaves and to gain access to all the carbohydrate filled tree roots if elephants didn't perform their job the entire landscape would be drastically different another example of a species interaction that was described earlier is competition since many organisms have overlapping fundamental niches or the resources that they could possibly utilize in an environment there is competition or fighting for resources if two different members of the same species fight with resources with one another this is referred to as intraspecific competition when individuals of two different species fight for resources and to refer to as interspecific competition to distinguish between the two forms of competition you could think about college sports intramural sports occur within the same college intercollegiate sports occur between different colleges competition for resources is a lose-lose situation for all individuals involved so there are some strategies that organisms employ to avoid competition the picture on the bottom shows an agar petri dish with bacteria and a fungus on it while the bacteria grow very very quickly and efficiently the fungus produces a toxin to prevent bacterial growth this fungus is of the genus penicillium and produces an antibiotic called penicillin that was accidentally discovered when a scientist observed bacterial growth was inhibited on a discarded plate instead of competing for a resource this fungus decided to try to kill off the competition on the previous slide where bacteria in a fungus spot for the same resource one organism is eliminated in a strategy to avoid competition called competitive exclusion by eliminating the other species through higher efficiency or the production of toxins one organism can find success alternatively competition for resources can be avoided by a technique called resource partitioning the term partition means to divide into parts which describes what the organisms do they split up the resources instead of each of the species of bird shown in this picture fighting for nesting space throughout the entire tree Illustrated here as all the birds could potentially live throughout the tree each species decides to nest in a particular section of the tree and avoid competition with one another to avoid being captured killed or consumed by predators organisms employ a number of different strategy as discussed in the video on animal behavior organisms might form hurts the video on organism ecology suggested that some organisms may migrate to avoid unfavorable conditions if predation reduced the population cigna if you some organisms are cryptically colored to blend into their environment organisms such as snakes may produce toxins or as many of the butterfly is shown in the picture to the right just be distasteful the survival strategy that's exhibited on this slide is referred to as mimicry some toxic or distasteful organisms have colors or color patterns that are easily identifiable to potential predators some different toxic and non-toxic organisms have evolved similar color patterns and have avoided predation by doing so an example of this technique involves the monarch butterfly and Viceroy butterfly exhibited on the top of the picture to the right the monarch is distasteful or poisonous while the similarly patterned Viceroy is not Birds avoid eating both types of butterflies however because it's difficult to tell the two apart this type of mimicry where one organism is toxic and the other is not is called batesy and mimicry the bottom two sets of butterflies exhibit similar patterns of coloration and are all toxic predators identify all organisms with this pattern of coloration is toxic and as a result they avoid predation these organisms all of which are toxic exhibit mew Lyrian mimicry there are three classifications of long-term relationships between different species based upon the impact of that species has upon the other the first of these three types of relationships is called parasitism in this type of relationship one organism benefits while the other organism is negatively impacted hence the plus minus on the slide a parasite feeds upon another organism called a host while this relationship is somewhat similar to predation parasitism does not result in the immediate death of its prey parasites that live on the outside of an organism are called ectoparasites octo means on the outside the top picture of a tick would be an excellent example of this type of parasite as wood leeches and lice all of which lid on the outside of the body in the bottom picture on this slide dr. oz is showing Oprah a tapeworm that can be found in the digestive tract of its host since it lives on the inside of an organism and the prefix endo means inside it would be referred to as an endo parasite the prefix sin or sim means United we're together and the term biotic means life put the two together and you end up with a term symbiotic meaning living together symbiotic mutualism is similar to parasitism in the sense that it's a long term relationship between two organisms unlike parasitism however both organisms benefit hence the plus + describing the relationship on this slide examples of symbiotic mutualism involve a bee and a flower or a human and the bacteria in humans intestines bees help pollinate flowers while the flowers provide food for the bees humans provide bacteria with food while bacteria provide human with some essential nutrients such as vitamins both examples are win-win symbiotic commensalism falls somewhere between mutualism and parasitism one organism benefits while the other origin neither benefits nor is negatively affected hence the plus zero representing neutral on this slide an example of commensalism could be shown in the picture of the right involving a bird on a cow's back while the calstrs up insects for the bird to eat the bird does no real harm nor good for this cat in the circumstance if the bird happened to pick off parasitic insects from the cows back however this might provide an excellent example of symbiotic mutualism that is the end of this video summarizing the community and ecosystem levels of ecology if you're interested in learning about any other levels of ecology or any other themes of biology please subscribe to my channel thank you

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