Ce diaporama a bien été signalé.
19 sept. 2010
Introduction<br />We find different organisms in different places. It is due to the fact that different organisms have the ability to do respond to the differnent environment. So inorder to survive in a new area the body features and the habits of an organism must be changed to suit to the environment. Different plants and animals have the ability to adopt to the changes in the environment. The ability of an organism to adapt to such situations is often called as adaptation. There are various types of adaptations by which organisms and plants survive.<br />Organisms and their environments <br />All animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat the plants. An organism's patterns of behavior are related to the nature of that organism's environment, including the kinds and numbers of other organisms present, the availability of food and resources, and the physical characteristics of the environment. When the environment changes, some plants and animals survive and reproduce, and others die or move to new locations.<br />All organisms cause changes in the environment where they live. Some of these changes are detrimental to the organism or other organisms, whereas others are beneficial. Humans depend on their natural and constructed environments. Humans change environments in ways that can be either beneficial or detrimental for themselves and other organisms. (National Science Education Standards Excerpts)<br />There are different ways in which plants and animals adopt to the environments. The adaptation could be one of them and there are other ways of behaving so that they best survive in the environment without being harmed or eaten bu=y othe r organisms.<br />Physical Adaptations<br />An example of a physical adaptation is when an animal changes colour to blend in with its habitat or when a leaf changes colour.<br />2952750<br />Fig.: Arctic fox are blue/grey in the summer and turn white in the winter!<br />32861252105025<br />Fig.: Leaves turn colour in the Fall to protect them from the cold. <br />Behavioral Adaptation<br />4095755410200One behavioral adaptation is hibernation. Some animals hibernate to survive the winter. They slow their heart rate and breathing so much it’s hard to tell that they are still alive!<br />Hibernates Aestivates<br />Deceptive Coloration<br />In deceptive coloration, an organism's color fools either its predators or prey. There are two types of deceptive coloration: Camouflage and Mimicry.<br />Camouflage helps an organism blend in with its surroundings. Camouflage can be colors or patterns or both. When organisms are camouflaged, they are harder to find. This means predators have to spend longer finding them. (http://www.nhptv.org/natureworks/nwep2a.htm)<br />Animal Mimicry<br />Mimicry is the similarity of one species to another which protects one or both.This similarity can be in appearance, behaviour, sound, scent and even location, with the mimics found in similar places to their models.( http://en.wikipedia.org/wiki/Mimicry)<br />Mimicry can be of three types<br /><ul><li>Batesian mimicry- It is named for Henry Walter Bates, a British scientist who studied mimicry in Amazonian butterflies during the mid- and late nineteenth century. It refers to two or more species that are similar in appearance, but only one of which is armed with spines, stingers, or toxic chemistry, while its apparent double lacks these traits. The second species has no defense other than resembling the unpalatable species and is afforded protection from certain predators by its resemblance to the unpalatable species, which the predator associates with a certain appearance and a bad experience. </li></ul>(Source: http://rainforests.mongabay.com/0306.html)<br />Muellerian mimicry- It is named for Fritz Mueller, a German zoologist who worked in the Amazon three decades after Bates. This form of mimicry refers to two unpalatable species that are mimics of each other with conspicuous warning coloration (aposematic coloration). Thus all mimics share the benefits of the coloration since the predator will recognize the coloration of an unpalatable group after a few bad experiences. Since several species have the same appearance to the predator, the loss of life will be spread out over several species, reducing the impact on each individual species. Poison arrow frogs of South America and Mantella frogs of Madagascar are examples with their conspicuous coloration of bright colors against black markings and toxic composition. <br />(Source: http://rainforests.mongabay.com/0306.html)<br />lefttop<br />2476503371850<br />Monarch Butterfly Mimics <br /><ul><li>Self-mimicry- It is a misleading term for animals that have one body part that mimics another to increase survival during an attack or helps predators appear innocuous. For example, countless moth, butterfly, and freshwater fish species have "eye-spots"?large dark markings that when flashed may momentarily startle a predator and allow the prey extra seconds to escape.</li></ul>Fig: Owl butterfly (Caligo idomeneus)<br />Location: Tambopata rainforest<br />(Source: http://travel.mongabay.com/pix/peru/tambopata-Tambopata_1028_4668.html)<br />Desert Plant Adaptations <br />Some plants, called succulents, store water in their stems or leaves. Some plants have no leaves or small seasonal leaves that only grow after it rains. The lack of leaves helps reduce water loss during photosynthesis. Leafless plants conduct photosynthesis in their green stems. Long root systems spread out wide or go deep into the ground to absorb water. Some plants have a short life cycle, germinating in response to rain, growing, flowering, and dying within one year. These plants can evade drought. Leaves with hair help shade the plant, reducing water loss. Other plants have leaves that turn throughout the day to expose a minimum surface area to the heat. Spines to discourage animals from eating plants for water. Waxy coating on stems and leaves help reduce water loss. Flowers that open at night lure pollinators who are more likely to be active during the cooler night. Slower growing requires less energy. The plants don't have to make as much food and therefore do not lose as much water. <br />190506315075 <br />Fig: This cactus displays several desert adaptations: it has spines rather than leaves and it stores water in its stem.<br />Source: Copyright © 2009 Missouri Botanical Garden<br />Photoperiodism<br />The response of plants to the relative length of day and night is called photoperiodism. Plants actually "
the duration of darkness rather than of light. Plant response to day light length is caused by changes in a pigment called phytochrome. Phytochrome is a light-sensitive, blue-green pigment. It occurs in plant tissues in minute quantities. The pigment activates certain processes without itself being used up. During daylight, phytochrome is converted to an active form, and in darkness it is converted to an inactive form. If the active form of phytochrome gets to a specific level for that plant, the enzyme can start changes in the plant. CITATION Mas99 l 1033 (Mason, 1999)<br />Photoperiodism influences many activities in plants including growth, seed germination, flowering, fruit development and the onset of winter dormancy. Some plants need a specific period of daylight in order to flower. Some plants require short days or long nights to flower. Some plants require a short day and long night to bloom. In plants referred to as short day, their flower bud formation begins when daylight is relatively short about ten to twelve hours and flowering is suppressed if daylight is longer. Greenhouse growers manipulate light to get the plants to bloom at the prescribed time. CITATION Mas99 l 1033 (Mason, 1999)<br />Long day and short night plants initiate flower bud formation once they are exposed to relatively long days and short nights, about fourteen hours or more and won't flower if daylight length is shorter. Some common vegetables such as beet, radish, lettuce, spinach and potatoes are long day plants. Bulbing in onions is initiated under long days. The amount of daylight required depends on the variety. Some plants don't care about day length to flower and are called day neutral plants. Howeer all this plant response may change depending on temperature, humidity and maturity of the plants. CITATION Mas99 l 1033 (Mason, 1999)<br />The Fight or Flight Response : Instinct Rules<br /> All animals have a built in survival instinct that has helped ensure that the fittest survive to propagate the species. The slowest wildebeest in the herd is the one that becomes supper for the lions! This instinct is alive and well, and functioning in each and everyone of us. In order to mobilise our bodies to meet the perceived threat, we prepare for either fight or flight. Our body begins to close down all extraneous functions, blood is pumped to the main muscles and away from the skin (pale) sugar is metabolised by the adrenalin, pupils dilate, digestion stops, skin sweats, breathing becomes shallow. In this state we are only fit for survival. We can’t listen, we can’t be creative we are a victim of this mechanism. CITATION Coo10 l 1033 (Cooke, 2010)<br />In the past our ancestors existence was utterly dependent on how well they read and responded to danger. Those methods for recognition and response to threat were literally hot-wired into their systems. They have been passed down through generation after generation and underpin the reactions to danger we experience today. The fight or flight response is automatic and by-passes the rational or conscious mind. We do not consciously choose to feel threatened or suffer anxiety. It is an instinctive response, happening unconsciously, of its own accord. CITATION Sus06 l 1033 (Dugdale, 2006)<br />Chemical alert at physiological level<br />When the response is stimulated at a physiological level, a part of the brain called the hypothalamus sets off a series of actions preparing the body for either battle (facing the danger) or running (escaping the threat).<br />Chemicals such as adrenalin, noradrenalin and cortisol are released into the bloodstream and complex patterns of nerve cell firing occur. The body is put on a state of high alert. The breathing and heart rate quickens. Our muscles are tightened. We become hyper-vigilant and sensitive and our body’s entire focus becomes repelling the threat.<br />Bodily functions deemed non-essential are slowed down as the energy keeping them in optimum functioning condition is temporarily refocused elsewhere. Because you don’t usually stop to either make a speech or grab something to eat while fighting or running for your life, the systems governing digestion or voice are affected. The degree to which we feel challenged directly corresponds to the loss of functioning we experience. The symptoms range from mild to severe accordingly.( http://www.write-out-loud.com/fightorflightresponse.html)<br />Conclusions<br />References<br /> CITATION Mas99 l 1033 m Mas99(Mason, 1999; Mason, 1999)<br /> CITATION Sus06 l 1033 (Dugdale, 2006)<br /> CITATION Coo10 l 1033 (Cooke, 2010)<br />