Biology Ecosystem Chapter 9 PDF

Connections Between Living Things 1. Ecosystems 2. Material Circulation and Energy Transfer within the Ecosystem 3. Ecosystem Conservation 4. Human Life and Nature  Section 1: Ecosystems Recently, the word “eco” can be heard a lot: this is an abbreviation refer...

Connections Between Living Things 1. Ecosystems 2. Material Circulation and Energy Transfer within the Ecosystem 3. Ecosystem Conservation 4. Human Life and Nature  Section 1: Ecosystems Recently, the word “eco” can be heard a lot: this is an abbreviation referring to either “ecosystem,” the interrelations between organisms and their environment, or “ecology”, the study of ecosystems. In common speech, it refers to anything related to the environmental challenges we face today. Now, let’s take a look at what ecosystems are. 1. Populations, Communities, and Ecosystems 1. Ecosystems A group of individuals of the same species living in the same geographical area is called a population. A population contains many different relationships between its individuals, but also has relationships with other populations. These relationships between organisms are called interactions. The lives of organisms also relate to the abiotic components of their environments, such as air, water, temperature, and sunlight. The influence abiotic factors exert on biotic factors is called an action, while the influence biotic factors exert on abiotic factors is called a reaction. 192  A group of populations that live in the same area and interact is called a community; a community living in conjunction with the abiotic components of its environment is called an ecosystem. In other words, an ecosystem can be defined as “a system made of a community and the abiotic components of an environment.” 2. Interactions When the population of one species affects the lives of a population of another, this is called an interspecific interaction. This includes competition, symbiosis and predator-prey relationships. 3. Food Chains In communities, animals and a tiny fraction of plants eat other organisms: when they do this, they are referred to as predators. In contrast, when they are eaten by other animals, they are referred to as prey. For example, in the African savanna, the grass (prey) gets eaten by herbivores such as zebras (predator), while zebras (prey) get eaten by carnivores such as lions (predator). In this way, organisms have a series of predator- prey (eat - be eaten) relationships that are linked together: this is called a food chain. Most animals consume a variety of organisms as food, meaning the predator-prey relationships are often not linked together as one chain but in a complex web. For this reason, the term food web is also used. In food webs, the direction of the arrow indicates where the nutrition is going. ① Producers and Consumers Plants, through photosynthesis, produce sugars from water and carbon dioxide as well as proteins from inorganic nitrogen. On the other hand, animals, who cannot produce organic matter from inorganic matter, get their organic matter from plants. Organisms that generate food for themselves are called producers, while animals who eat other organisms for food are called consumers. Consumers come in levels: animals that eat plants (herbivores) are primary consumers; animals that eat primary consumers are secondary consumers; animals that eat secondary consumers are tertiary consumers. 193 Some examples of primary consumers are: grasshoppers, butterflies, rabbits, deer, and sea urchins. Secondary consumers include dragonflies, frogs, lizards, and sardines, and tertiary consumers include owls, foxes, and tuna. Quaternary consumers, who prey upon tertiary consumers, and quinary consumers, who prey upon quaternary consumers, also exist. These divisions of the food chain based on the successive intake of nutrition are called trophic levels. As we go from primary consumers to secondary consumers and tertiary consumers, the higher the trophic level gets. It is possible for an animal to be a secondary consumer and a primary consumer at the same time, or even to be a quaternary consumer and primary consumer at the same time. Furthermore, the same species can be at a different trophic level depending on the area it inhabits. ② Food chains on Land On land, plants such as trees and grass act as the main producers, creating organic matter through photosynthesis. These plants are eaten by primary consumers such as grasshoppers, butterflies, squirrels, mice, rabbits, and deer. These primary consumers are eaten by secondary consumers such as frogs, dragonflies, lizards, snakes and shrikes. These secondary consumers are eaten by tertiary consumers such as owls, foxes, weasels, and wolves. Examples of quaternary and quinary consumers in Japan include birds of prey such as the golden eagle and marine mammals such as sea lions. 194 Herbivores (primary consumers) consume many different parts of plants, such as the organs (the root, stem, and leaves), the seeds, and the fruit. Their teeth and digestive systems have structures suited for plant-eating (See Chapter 3). Herbivores have also developed systems in which they can look out for predators whilst eating. Though this makes it difficult for carnivores to catch them, carnivores have similarly developed systems to catch prey more easily. In this way, complex food chains have developed among organisms, starting from the photosynthesis of plants. ③ Food Chains in the Soil There are many organisms and predator-prey relationships that exist within the soil. Here, the fallen leaves and plant roots act as the producers. These get eaten by primary consumers such as earthworms, roly-polys, millipedes, and nematodes. The primary consumers are eaten by secondary consumers such as mites, centipedes, and moles. For example, moles mainly eat earthworms, who eat fallen leaves; even underground, plants are the starting point of the food chain. It should be noted that these food chains are usually not contained entirely within the soil, and connect to the food chains that take place above ground. 195 ④ Food Chains in the Water Food chains are also present in rivers, lakes, and oceans. In the ocean, algae, including both smaller forms such as diatoms and larger forms such as kombu, perform photosynthesis and act as the producers. These producers are eaten by primary consumers such as animal plankton, shellfish, and sea urchins. Primary consumers are then eaten by secondary consumers such as sardines, seabreams, and starfish. Small fish such as sardines are eaten by fish of higher trophic levels such as sharks and tuna. ⑤ “Food Chains Cannot Destroy a Species” Take the example of an underwater food chain. A species of animal plankton (primary consumers) may get eaten by secondary consumers such as horse mackerel and Japanese anchovies, but they will not die out as a result of this. Similarly on land, grasshoppers (primary consumers) will not die out even as they get eaten by frogs and shrikes. This is because they are much more numerous than the amount their predators eat, and also have much higher reproductive capacities. ⑥ “Apex Predators will not Increase Infinitely” Animals with the highest trophic levels, such as golden eagles, owls, lions, and sharks, are almost never eaten by other animals. However, this does not mean they will increase infinitely in number. When they start increasing, the number of animals they eat decreases and limits the food supply, illnesses can spread, or the number of offspring and eggs they produce can decrease. These factors which inhibit the increase in the population of organisms are called environmental resistance. 196  2. Population Relationships and Interspecific Interactions 1. Balancing Populations A female sardine spawns tens of thousands of eggs in one go. However, this does not result in sardines dominating the ocean; All the fish increase and decrease in numbers repeatedly to maintain a general ratio. Similarly, one dandelion contains around 100~200 seeds, but this does not result in the earth being covered with dandelions. Let’s look at an example of organisms in a lake. Water lilies float on the surface of the water, while water thyme grows in the depths. Insects such as water striders move across the surface while fish such as medaka swim right below. At the bottom live pond loaches and dragonfly larvae. When spring comes and it gets warmer, phytoplankton increase rapidly and turn the water green. River snails and fish become active as a result. When the water cools down in autumn, phytoplankton decrease and the colour becomes clear. In this way, the number or behaviour of organisms in a particular area changes over the course of a year, but will repeat itself and remains constant over the year unless there is an interruption from outside. This is because the lives of the organisms are closely related to each other through the food chain, as well as to abiotic factors such as temperature and the amount of oxygen and light. These close connections between organisms and the environment that stabilise each other are the natural workings of an ecosystem. 2. Ecological Pyramids Let’s look at the relationships between the number of organisms at different trophic levels. The table below shows the weight and population of different mammals in a 114 km2 area in Africa, divided into herbivores and carnivores. We can see that the weight and population of primary consumers (herbivores) is much smaller than those of secondary consumers (carnivores). Number of Individuals Total Weight Carnivores 35 2.5 t Herbivores 3400 400 t Plants N/A 57,000 t 197  If we arrange the biomasses of organisms in the order of trophic levels (from low to high), we get a pyramid-like shape. This is called an ecological pyramid, which tells us that the biomass of what gets eaten is always greater than that of what eats it. In order to live, we need an amount of food much greater than the size of our bodies. This is because the food we consume does not only go towards structuring our bodies, but also towards energy and maintaining its functions. Out of the total amount of organic matter a consumer eats, less than 10% is used for the growth of the body; More than 90% is used for basic functions of living such as moving and breathing. Essentially, for a primary consumer to live, it needs a much greater amount of producers than itself to exist. For a secondary consumer to live, it needs a much greater amount of primary consumers than itself to exist. This indicates that the biomass of organisms in a given area is determined by the amount of producers. In the previous example (p.197), the amount of plants per carnivore is roughly 1629 t (57000÷35≈1629). Though carnivores do not directly consume plants, this amount is needed for the number of herbivores they need to survive. ➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖ Different Ecological Pyramids There are different types of ecological pyramids: A pyramid of number depicts the total number of individuals at different trophic levels; a pyramid of biomass depicts the total biomass at different trophic levels; A pyramid of energy shows the amount of organic matter in terms of energy that flows from one trophic level to another. However, with parasitic food chains, the pyramid of numbers is inverted. For example, on one cherry blossom tree, there are hundreds of caterpillars, and on a caterpillar there are thousands of wasp larvae and mites. 198 3. Balanced Regulation of Animals in Nature The population of organisms that live in a certain region repeatedly somewhat fluctuate in nature however, still remains mostly constant. For example, let's say that a grassland expands after a mountain fire, and herbivores (primary consumers) grow in population. Then, these primary consumers will eat the grass, and therefore the amount of grass will decrease. As the number of herbivores increases, the number of carnivores(secondary consumers) will increase. Then, the loss of food and the number of predators will become greater, and the number of primary consumers will decrease. Because of this, the grass will not be eaten as much allowing it to grow, and the number of carnivores will decrease due to the decrease in population of its prey. As a result, the ecology pyramid will remain balanced out. A common example of this is the fluctuation in the population of the snowshoe hare and the lynx in Newfoundland in Canada. The lynx eats the hare, and when the population of hare increased, the number of lynx increased. When the number of the lynx increases, the number of hares greatly decreases. 199 This drastic decrease in the hare population not only affected the predation of lynxes, but also decreased the number of grass and the birth of baby hares , and caused the delay in growing new grass. However, when the plants get plucked from the roots due to large disturbances such as deforestation, countless animals in a certain area can be killed in the process, predators can be moved to regions with no competition, and as a result, the balance in ecology developed through a very long time can be destroyed, and may not go back to the original balanced state regardless of time. ➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖ From a prairie into a desert Until around the 19th century, there was a large prairie in the midwest of North America. In the prairie, there were about 60 million large wild cows known as american bison. These American bison were predated by multiple coyotes and wolves. Often other animals like the prairie dog, hares, and weasels were seen. However, now this field has turned into a large desert, and the past scenery is gone.Since the end of the 18th century, bison were hunted with guns. It began for the purpose of food and wool, but it gradually turned into a sport. The bison that existed 60 million are almost gone in merely 70 years, Moreover, with the domestic horses stomping into the burrows of prairie dogs, the prairie dogs were also killed. With the animals gone, cows and sheeps were released into the field. However, not only did these animals eat all the grass, they stomped all over the soil needed by the plants. If the prairie dogs that made burrows were still there, the soil would not have been trampled by these animals. With the plants gone, the top soil washed off with the rain, and the soil became dead and the plants couldn’t grow. Like this, the land once filled with grass and life became a desert. 200  4. Interspecific Competition Interspecific competition is one of the interactions species have with one another, and it is formed by the space and food competition between different species. Moreover, when these 2 types of species interact with one another in a way that the existence of one negatively affects the other, these species exist in an interspecific competition. Normally, species in an interspecific competition exist in the same niche. For example, if 2 species live in the same space and eat the same food, there is limited food, and therefore one species eating more will decrease the population of the other species. In these situations, these 2 animals exist in competition in regards to food, and the species with the lower population has lost. Competitions exist with other resources. It can be of space to nest, territorial reasons and more. Also, species with close relationships with one another often have similar necessities in life and therefore become important competitors. Like the lion and the hyena, some physically compete with one another for food, however, most of the time, these competitions occur indirectly, For example, medaka and mosquitofish are extremely similar. Though in the past, medaka were commonly found in the city, in recent years, they have been superseded by mosquitofish. However, this does not mean that the mosquitofish are eating the medaka or that it is directly attacking the medaka. There are situations where competition exists even between species that do not require the same resources. An example of this is sea urchins and seaweeds. As sea urchins eat seaweeds, they have a prey→predator relationship. However, when the sea urchin occupies the space on the bedrock, the new seaweeds are eaten quickly, and new seaweeds cannot grow. However, when the seaweeds move with the waves and dominate the space on the bedrock, the baby sea urchins cannot colonise and therefore cannot live. Like this, the prosperity of one hinders the other’s chance of survival, making this relationship a competitive one. 201  ➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖ Territory of the Parus minor Individuals of the same species are often competing against one another as they cover the same niche. However, there are situations where a system is made to avoid competition as competition can create disadvantages for the species. An example of this is territories and order, Territories are spaces each individual gets, and competition is avoided by other individuals not entering another's territories. Moreover, they avoid competition by having an order in which individuals eat their food. 5. Symbiosis Symbiosis is when several species live in a mutual relationship in the same space, or with interaction with one another. Those easy to distinguish the relationship of the 2 interacting species have names. ① Mutualism (cohabitee ⇄ cohabitee) A mutually beneficial relationship ② Commensalism (cohabitee → cohabitee) A one-sided symbiotic relationship ③ Amensalism One-side is harmed while the other has no effect ④ Parasitism host (parisitized) → parasite (parasitize) One-side is harmed while the other benefits People often think of mutualism when they hear the word symbiosis. However there isn’t a definitive separation in the symbiosis of populations. The interaction can change even within the same species and the interaction can change as a result of environmental change. Moreover, even with the same phenomenon, with the difference in time and space, there are cases where it does not cause harm or benefit to its cohabitees. Symbiosis is not something that can be simply categorised with its harm-benefit relationship. 202  Without thinking about the harm-benefit relationship, symbiosis is the state where numerous species live in the same space with interaction to one another. Once symbiosis and parasitism were thought to be different phenomena however, it was seen that the one was gaining something whilst the other was being harmed by the other was caused by the balance regarding organism interaction, and it was understood that it cannot be separated clearly between the two. As a result of this, now, symbiosis— the relationship species have with one another– includes all the interactions, including mutualism and parasitism. Parasitism is a type of interaction between organisms, and therefore is symbiotic, and is a part of “the interaction several species of organisms have living in the same space”. Parasitism includes the following requirements between organism A (parasite) and organism B (host): A receives nutrition from the nutritional sources B has obtained, or should obtain. A must be within B's body, on the surface, or in a position close to it. The above relationship continues for some time. B suffers a clear disadvantage due to the existence of A. Nematodes, which live in human intestines and absorb the foot inside, and lice, which suck blood whilst living in the hair and clothes of humans, are quintessential examples of parasites. However there are parasites that only interact for a short period of time, such as mosquitoes and horseflies, which suck human blood and leave soon after. There are examples that are difficult to distinguish. For example, leaf-eating insects such as the caterpillar eats the leaves of trees does fit the definition however, this is often seen as prey (planter) and are not considered parasites, However, if you rearrange the plant tissue and create a gall, insects that live and eat the inner tissue are called parasites. 203  ➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖ Survivorship curve Lifespan varies with species. However, regardless, all organisms living in nature experience environmental obstacles including lack of food and space, sickness, and competitions. As a result of this, most individuals cannot live as long as their species lifespan. In biology, organisms not being able to live as long as their lifespan due to environmental obstacles are known as the ecological lifespan, and the lifespan without environmental disturbances are known as their physiological lifespan. The survivorship curve shows how the population decreases with growth. The growth below shows the survivorship curve of a type of a heron. From the graph, it can be seen that in nature, the death rate is steady in contrast to the huge increase in death with old age in the breeded heron line. In breeding, they are less likely to be affected by environmental disturbances and therefore are able to live as long as their physiological life span. 204  3. Action/Reaction There are various differences in body shape and lifestyles between individuals that live in different environments as a result of how the environment they are in acts upon them. Moreover, with the action-reaction between individuals and their environment, populations that make up the ecosystem changes even within the same environment. 1. Intraspecific mutations found in populations Mammals and birds have a trend in which their body surface area to body weight ratio decreases (Bergmann's rule), and the arms and ear length shortens in comparison to its body size (Allen’s rule), as the temperature drops from equator to the poles. This is because the amount of heat released from the body decreases as the surface area to weight ratio of the body decreases, allowing the body to maintain its temperature. 205  2. Plant life-form Plants often have the ability to change shape and function depending on the environment in which they grow. Life-form is the categorization of the way they live in regards to them and their surrounding environment. There are 3 ways of approaching this, as stated by Raunkiaer– dormancy form, reproduction form, and growth form. ① Dormancy form (Raunkiaer’s life-forms): Dormancy forms are identified based on the location of the dormant bud: - Underground plants…Dormant bud is underground - Semi-underground plants…Dormant bud is below the surface - Surface plants…Dormant bud is 0~0.3 m above ground - Shrubs (small above-ground plants)…Dormant bud is 0.3~2 m above ground - Small ground plants…Dormant bud is 2~8 m above ground - Middle and high trees and low trees…Dormant bud is 8~30 m above ground - Aquatic plants…Dormant bud is in the water - Annual herb…Passes the winter as a seed ② Reproduction form: These are divided into the underground organ type and the spray organ type ③ Growth form: These can be divided into the following types; upright type, branched type, soybean type, vine type, crawling type, rosette type (Exists first as a rosette, then the rosette withers and it turns into the upright type), pseudo rosette type(it starts off in the rosette form, and it later changes into the upright type with the rosette leaves still present) 3. The succession of plant communities Research on successions started with the investigation in the shallow lakes. Often, lakes become more shallow as the sand and remains of plants accumulate. As the water becomes more shallow, the types of plants present change, transforming the environment from wetlands to dry meadows and vice versa. This change was first discovered in the 17th century by a research of wetlands in Iceland by Kings, and was later identified in various places across the globe. Moreover, by research done by the botanist Eugen Warming in 1891, it was discovered that by pioneer species invading, the sand movements stop and the land that was once bare is able to change into a grassland. He published this as plant ecology, and stated that this phenomenon can be seen in different lands across the globe, and also states some common trends in succession. 206  After this, ecologist Frederic Clements published a book in which he put forward new ideas such as primary succession, secondary succession, xerarch succession, hydrarch succession, and also made clear the existence of a climax at the end of the process. ① Common trends in succession - In the beginning of succession, algaes and lichens grow, and later become more complex plants and become moss, and finally turn into plants with vascular bundles. - In some regions, the number of types of species is limited, and grows in number of different species with time, and eventually will have the most number of species, which eventually decreases through time and competition. - Within plants with vascular bundles, the succession goes in the order of annual herbs, biennial herbs, perennial herbs, and trees. - In the beginning, the height of the plant community is low, however, it grows with time, and later stabilises once it grows to a certain height. - Trees grow in the order of intolerant trees (sun trees) to shade trees, - The types that invades first are mostly the seeds carried by wind, water, birds, and animals ② Intolerant trees and shade trees Intolerant trees are trees that are adapted to growing in the sunlight, and are unable to sprout or grow without sunlight. Shade trees are able to grow in the shade (especially as a young tree), and are able to grow in places with both sunlight and shade. When looking at the difference between the leaves of intolerant trees and shade trees, both shade leaves and sun leaves in shade trees while intolerant trees have no difference in leaves. Palisade tissues do not develop well in shade leaves, and often have thin and large leaves. As a result of this, they are able to absorb light in weak light and therefore can create materials efficiently. In contrast to this, sun leaves are made in strong light, and have 3~4 layers of palisade tissues, and have a large photosynthesis capacity and respiration capacity per unit area, and therefore are able to create substance efficiently under strong light. These differences in leaves may be the reason behind the changes from intolerant trees to shade trees. 207  ➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖ Succession and Soil formation Professor Tezuka Yasuhiko of Kyoto University/Tokyo Metropolitan University published his findings of the plant communities and soil formation found on the Miharayama volcanic ejecta in Izu Oshima in 1961. Izu Oshima is thought to have lava from the 2000s, Yasunaga lava of 1778, and lava from 1950 and 1951. All these lavas have been labelled from A~I, and have been set to a point in which its plant and soil has been researched from both sides. The land with the new lava, A~C, had volcanic wastelands, D and E had shrub forests, F and G had Mixed forests of evergreens and deciduous trees, while H and I had evergreen broad-leaved forests. Looking at the figure on the right, the shift in plant types from wasteland to evergreen broad-leaved forests are very clear. Moreover, when the plant successions and soil formation is observed and compared with the different lands, the shift in plant population, succession, and the development of soil is very clearly seen. 208  4. Decomposers of the biological world 1. Organisms in the soil Organisms all follow the cycle of creating offspring, and dying. And though animals leave its excreations on its path, the ground never seems to be covered with it, and they naturally disappear with time. ① Where do fallen leaves go? Fallen leaves accumulate in forests however, forests never overflow with them. So where do these leaves go? When observing the leaves accumulating on the ground, there are many that are dry and still hold the shape of leaves, However, those below hold moisture and are often darker than those above as if they are pushed down by the leaves above, and do not hold the shape of leaves. Moreover, the leaves even below are somewhat black in colour and have lost their shape and are much more broken and small. Those even below these leaves are almost black, and are like fluffy soil. Fallen leaves are the corpses (remains) of plants. In the forest, there are many organisms that live by eating these fallen leaves. These leaves get eaten by the small animals, and become nutrients of bacterias and fungi underground, and get decomposed. Soils have some moisture and therefore do not fry, and have organic matter (remains of leaves and animals, and excreations) that small animals eat, and therefore have many small organisms living in them. There are countless animals that live in the forest however, 80~90% of them are organisms that live in the soil. In the soil, the depth that organisms live in are up to 30cm, and of this, the soil 5cm underground is where the soil has the most number of species. ② Organisms in the soil So many organisms live in a small amount of soil, and they live by eating organic matter such as the remains and excreations of other animals. Roly-polies, woodlouses, and millipedes bite into fallen leaves, earthworms and slugs eat moist leaves, carrion beetles and carrion beetles eat the remains of other animals, and geotrupidae and nematodes eat the dung of animals. Predators such as centipedes and spiders survive by eating these animals. 209  Soil is an environment in which fungi and bacteria are able to live and plants are able to thrive because of these animals. For example, earthworms eat and digest dead leaves and grass, and return the undigested material back into the ground. This undigested material is excreted in a sphere form, and is fluffy with air and holds moisture. Soil that covers the earth’s surface, where organisms can live in, is made by the mixture of clay from weathered rocks, sand, fallen leaves, and organic matter from decomposed corpses. ③ Microorganisms in the soil Other organisms besides small animals such as bacterias and fungi also live in the soil. In 1g of soil, it is said that there are a few million bacterias and fungi present. Fungi belong in the same category as mould and mushrooms– they elongate their hyphae to take in animal corpses and fallen leaves to decompose them. Bacteria include bacillus subtilis and lactic acid bacteria, and they digest animal corpses and excretions. Fungi and bacteria excrete their digestive juice from their body surface, and digest and take in the corpse and excretion’s glucose and amino acids to use it as energy source. As a result of this, the organic matter that corpses create are broken down into inorganic matter such as water, carbon dioxide, and nitrogen. This inorganic matter is then used in plants. 210  Let’s observe the organisms underground. (1) Set up an apparatus like the right. (This is called the Tullgren apparatus) (2) When the lamp is turned on, the organisms drop into the ethanol as they dislike light and heat. This can then be observed under the loupe and microscope. Functions of microorganisms in the soil (1) Divide the organisms you extracted from the Tullgren apparatus into 2, and bake one of the soil (2) Put both into beakers with weak glucose solution, and connect them to a plastic bag with limewater like the image on the right, and leave it for 2~3 days In the experiment, the unbaked soil made the limewater cloudy however, the coal water with the baked soil did not change. From this, we are able to understand that there are countless bacteria and fungi in the soil unseen by the naked eye, and that they breathe with organic material such as glucose and exhale carbon dioxide. ④ Decomposers Earthworms and roly polies, fungi, and bacteria have the function of decomposing organic matter from corpse and animal excretions into inorganic compounds. Of the inorganic compounds made from this, nitrogen oxide is absorbed by the roots of plants, and is used as an ingredient in plant growth. 211  Moreover, carbon dioxide and water are used as reactants in photosynthesis. Like this, the organic compounds made by producers ultimately end up as inorganic compounds. The organisms responsible for this are known as decomposers. Decomposers are heterotrophs in terms of their nutritional form however, in contrast to them being able to synthesise organic matter from inorganic matter, they are also able to decompose organic matter into inorganic matter to allow producers to reuse them. ⑤ Decomposition by fungi (mould, mushrooms) Fungi do not contain chlorophyll, and therefore are unable to create their own nutrients. As a result of this, they take in nutrients from other organisms, corpses, excreations, and organic matter. For example, mould and mushrooms surround their hyphae around fallen leaves, branches, and trunks in the forest, along with animal corpses and excretions. These hyphae can grow from cell to cell in the tissues of xylem (where the vessel elements are clustered) and bark, and they decompose the organic matter for them to grow, and use them as energy. As a result of this, the organic matter in the cells of xylem and barks turn into inorganic matter such as carbon dioxide, nitrogen compounds, and water, and are released into the air and ground. Mould and mushrooms usually increase population with spores. When the spores germinate, the body grows in the form of a thin thread-like substance known as hyphae. Many hyphae gather together to form a fruiting body, and this fruitificated form in the mushroom, and all the others are mould. There are many forms of this including the most common known mushroom shape. Bacterias do not have hyphae, however they are also able to decompose organic matter much like moulds and mushrooms. With the existence of decomposers, corpses and excretions are converted into inorganic matter that plants are able to absorb, and therefore the ground will cease to be covered with corpses and excretions. 212  Section 2: Material circulation and energy transfer within the ecosystem Organic matter produced by plants and seaweed (producers) move into other organisms through the food chain, and get decomposed by decomposers such as fungi and bacteria, to go back into the soil. Like this, matter constantly moves in cycles, and we will observe this in this section. 1. Material circulation within the biological kingdom 1. Carbon cycle Carbon dioxide and water on the surface of the earth get absorbed by producers such as plants and seaweed and get converted into organic matter and oxygen with light. The organic matter created by these producers is not only used by producers themselves but is also consumed by consumers/animals, and become nutrients for animals. Corpses of animals and plants get decomposed by decomposers and get converted back to carbon dioxide and water, and go back into the soil. While oxygen is released into the air as a result of photosynthesis by producers, they are used for breathing by producers, consumers, and decomposers, and therefore matter used by organisms circulate the earth and animals in this way. 2. Oxygen cycle Organic matter are compounds containing carbon. Though our body is made of organic matter, most carbons in organic matter are made off of carbon dioxide in the air. Carbon dioxide in the air is absorbed by plants and seaweed and is converted into organic matter through photosynthesis. Carbons that are organic matter flows from producers to decomposers for decomposition through the food chain and is the ingredient for breathing for them. Breathing is something all organisms do, and energy from organic matter is disassembled for energy, and is converted into water and carbon dioxide. From the breathing of these animals, carbon gets released as water and carbon dioxide back into the ecosystem. This carbon dioxide is then reabsorbed by plants and seaweeds, and is used for photosynthesis. Like so, carbon circulates the organic environment and inorganic environment through photosynthesis and respiration. Oxygen is released into the air as a result of photosynthesis by plants and seaweeds. Most of the oxygen on Earth is made by photosynthesis, and as energy can be created effectively from organic matter when oxygen is taken in, most organisms use oxygen for respiration. Oxygen is used by oxygen breathing organisms including plants, animals, fungi, and bacteria, and as a result, it is converted into water, which gets released back into the environment. 213  3. Nitrogen cycle Nitrogen is an important component in forming important material including proteins and DNA that make up the body of organisms, and chlorophyll. Plants (producers) absorb nitrogen compounds from chemicals such as ammonia in the soil as nutrients, and use this to create matter. Consumers absorb the proteins from the plants they eat, and break down its DNA to absorb it, and convert them into proteins and DNA for their body. Fungi and bacteria not only use the proteins and DNA for their body, but also are able to decompose nitrogen compounds and gas to put them back into the soil. Nitrogen that returns to the soil is then reabsorbed by plants to build their body. 214  Like the rhizobium living in symbiosis with the roots of legumes, there are bacteria that take in nitrogen in the air to convert them into nitrogen compounds. Due to these functions in these bacterias, nitrogen in the air is able to go back into the soil as nitrogen compounds, and are able to be part of the food chain. 2. Energy flow All the energy that we use for life is taken in from our food, and these foods can all be traced back to producers. Producers create organic matter using light energy from the sun. Organic matters are energy that capsules that trap light energy using carbon dioxide and water. These energy capsules can be decomposed to eject energy from them, and this is done through respiration. Plants are able to convert light energy into energy that animals can use for life activities, and all organisms use this energy to live. Light energy is stored by organic matter, and all organisms have access to energy due to food chains. As we can see from this, all the energy organisms use can be traced back to light energy from the sun, and are able to flow through the ecosystem. 215  ➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖➖ Coal and oil also originate from solar energy Where do coal and oil (Energy source) that supports our daily life activities originate from? Coals are fossils of tree fern and primitive gymnosperm that grew a long time ago. Though the formation of oil is still unknown, the most common theory is the remains of microorganisms in the ocean being converted through the great pressure and heat underground. For this reason, these are known as fossil fuels. As they are the remains of organisms, they must be made from organic matter made from photosynthesis, and by burning this organic matter, we are able to extract the energy from the organic matter. Meaning, all the energy we use for survival can be traced back to the organic matter made by plants, and therefore is the light energy of the sun from a long time ago. 216  Section 3: Ecosystem conservation As a result of the advancement in civilization, human activity has become more active, and has grown in range, and as a result have a great effect on the ecosystem. As we are part of the ecosystem, this disruption in the ecosystem also has a great effect on us. What might some of the effects of human activity be? 1. Nature conservation and environmental issues 1. Invasive and native species Human activities have intentionally and unintentionally brought species where they do not belong in nature, and these species are known as invasive species. They are also known as naturalised species, and introduced species. In contrast to this, species that belong in a certain region in nature are known as native species. When there isn't any prey in the introduced land for the invasive species, they create an outbreak, and can negatively impact crops, and cause havoc on farms and humans. Moreover, when in competition with the native species, they can decrease the population of the native species, or the invasive species can disappear with the great decrease in its population. Moreover, there are cases where the invasive species and the native species mate, where the DNA unique to the native species disappears. Disruption in the ecosystem and negative impacts on human lives can be seen in Japan as well. For example, the Black bass released for the purpose of lure fishing ate the fish native to the land, and have caused catastrophic damage. Moreover, racoons introduced to Japan for the purpose of being sold as pets became wild animals, and bred, and people are worried it may damage the crops. There are other examples of invasive species including the Nile perch that made more than 200 species of fish extinct, and Louisiana crawfish that were imported as food for the American bullfrog, and many others, and these dangers revolving the introductions of new species still exist today. When looking at the 100 of the world’s worst invasive alien species of the IUCN (International Union for Conservation of Nature), it is clear how so many species have spread across the globe, and we can understand how they impact the ecosystem. Protecting the diversity of species on Earth is important for maintaining our lives. Biological gardens hold self-control systems, and are known for being resilient. 217  However, isolated ecosystems such as islands have few producers, consumers, and decomposers that support the food chain, and are vulnerable to invasive species. In many islands across the globe, species are becoming extinct at a speed faster than it has before. Ogasawara Islands (Japan), registered as a World Heritage Site, is no exception. Recently, to prevent further biodiversity loss, various countries and regions have created a red data book following the guidelines set by the IUCN (IUCN red list). The Nature Conservation Society of Japan, and the “Current status of plants important for protection in Japan(red data book for plants)” published by the World Wildlife Fund Japan in 1989 is part of the Japanese red data list. In 1992, a law on the protection of wild animals in danger of extinction(Act on Conservation of Endangered Species of Wild Fauna and Flora.) was made, and a red data book of vertebrates, invertebrates, vascular plants, and other plants were made by the ministry of the environment, and the fisheries agency created a red data book on the rare wild aquatic life in Japan. Moreover, 24 prefectures from Hokkaido to Okinawa created a red data book, and organisations such the Mammal Society of Japan and the lepidopterological society of japan have made their own red data book. According to the 2018 red data book of the ministry of environment, approximately 21% of mammals, 14% of birds, 37% of reptiles, 38% of amphibians, and 19% of shellfish in Japan are endangered species. 218  Table 9-1 Extinction in Japan, number of endangered species (Ministry of Environment, 2018) Taxon Total number extinc Extinct in Endanger Near Lack of (b/a) of species to t the wild ed Threatene informati be evaluated species(b) d Species on (a) an mammals 160 7 0 33 18 5 20.6% imals etc. birds approx. 700 15 1 97 21 17 13.9% reptiles 100 0 0 37 17 4 37.0% amphibia 76 0 0 29 22 1 38.2% ns Brackish approx. 400 3 1 169 35 37 42.3% water / freshwate r fish insects approx. 4 0 363 350 153 1.1% 32,000 shellfish approx. 3,200 19 0 616 445 89 19.3% other approx. 5,300 0 1 65 42 43 1.2% invertebra tes Animal subtotal 48 3 1,409 950 349 –––––– plant etc. vascular approx. 7,000 28 11 1,786 297 37 25.5% plants bryophyte approx. 1,800 0 0 241 21 21 13.4% s seaweeds approx. 3,000 4 1 116 41 40 3.9% Lichen approx. 1,600 4 0 61 41 46 3.8% fungi* approx. 3,000 26 1 62 21 50 2.1% Plant subtotal 62 13 2,266 421 194 ––– Animal・plant total 110 16 3,675 1,371 543 –– *excluding the species invisible to the naked eye 219  2. Global warming and the ecosystem Global environmental problems have been greatly magnified since the 1980s. Global environmental issues and their damages and effects do not stay in one country, but crosses borders and can expand to Global issues, and some of these examples include global warming, ozone depletion, acid rain, desertification, destruction of tropical forests, decrease in wild species, and Marine pollution. Here, let's focus mainly on global warming. There are gases in the air that hold greenhouse-like properties. The greenhouse effect is the phenomenon where the gas acts as a comforter when heat is released from the ground to the sun, and as a result, partially returns the heat back into the ground. Some examples of greenhouse gases include steam, carbon dioxide, and methane. Of these, steam has the strongest greenhouse effect. If greenhouse gases weren’t to exist in the atmosphere, the average temperature of Earth is estimated to be only -18ºC. In reality, the average temperature of Earth is approximately 15ºC, and is far from the estimated value, and is the result of greenhouse gases. When greenhouse gases increase as a result of human activity, more heat is unable to escape, and is thought to result in global warming. However, the reason global warming is an issue is not because all gases have the property of being greenhouse gases, but because of carbon dioxide. Carbon dioxide is created from the result of burning fossil fuel like coal and oil for factories, nuclear power plants, and vehicles, and is increasing every year. This carbon dioxide is said to be the reason behind the increase in global warming. On the other hand, this greenhouse effect is important for organisms, and therefore we should think about how the types and amount of greenhouse gases are changing, how some gases may increase in the following years, and how we can change our actions to suppress further damages caused by human activity. There are many reasons people predict when it comes to the effect of global warming. As a result of Earth warming at such a rapid speed, plants and animals that cannot adapt to the new climate become extinct, glaciers melt and the sea-level rises, and lands that used to be above sea-level can sink. Abnormal weather occurs across the globe, water and food run short, and there are also concerns that tropical diseases such as malaria will move north along with its mediating insects, killing many humans. 220  Most of all, it is expected that global warming would cause great damage to the ecosystem, and the indications of this being a reality has already been seen. A butterfly known as the Indian Fritillary Circulated in the south of the Chugoku / Shikoku region in the end of the 20th century however, their have now spread in a wider range and in recent years, they can be seen in the north Kanto to the Tohoku region. There is no change in properties such as dormant life and cold resistance, and the distribution of larval food (Violaceae, previously distributed throughout Japan), and as the Indian Fritillary can be seen in regions where the annual temperature and the winter minimum temperature has increased, it can be inferred that this movement is the result of global warming. 221  There are other southern insects known to have moved up north such as the papilio memnon and the black cicada. These migrations to the north can be seen in foreign countries as well. For example, when observing the butterfly distribution across Europe, it can be seen that many species have migrated up north. There has been global warming and cooling on Earth before, and species distribution has been changing accordingly. However, the current rate of global warming is rapid, and organisms unequipped for such movement and dispersion like trees are in danger of extinction. When plants, more importantly producers, get affected by this, there is a concern that the whole ecosystem is in grave danger. 2. Various ecosystems Organisms living in a region are all connected through the food chain, and matter circulates this food chain and the environment surrounding it. Light energy from the sun is the source of all organism activity, and is released into the environment through the food chain. This light energy also affects the environment, that greatly affects organism activity, other than organisms itself such as temperatures, water content, the amount of carbon dioxide, and currents. These environments that surround organisms and the ecosystem include forest, lakes, and oceans, that makes organisms and matter stay at one location and has ecosystems unique to that region. When looking at the larger picture, Earth is one ecosystem. Small things like flower vases and fish tanks have producers, consumers, and decomposes, and inorganic environments, and all of that combined created an ecosystem. Within ecosystems, organism food chains and its surroundings are kept constant. However, when changes occur on earth through things like volcano eruptions and earthquakes, large changes in the climate, human activities, and introduction of invasive species that goes with it can disrupt ecosystems, and cause organisms to go extinct. 222  Section 4: Human life and nature Though we are biologically “humans”, it does not mean we live in nature as it is, as we do not just live and leave offsprings, but because we also do industrial activities. In this way, we are not part of the ecosystem, and are instead looking at ecosystems, and are getting involved in inorganic environment and biological communities, from the outside. Human industrial activities include digging up and burning fossil fuel and therefore producing carbon dioxide, which greatly affects the carbon cycle. We create matter that should not have existed in the natural world, and release it into the environment. As a result of humans affecting the natural world(action), biological communities and humans will be affected by the natural world(reaction). Within that, there are those that have life-threatening effects. Moreover, there have been technological advancements in manipulating living things, and this has given us great hope in advancements in medicine and our eating habits. However, in reality, this includes humans being able to create non-existent organisms, and a wrong use of this will cause an irreversible effect on the biological community. Let's look into the effects and mechanisms human activities may have. 1. Biotechnology 1. Cloned animals Clones are populations of organisms of identical genetic information made from one unfertilized egg. Among asexual reproductions, offspring produced by cell division, budding, and vegetative reproduction, etc. is also a type of cloned organisms. The first successful cloning done on mammals was the sheep “Dolly” in the UK. There are two main ways of cloning mammals. One is shaking the fertilised egg at the 2-cell stage and separating the 2 cells. When the embryo is divided into 2, they both start to develop individually. As it originates from a single egg cell, the resulting offspring of the 2 cells have the same genetic material. The other method is taking the nucleus from an unfertilized egg, and replacing it with a nucleus of a somatic cell with the desired traits. In this case, the egg cell and the fertilised egg will start developing simultaneously. As individuals created in this process would only have the transplanted nucleus, the original individual and the individual with the transplanted nucleus would be clones. Dolly was created through this method. Though both methods use nuclei with totipotency (having the ability to differentiate into all types of cells), experimentation on humans is prohibited. 223  2. Callus In newborn cells, there is a state before differentiation. When this starts to form specific shapes and functions, it means it has been differentiated. Differentiated cells form tissues. In plants, differentiation is often triggered by and is regulated by hormones. If we can reverse cells back into the undifferentiated state(dedifferentiate), and are able to use concentrated hormones, we will be able to create issues with different shapes and functions, and therefore will be able to create a completely different type of tissue(redifferentiate). For example, the carrot we eat is the root part of the plant; however, if we are able to take out the part with the cambium, and multiply, we will be able to create tissues that do not resemble the original clod. This clod is known as the callus (cell mass), and as calluses have the ability to be totipotent, by adjusting the plant hormone concentration, we will be able to redifferentiate it as roots, leaves, and stems. 3. Protoplast Protoplasts are plant cells with its cell wall removed with an enzyme known as the cellulase. When putting this into a polyethylene glycol solution (PEG), the 2 cells attract one another, and merge, and become 1 cell. This cell eventually forms a cell wall, and turns into a callus, and turns into an individual through multiplying. Here, when taking in plant cells from 2 different species, the new individual will be a hybrid. For example, the hybrid of chinese cabbages and red cabbages are Hakulan. There have been experiments in making an orange and karatachi orange hybrid known as “oretachi”. These technologies have been used for agriculture and breeding, and there are things like grafting that uses calluses and protoplasts. 4. Gene modification E. coli do not have luminescent characteristics, however, by extracting the DNA with the luminescent function from a bioluminescent organism, and putting it in, the E. coli is able to have that function. The first genetically modified product that was commercialised was the “super flavour tomato” in America, in 1994 and it was genetically modified so that it was able to stay fresh for days. Blue carnations, that do not exist in nature, are made by using the blue pigment from petunias. Organisms are often genetically modified to make them genetically stronger to insects and to make them more resistant to viruses. However, through these genetical modifications, there may be dangers of pesticides being ineffective, and having effects on humans from consuming them, and therefore have strict regulations and restrictions on these genetical modifications. 224  5. Gene Therapy Through gene modification, there are some that can inhibit the progression of diseases. Specifically, there is a method in curing disease, where gene modifications are utilized.However, the treatment will include a lot of procedures and examinations, as the manipulation in the genetics will result in the body working in a way that shouldn’t have in the person originally. Moreover, through investigation of the genes, people can find out the diseases they are more prone to have, and therefore have been used for prenatal diagnosis. More importantly, if they are diseases with severe symptoms, they may be able to be prepared for them. In addition, by investigating the genes, there are high hopes in finding effective medications. These researches are going on regarding gene diagnoses, and gene prescriptions however, there are many challenges we must overcome, including investigations on individual genes and treatments, and the mental distress that comes with it. 2. Conservation of the natural environment 1. Global warming If greenhouse gases cover the Earth, it gets harder for the infra-red rays that enter the Earth to leave. As the infra-red rays are the sources of heat, if they stay on Earth, heat accumulates even at night, and makes it easier for the temperature to rise. These greenhouse gases include gases that easily combusts such as carbon dioxide, methane, and nitrous oxide, and those that are used in the manufacturing process of factory products such as freon, and sulphur hexafluoride. When the average temperature increases by 2ºC, the climate changes to that of approximately 500 km closer to the equator. Meaning, the Kyushu and the Pacific coast of Honshu will have a subtropical climate. This will not only affect agriculture, but will also mean the invasion of southern disease carrying insects and therefore the antigens, and there have already been cases of a species of malaria-borne Anopheles mosquitoes confirmed. 2. Ozone hole The ozone layer forms 20000 m high in the atmosphere. An ozone atom is 3 oxygen atoms combined together, and is made by the ultraviolet rays hitting 2 oxygen atoms. Though cells break down and genetic information can get damaged when ultraviolet rays hit cells at great strength, there are organisms that live on land for the purpose of absorbing the ultraviolet rays of the ozone layer. However, specific gases like freon have the ability to disassemble ozone molecules like a chain reaction. Because of this, when these gases are released continuously, they can thin out the ozone layer and create ozone holes. 225  3. Acid rain/Acid fog Rains with a pH less than or equal to 5.6 are known as acid rains, and those in a mist form are known as acid fogs. These emit sulphur oxides ( SOx ), and nitrogen oxides (NOx) into the air by burning matter that has sulphur and nitrogen, and creates acid rain and fogs by dissolving into moisture. 4. Endocrine disruptor Endocrine disruptors are artificial chemicals similar to hormones responsible for biological functions in the animal body. When endocrine disruptors enter the body, it can cause great damage such as disrupting what the hormone would do in nature, or causing the body to go through the opposing reaction. From these characteristics, they are sometimes referred to as environmental hormones. Artificial objects that do not exist in nature and have a particularly large impact are set as POPs in international treaties, where each country individually sets restrictions by law. 226  Table 9-2 POPs set by the POPs treaty (Persistent organic pollutants) name of substance main statements in the name of substance main past statements in the past Polychlorinated Insulation oil for Linden Pesticides biphenyl(PCB) storage of electricity, etc. Aldrin Pesticides, etc. α-Hexachlorobenzene By-products of Linden production, etc. DDT Pesticides, pest control ß-Hexachlorobenzene By-products of Linden agents, etc. production, etc. Endrin Pesticides, etc. Polybromo Diphenyl ethers Flame retardants made of plastic resin, etc. Dieldrin Pesticides, pesticides Tetrabromodiphenyl ethers etc. Chlordane Pesticides, pest control Pentabromodiphenyl ethers agents, etc. Heptachlor Pesticides, pest control Hexabromodiphenyl ethers agents, etc. Kepone Pest control Heptabromodiphenyl ether agents(overseas) Toxaphene Pesticides (overseas) Hexabromodiphenyl Retardants made of plastic resin(overseas), etc. Mirex Pesticides (overseas) Perfluorooctane sulfone Antireflection agents for semiconductors, etc. Hexachlorobenzene (HCB) Raw materials for Dioxins Created when things herbicides, etc. are burned Pentachlorobenzene Pesticides (overseas), Endosulfan Pesticides, etc. (PeCB) Pesticide impurities 227  5. Bioconcentration Disposed and scattered artificial matter can take a very long time to break down in nature, or not break down in nature at all. Of these substances , those that do not get discharged easily once it enters a body, and through the food chain, it accumulates on organisms at the higher trophic levels. This is known as bioconcentration. Organic mercury that caused the Minamata disease was only thought of as being taken in from marine animals however, as those at higher trophic levels directly eat them or eat the mercury accumulated in the body of lower trophic organisms, as a result, the concentration got higher in the order of plankton → small fish→ large fish→ marine birds→ mammals. 6. Specific invasive species Specific invasive species are plants and animals that flourished in places after being introduced to a land through human activities, distribution, and storms. Within specific invasive species, there are cases where they preyed on the native species, or have changed vegetation. In Japan, some issues regarding this are the Black bass, the bluegill, and the red-eared slider. These organisms are greatly restricted in movement and breeding, and are exterminated for the reason of them being specific invasive species. 7. Endangered Species It is said that approximately 100 species of plants and animals are going extinct every day. A reason behind this includes natural causes, but also industrial activities. For this reason, the IUCN(International Union for Conservation of Nature) created a “Red data book” where endangered species are listed, and people started to think about the protection of these species and restrictions in human activities. This thing that maintenances this is known as the Washington Convention, and movements and transactions are restricted through CITES Ⅰ~Ⅲ. Moreover, recently, through the “Convention on Biological Diversity”, each country started to cooperate for the protection of the natural environment. 228  ----------------------------------------------------------------------------------------------------------------------------- Chapter Exercise ----------------------------------------------------------------------------------------------------------------------------- 1. Regarding the natural world, organisms are connected by the food chain through their “prey→predator” relationship. Answer the following regarding these connections. ① What is this connection called? ② In this connection, what are organisms that undergo photosynthesis called? ③ In this connection, what are organisms that prey on plants and other animals called? ④ From the following A~D, which of the following connections are wrong? A. Rice → locusts → frog B. Fallen leaves → earthworms → moles C. Daphnia pulex → shark → tuna D. Diatom → Daphnia → Medaka 2. The image on the right represents an ecological pyramid in a forest. ① What kind of animals fit into A? ② Of A~C, what does the volume of each block represent? ③ In a forest, let's say that organisms belonging to block B were to decrease in population all of a sudden for some unknown reason. In this situation, how will the population of A and C change? Of the words “decrease” and “increase”, which word will fit into the blanks ⓐ ~ⓓ Due to the decrease of B, A will ( ⓐ ), and C will ( ⓑ ). Eventually, from reasons such as the ( ⓐ ) of A, B will ( ⓒ ), and C will ( ⓓ ) and the balance will be kept. 3. The image on the right represents the circulation of Carbon in the natural world. Answer the following. ① What is the substance name of gas X? ② Of arrows a~e, what is the name of the function that allows the carbon to move for each organism? ③ In the image, what is organism D called from the function it does in the natural world? 229