Ecology PDF
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EECCOOLLOOGGYY BBrriittaannnniiccaa IIlllluussttrraatteedd SScciieennccee LLiibbrraarryy Encyclopædia Britannica, Inc. Chicago ■ London ■ New Delhi ■ Paris ■ Seoul ■ Sydney ■ Taipei ■ Tokyo BBrriittaannnniiccaa IIlllluussttrraatteedd SScciieennccee LLiibbrraarryy © 2013 Editorial Sol 90 All rights reserved. Idea and Concept of This Work: Editorial Sol 90 General Director: Fabián Cassan Project Management: Carolina Berdiñas Photo Credits: Comstock/Jupiterimages, Corbis, Getty Images Composition and Pre-press Services: Editorial Sol 90 Translation Services and Index: Publication Services, Inc. Portions © 2013 Encyclopædia Britannica, Inc. Encyclopædia Britannica, Inc. Encyclopædia Britannica, Britannica, and the thistle logo are registered trademarks of Encyclopædia Britannica, Inc. Jacob E. Safra, Chairman of the Board Britannica Illustrated Science Library Staff Jorge Aguilar-Cauz, President Editorial Michael Ross, Senior Vice President, Product Development, Michael Levy, Executive Editor, Core Editorial and Education GM John Rafferty, Associate Editor, Earth Sciences William L. Hosch, Associate Editor, Mathematics and Dale H. Hoiberg, Senior Vice President and Editor Computers Kara Rogers, Associate Editor, Life Sciences Marsha Mackenzie, Executive Director, Media and Production Rob Curley, Senior Editor, Science and Technology David Hayes, Special Projects Editor Art and Composition Steven N. Kapusta, Director Carol A. Gaines, Composition Supervisor International Standard Book Number (e-book set): Christine McCabe, Senior Illustrator 978-1-61535-819-9 International Standard Book Number (e-book volume): Media Acquisition 978-1-61535-836-6 Kathy Nakamura, Manager Britannica Illustrated Science Library: Ecology 2013 Copy Department Sylvia Wallace, Director Julian Ronning, Supervisor Information Management and Retrieval Sheila Vasich, Information Architect Production Control Marilyn L. Barton Manufacturing Kim Gerber, Director www.britannica.com (cid:60)(cid:90)(cid:102)(cid:99)(cid:102)(cid:94)(cid:112) Contents PHOTOGRAPH ON PAGE 1: The water is stained a deep red from iron ore washing at a mine in Michigan. Ecology: Introduction and Background Page 6 Studying Nature Page 16 Major Biomes of the World Page 28 Life in the Water Page 66 Humans and the Biosphere Page 82 The Oldest This unique science was so complex and species that compete with one another for encompassing that it was not until the the same resource. This exploration will also 19th century that its scientific reveal surprising relationships in which Science . . . and foundations could be laid, formal study could species mutually benefit from one another. begin, and the word “ecology” could come into existence. This book serves as a detailed We will then be ready to understand the Most Recent introduction to the subject. how nonliving, physical environments influence, modify, We will begin by learning what and even determine the characteristics of ecology is and what it is not. (At this complex bundle of interactions. At this times the word has been used moment, we will define the word Long ago when people still lived in WHEAT HARVEST incorrectly as a synonym for environmental “ecosystem” and learn how materials and A productive soil is much more caves—perhaps at the same time when than “dirt.” Farmers know that to protection.) Later, we will look at how living energy pass through its living and nonliving produce a good crop it is they developed habits that were important to maintain the things are classified, before moving into the parts. These concepts are needed for the ecological balance of the soil. different from those of other animals— study of the environments in which they live: next step, the examination of each of the humans began to practice ecology. They the land, water, and air. world’s major biomes. We will examine both became keen observers of nature through terrestrial and aquatic biomes and the such basic and instinctive actions as tracking The next stop along this journey, filled characteristic plant and animal species both large wild animals and small prey, with exciting information and found within them, including those species discerning edible plants from poisonous ones, marvelous illustrations, will be devoted that may be in danger of extinction. Finally, and noting the time of year when different to ordering and organizing the surprising we will look at the place that people occupy plants could be gathered. From necessity and diversity of living organisms on Earth. Living in the biosphere—the ways in which their inherent curiosity, humans began to learn things are first grouped into populations activities change nature and even create about the relationships between living things according to their kinship, then into new ecosystems. In the urban centers, and the environment. As the field of ecology communities according to the spaces they different species have developed novel grew, its focus went beyond the simple share. The exploration into the ways in strategies to cope with the challenges of cataloging of living things in the world. which organisms interact will show that life in the “concrete jungle.” Despite the Ecologists also became interested in some interactions can be very cruel, such as damage to the environment caused by understanding how living things function those between predators and prey or those human beings, there is a ray of hope: human and how they interrelate with one another between different ingenuity can also be used to protect the and with the environment—to explain environment and to reduce the harm that peculiar element that makes the caused by their activities. Earth unique: life. Ecology: Introduction WATERWAYS WHAT IS ECOLOGY? 8-9 Can everyday life be imagined without water? Environmentalists say that in the THE FIVE KINGDOMS 10-11 and Background not-too-distant future it may be necessary to confront this possibility, given that THE SOIL 12-13 stocks of usable water are declining. WATER AND AIR 14-15 A ny landscape, from an arid to be busy with some task. How can we monumental task. As a first step, we will classify living things into five major desert to a rainforest, conceals understand what takes place in the investigate the various media in which life kingdoms, which in general correspond an astonishing diversity of environment? How can we determine the occurs—water, land, and air. (Air is as to animals, plants, fungi, prokaryotes, organisms in action. Each mechanisms that govern the actions of important as land and water, even though and protists. Turn the page to begin your appears to play a role and seems living things? Understanding ecology is a it is much less populated.) Then we will exploration into the world of ecology. 8 ECOLOGY: INTRODUCTION AND BACKGROUND ECOLOGY What Is Ecology? The Flow of Energy Distribution In studying ecosystems, it is extremely important Environmental factors (such as climate, geography, to determine the way in which energy is transferred and soil composition) determine the distribution of from organism to organism. species in different biomes. Some branches of biology, such as zoology and botany, are dedicated to the study of living things. Other sciences, such as geology and meteorology, deal with the nonliving parts of the Deserts of ice are among the biomes having the poorest biodiversity. Some of the adaptations of the environment. These nonliving parts include the composition of the Earth, weather phenomena, and organisms that live there, however, are surprising. volcanoes. Ecology, however, takes a little from each of these sciences and looks at the interactions among organisms in a community and between the community and the environment. In this way, Energy from the ecology seeks to explain biodiversity, the distribution of species, and the way ecosystems function. Sun is taken in by plants and passed It also endeavors to foresee the consequences that might result from future changes. along to the deer that eat the plants. It eventually reaches the lion, which preys 40,000 on the deer. Levels of Organization To help understand the complexity of life, ecologists The number of plant recognize different levels of organization. species known in the 19th century. About 500,000 A group of individuals of the same species in a given 25 are known today. location constitutes a population. The populations of different organisms that share an area and occupy it at the same time make up a community. The community, The approximate number in contact with the nonliving parts of the environment, forms an ecosystem. All ecosystems taken together of chemical elements (out comprise the biosphere. of a total of 92 natural elements) that are used by living things. E R INDIVIDUALPOPULATIONCOMMUNITY ECOSYSTEM HE P S O I B Relationships Biodiversity Recycling Milestones in Ecology Ecology places a special emphasis on the The total number of species of living Like energy, nutrients and other Although ecology is usually thought of as one of the newest branches of science, it is complex relationships that living things things that inhabit the planet is substances pass through the also one of the oldest. From the time they were nomadic hunters, people had to be establish within their own species (intraspecific unknown. The variety of ways in which they living organisms in an ecosystem. In concerned about the relationships between living things. relationships) and between different species in a live, however, never ceases to amaze. This this case, substances are used over and community (interspecific relationships). diversity can play an important role in the over, creating a cycle. 4th Century BC19th Century AD1866192619351979 stability of ecosystems. The ants in the The leafy sea dragon (Phycodurus Earthworms, roundworms, bacteria, and photograph hunt eques), an exotic relative of sea fungi make up a group of organisms known Aristotle and his Naturalists embark on great Ernst Haeckel coins Vladimir Vernadsky Arthur Tansley coins the James Lovelock together (an horses, essentially disappears as it as decomposers. They feed on waste disciple Theophrastus maritime expeditions. the term “ecology” publishes The Biosphere. term “ecosystem” to refer publishes Gaia: intraspecific approaches algae; it is hidden by its products and on the remains of dead plants produce the first Humboldt describes the (oekologie, in In this book he de- to the interaction between A New Vision relationship) and perfect camouflage. and animals. They return nutrients back to writings about the relationship between living German) and scribes the concept of biocenosis (a group of About Life on Earth. can therefore the soil, where they are reused by plants. relationships organisms and climate for consequently lends the biosphere and dis- living beings) and the The author argues that capture prey that between organisms. the first time. recognition to the cusses the principal biotope (the environment the living and nonliving are much larger Möbius proposes the term new discipline. biogeochemical cycles. in which they live). elements of the planet than any one of the biocenosis to refer to the interact to form a ants. The concept that the various unique organism that relationship between species in a community are regulates itself to the ants and the not independent of one maintain conditions that worm (predation) another. Darwin publishes his are favorable to life. is interspecific. theory of evolution in On the Origin of Species. Warming lays the foundation for a new discipline when he includes a consideration of abiotic (nonliving) factors in the study of communities. 10 ECOLOGY: INTRODUCTION AND BACKGROUND ECOLOGY 11 The Five Kingdoms 1.5 million 3 PROTISTA (PROTIST) Hierarchical Order Unicellular and multicellular eukaryotic organisms that are Organisms are classified into a system in which some not part of any other kingdom of life. They include I The number of species that have euglenoids, dinoflagellates, fungi, and other eukaryotic groups are placed within larger groups. For example, n order to begin to understand nature, a system must be created to organize the seemingly endless been described by science. It might microorganisms. (In a eukaryote, the cell’s genetic domains are divided into kingdoms, which in turn are divided represent only 5% of all the species material is organized into into phyla. Phyla are divided into subphyla and so forth array of organisms. This issue, which has been the topic of many proposals, debates, and disputes in the world. chromosomes, and a down to the level of species. nuclear membrane among naturalists for centuries, has yet to be completely resolved. Nevertheless, a few methods for separates it An Example: The Classification classifying organisms have been established that pay attention to the morphological characteristics from the rest of the cell.) of Human Beings (or physical features) of different groups and their evolutionary history. Both classification methods Paramecium Domain: Eukarya (organisms whose are used to determine the relationships between organisms. 2 PLANTAE (PLANTS) sonneborni cells contain linear DNA, a Magnified cytoskeleton, a nuclear Multicellular organisms. Their cells 1,500 times. membrane, and other are eukaryotic, and they have a internal membranes). cell wall. Using a pigment called Universal Names Classifying Life chlorophyll, they capture energy Homo from sunlight and use it to Kingdom: Animalia (multicellular neanderthalensis produce and store their food. organisms that ingest There are two types of names for organisms. The At one time, all living things their food). common name is the one most people use, but common were formally classified into names can vary from one region to another. The scientific two kingdoms, animal and plant. 4 PROKARYOTA (PROKARYOTE) Phylum: Chordata (animals that name, derived from Latin, allows any researcher in the world Today the most widely accepted at some time in their life Unicellular organisms. They are cycle have a hollow to refer to a specific organism without the possibility of classification divides organisms prokaryotes—that is, they have relatively dorsal nerve cord and confusing one species with another. into five kingdoms, although a few primitive cells. In prokaryotes, genetic pharyngeal gill slits). alternative systems have been material is not surrounded by a nuclear proposed and are under discussion. membrane (as it is in eukaryotes); it is Subphylum: Vertebrata (animals that instead inside a cytoplasmic compartment. have a nerve cord enclosed Homo erectus The scientific name in a vertebral column). of the great white shark is Superclass: Tetrapoda (land animals Carcharodon with four limbs). carcharias. 1 ANIMALIA (ANIMALS) Class: Mammalia (the young are nourished with milk from Multicellular mammary glands; the skin organisms. Their cells has fur; they are are eukaryotic and do warm-blooded). Homo sapiens Amazon river not have a cell wall. dolphin, pink dolphin, In general, they are Order: Primates (they have fingers and flat nails, a poor cboomtom, aonnd n baumfeeos agriveen athbeleir toow mno pvoew uenrd.er Colony of Escherichia coli saenncsees toofr ss mdiedl)l,. and arboreal habits—or at least their Each bacterium is about 100 times to a single animal: smaller than the thickness of a human Inia geoffrensis. Family: Hominidae (bipedal and flat faced, with frontal hair. These bacteria cause various vision and color vision). human diseases, such as salmonella. Genus: Homo (communicates by means of a language). Above, the skulls of three species of the genus Homo are shown. 5 FUNGI (FUNGUS) Species: Homo sapiens (have a prominent chin, little body hair, and a high forehead). Eukaryotic organisms. Traditionally, fungi were included in the plant kingdom, but they now constitute their own group. A NEW CLASSIFICATION One of their characteristics is that they form spores. Their cellular structure is The best way of classifying organisms continues to be debated. A very different from that of plants. new category that has been proposed—the domain—lies above the level of kingdoms. According to this classification scheme, there BINOMIAL NOMENCLATURE are three domains (two for prokaryotes and one for eukaryotes), which in turn are divided into kingdoms. By convention, scientific names are generally Latin words; they are written in italics. Determining Kinship Inia geoffrensis Through the study of evolution, it is possible to determine the relatedness and common ancestry of The first word is the The second word organisms that look very different. genus, and its initial is a qualifier, and together letter is always with the first word it capitalized. indicates the species. Homologous Analogous Structures Structures 34 They can be equivalent structures Although these structures (such as the wings of a bat and appear to be similar or equivalent, the wings of a bird) or different a careful analysis will show that The arm of a human being The wing of a bird and that of an insect, in contrast, The approximate number of phyla into which the structures (such as the wing of a they have independent origins (such and the wing of a bird are homologous are analogous structures. They do not have a animal kingdom is divided. The mollusk phylum bird and the arm of a human). as the wing of a bird and the wing structures. Even though they are different, common origin; however, each represents a similar alone (which includes snails, octopuses, and Nevertheless, they have a of an insect). They are simply the they have a common origin. adaptive strategy—in this case the ability to fly. common origin and thus denote result of similar adaptations by clams) has about 90,000 species. a degree of kinship. organisms to a given environment. Although they are different, birds and humans are more closely related than birds and insects. 12 ECOLOGY: INTRODUCTION AND BACKGROUND ECOLOGY 13 The Soil Properties 170 A Because of their nature, soils have a variety of physical and TEXTURE ny study about nature needs to consider the importance of soil. Soil provides the surface upon chemical properties. The following are the most important: The number of colors in Using a magnifying glass or microscope, it is possible to see that the which soils can appear. which terrestrial organisms carry out their existence, and it is typically the first and foremost COLOR soil is made up of countless particles of various sizes. This characteristic source of nutrients in an ecosystem. Not all soils are the same, however, nor do they One of the most useful and readily apparent properties for icsa epxatcrietym feolyr aimerpaotriotann, ta nbde citasu saeb iiltit dye ttoe rhmolidn ews attheer .soil’s porosity, its 100 have the same properties. An effort toward understanding the soil will yield identifying soil classes is their color. Soil particles are classified by size. This triangular table 90 10 surprising details about the world that exists under our feet. Black can be used to identify Black soil is generally associated soil textures according 80 20 500 with a high content of organic Sand to the soil’s physical One Name, Many Horizons years mIna gteerniearl aaln idt ihsa vse gryo ofder sttilreu.cture. composition. 6070 Clay 3040Percenta pina sitssa fgtBoeher emolo fsaw tttri imutohcneet—.u sTrmuoerg,i fnceaeotchrmeae lpor ,tof y tsthpihteeieo s s,ng oc,ri lolai muhnnodadr tti,ez ht,oi hconekrs gn sleaioesni lsiu s iposm foo snwr tgshhaoiancltihid zl eidrvdoee pc inikent n (oidbt ,le oadaynnre odmrc satk h(n)h.eyo fraizcotnosr)s, Ttfeohr efto itlreimm s eoa i rll ea1qy iuenircr heod f oRRwmxeeioitdddihs es twsou.i ralIe rti sm ai snt ycdupl isimisuc aaalolltllweyys ar iwinscs hifote hcirn itla oiitlrwieotdyn. Percentage of cla3y04050SSlcoacalanlanamdydyyy lColaamy ScillaSctyyillatyy506g0e o7f s0ilt (2.4 cm) thick. 20 Loam 80 Silt Sandy Silt Loamy loam 10 loam 90 sand 1 A Horizon Sand Silt Yellow 90 80 70 60 50 40 30 20 10 This is the top layer of soil, where humus accumulates. Humus is formed from organic Yellow soil tends to have Percentage of sand average or low fertility. material mixed with the mineral components of the soil, and it supports a rich variety of Humus Water Air microscopic organisms. When it rains, water An average volume of soil is 25% 25% dissolves some of the components of the A primarily composed of mineral horizon and carries them into the layer below. particles, air, and water and is Brown Clay only 5% organic material. Brown soil has little organic 2 B Horizon material, and its fertility Organic material 5% is variable. This layer has more clay and is rich in Composed of minerals, especially iron oxides and lime. Organisms 10% It receives material from both the A Each horizon horizon and the C horizon. can be divided White Roots 10% into layers and White soil is associated with Humus 80% Mineral subhorizons, particles light-colored minerals (such as depending on 45% 3 C Horizon calcite, gypsum, silicates, and the soil’s salts). It sometimes indicates ACIDITY Although its characteristics are similar particular soil removal. to the B horizon, this layer contains characteristics. The acidity or alkalinity of the soil is another extremely important characteristic. It is measured chemically. fragments of bedrock that have not been weathered like those in the B horizon. Gray 0 7 14 A gray soil is likely one that Acid Neutral Alkaline was saturated with water and in 4 R Horizon which there was bacterial Soils with a pH of 7 are neutral. Those with a pH less than 7 are acidic, and those with a pH greater than 7 are activity in the absence of oxygen. alkaline. Typically, agricultural soils are slightly acidic, with a pH between 5.5 and 6.5. Also known as bedrock, or consolidated rock, it is the solid layer upon which the rest of the soil rests. It slowly contributes mineral material to the layers above it. Arthropods From Rock to Soil Arthropods Nematodes The formation of the soil is a long process that normally takes thousands of Miniature Universe years. Some soils in India, Africa, and Australia are more than two million Birds years old. The process begins with the interaction between the atmosphere and In the soil—within the humus and solid rock; then a biological component is added. among the remains of dead plants Plants and animals—there exists a universe of Nematodes SUNSHINE RAIN HUMUS microorganisms that take care of decomposing these materials into simple Fungi organic compounds and returning them Mammals to the soil. Nematodes one billion Bacteria Protozoa Organic material 1 Solid rock exposed to the atmosphere 2 Organic material filters into the cracks 3 Organic material, together with minerals 4 The soil has formed and begins to begins to weather and erode. and helps disintegrate the rock. from the rock, begin to form a layer of develop further. The growth of The number of microorganisms that can live First Second Third Fourth Fifth humus. The soil horizons become defined. vegetation deepens the humus layer. in 35 cubic feet (1 cubic meter) of fertile soil. trophic level trophic level trophic level trophic level trophic level
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