The Ecology Book Read online

  CONTENTS

  HOW TO USE THIS EBOOK

  INTRODUCTION

  THE STORY OF EVOLUTION Time is insignificant and never a difficulty for nature • Early theories of evolution

  A world previous to ours, destroyed by catastrophe • Extinction and change

  No vestige of a beginning—no prospect of an end • Uniformitarianism

  The struggle for existence • Evolution by natural selection

  Human beings are ultimately nothing but carriers for genes • The rules of heredity

  We’ve discovered the secret of life • The role of DNA

  Genes are selfish molecules • The selfish gene

  ECOLOGICAL PROCESSES Lessons from mathematical theory on the struggle for life • Predator–prey equations

  Existence is determined by a slender thread of circumstances • Ecological niches

  Complete competitors cannot coexist • Competitive exclusion principle

  Poor field experiments can be worse than useless • Field experiments

  More nectar means more ants and more ants mean more nectar • Mutualisms

  Whelks are like little wolves in slow motion • Keystone species

  The fitness of a foraging animal depends on its efficiency • Optimal foraging theory

  Parasites and pathogens control populations like predators • Ecological epidemiology

  Why don’t penguins’ feet freeze? • Ecophysiology

  All life is chemical • Ecological stoichiometry

  Fear itself is powerful • Nonconsumptive effects of predators on their prey

  ORDERING THE NATURAL WORLD In all things of nature there is something of the marvelous • Classification of living things

  By the help of microscopes nothing escapes our inquiry • The microbiological environment

  If you do not know the names of things, the knowledge of them is lost • A system for identifying all nature’s organisms

  “Reproductively isolated” are the key words • Biological species concept

  Organisms clearly cluster into several primary kingdoms • A modern view of diversity

  Save the biosphere and you may save the world • Human activity and biodiversity

  We are in the opening phase of a mass extinction • Biodiversity hotspots

  THE VARIETY OF LIFE It is the microbes that will have the last word • Microbiology

  Certain tree species have a symbiosis with fungi • The ubiquity of mycorrhizae

  Food is the burning question • Animal ecology

  Birds lay the number of eggs that produce the optimum number of offspring • Clutch control

  The bond with a true dog is as lasting as the ties of this earth can ever be • Animal behavior

  Redefine “tool”, redefine “man”, or accept chimpanzees as humans • Using animal models to understand human behavior

  All bodily activity depends on temperature • Thermoregulation in insects

  ECOSYSTEMS Every distinct part of nature’s works is necessary for the support of the rest • The food chain

  All organisms are potential sources of food for other organisms • The ecosystem

  Life is supported by a vast network of processes • Energy flow through ecosystems

  The world is green • Trophic cascades

  Islands are ecological systems • Island biogeography

  It is the constancy of numbers that matters • Ecological resilience

  Populations are subjected to unpredictable forces • The neutral theory of biodiversity

  Only a community of researchers has a chance of revealing the complex whole • Big ecology

  The best strategy depends on what others are doing • Evolutionarily stable state

  Species maintain the functioning and stability of ecosystems • Biodiversity and ecosystem function

  ORGANISMS IN A CHANGING ENVIRONMENT The philosophical study of nature connects the present with the past • The distribution of species over space and time

  The virtual increase of the population is limited by the fertility of the country • The Verhulst equation

  The first requisite is a thorough knowledge of the natural order • Organisms and their environment

  Plants live on a different timescale • The foundations of plant ecology

  The causes of differences among plants • Climate and vegetation

  I have great faith in a seed • Ecological succession

  The community arises, grows, matures, and dies • Climax community

  An association is not an organism but a coincidence • Open community theory

  A group of species that exploit their environment in a similar way • The ecological guild

  The citizen network depends on volunteers • Citizen science

  Population dynamics become chaotic when the rate of reproduction soars • Chaotic population change

  To visualize the big picture, take a distant view • Macroecology

  A population of populations • Metapopulations

  Organisms change and construct the world in which they live • Niche construction

  Local communities that exchange colonists • Metacommunities

  THE LIVING EARTH The glacier was God’s great plow • Ancient ice ages

  There is nothing on the map to mark the boundary line • Biogeography

  Global warming isn’t a prediction. It is happening • Global warming

  Living matter is the most powerful geological force • The biosphere

  The system of nature • Biomes

  We take nature’s services for granted because we don’t pay for them • A holistic view of Earth

  Plate tectonics is not all havoc and destruction • Moving continents and evolution

  Life changes Earth to its own purposes • The Gaia hypothesis

  65 million years ago something killed half of all the life on the Earth • Mass extinctions

  Burning all fuel reserves will initiate the runaway greenhouse • Environmental feedback loops

  THE HUMAN FACTOR Environmental pollution is an incurable disease • Pollution

  God cannot save these trees from fools • Endangered habitats

  We are seeing the beginnings of a rapidly changing planet • The Keeling Curve

  The chemical barrage has been hurled against the fabric of life • The legacy of pesticides

  A long journey from discovery to political action • Acid rain

  A finite world can support only a finite population • Overpopulation

  Dark skies are now blotted out • Light pollution

  I am fighting for humanity • Deforestation

  The hole in the ozone layer is a kind of skywriting • Ozone depletion

  We needed a mandate for change • Depletion of natural resources

  Bigger and bigger boats chasing smaller and fewer fish • Overfishing

  The introduction of a few rabbits could do little harm • Invasive species

  As temperatures increase, the delicately balanced system falls into disarray • Spring creep

  One of the main threats to biodiversity is infectious diseases • Amphibian viruses

  Imagine trying to build a house while someone keeps stealing your bricks • Ocean acidification

  The environmental damage of urban sprawl cannot be ignored • Urban sprawl

  Our oceans are turning into a plastic soup • A plastic wasteland

  Water is a public trust and a human right • The water crisis

  ENVIRONMENTALISM AND CONSERVATION The dominion of man over nature rests only on knowledge • Humankind’s dominance over nature

  Nature is a great economist • The peaceful coexistence of humankind and nature

  In wildness is the preser
vation of the world • Romanticism, conservation, and ecology

  Man everywhere is a disturbing agent • Human devastation of Earth

  Solar energy is both without limit and without cost • Renewable energy

  The time has come for science to busy itself with the Earth itself • Environmental ethics

  Think globally, act locally • The Green Movement

  The consequences of today’s actions on tomorrow’s world • Man and the Biosphere Programme

  Predicting a population’s size and its chances of extinction • Population viability analysis

  Climate change is happening here. It is happening now • Halting climate change

  The capacity to sustain the world’s population • Sustainable Biosphere Initiative

  We are playing dice with the natural environment • The economic impact of climate change

  Monocultures and monopolies are destroying the harvest of seed • Seed diversity

  Natural ecosystems and their species help sustain and fulfill human life • Ecosystem services

  We are living on this planet as though we have another one to go to • Waste disposal

  DIRECTORY

  GLOSSARY

  CONTRIBUTORS

  QUOTE ATTRIBUTIONS

  ACKNOWLEDGMENTS

  COPYRIGHT

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  FOREWORD

  As a small child, I was fascinated by nature—birds, butterflies, plants, reptiles, fossils, rivers, weather, and much else. My youthful passions set me on the path to being a life-long naturalist, and to working as an environmentalist, studying the natural world and promoting action for its conservation. I have worked as a field ornithologist, writer, campaigner, policy advocate, and environmental advisor. All of these diverse interests and activities have, however, been linked by a single theme: ecology.

  Ecology is a vast subject, embracing the many disciplines needed to understand the relationships that exist between different living things, and the physical worlds of air, water, and rock within which they are embedded. From the study of soil microorganisms to the role of pollinators, and from research into the water cycle to investigating Earth’s climate system, ecology involves many specialist areas. It also unites many strands of science, including zoology, botany, mathematics, chemistry, and physics, as well as some aspects of social science—especially economics—while at the same time raising profound philosophical and ethical questions.

  Because of the fundamental ways in which the human world depends on healthy natural systems, some of the most important political issues of our age are ecological ones. They include climate change, the effects of ecosystem damage, the disappearance of wildlife, and the depletion of resources, including fish stocks, freshwater, and soils. All these ecological changes have implications for people and are increasingly pressing.

  Considering the huge importance of ecology for our modern world, and the many threads of thought and ideas that must be woven to gain an understanding of the subject, I am delighted that Dorling Kindersley decided to produce The Ecology Book, setting out the key concepts that have helped shape our understanding of how Earth’s incredible natural systems function. In the pages that follow readers will also discover something about the history of ecological concepts, the leading thinkers, and the different perspectives from which they approached the questions they sought to answer.

  One thing that sets this book apart is the manner in which the rich, memorable, and attractive content is presented. A huge body of information and insight is effectively conveyed by clear layout, graphics, illustrations, and quotes, enabling readers to quickly achieve an understanding of many important ecological ideas and the people behind them: James Lovelock’s Gaia Hypothesis, Norman Myers’s warnings about impending mass extinction, and Rachel Carson’s work to expose the effects of toxic pesticides among them.

  The diverse body of information found in the pages that follow could not be more important. For while the headlines and popular debate suggest it is politics, technology, and economics that are the vital forces shaping our common future, it is in the end ecology that is the most important context determining societies’ prospects, and indeed the future of civilization itself.

  I hope you find The Ecology Book to be an enlightening overview of what is not only the most important subject, but also the most interesting.

  Tony Juniper CBE

  Environmentalist

  INTRODUCTION

  For the earliest humans, a rudimentary knowledge of ecology—how organisms relate to one another—was a matter of life and death. Without having a basic understanding of why animals grazed in a certain place and fruit-bearing plants grew in another, our ancestors would not have survived and evolved.

  How living animals and plants interact with each other, and with the nonliving environment interested the ancient Greeks. In the 4th century BCE, Aristotle and his student Theophrastus developed theories of animal metabolism and heat regulation, dissected birds’ eggs to discover how they grew, and described an 11-level “ladder of life,” the first attempt at classifying organisms. Aristotle also explained how some animals consume others—the first description of a food chain.

  In the Middle Ages (476–1500), the Catholic Church discouraged new scientific thought, and human understanding of ecology advanced very slowly. By the 16th century, however, maritime exploration, coupled with great technological advances, such as the invention of the microscope, led to the discovery of amazing life forms and a thirst for knowledge about them. Swedish botanist Carl Linnaeus developed a classification system, Systema Naturae, the first scientific attempt to name species and group them according to relatedness. Throughout this time, essentialism—the idea that each species had unalterable characteristics—continued to dominate Western thought.

  Great breakthroughs

  Geological discoveries in the late 17th and early 18th centuries began to challenge the idea of essentialism. Geologists noted that some fossil species suddenly disappeared from the geological record and were replaced by others, suggesting that organisms change over time, and even become extinct. The Frenchman Jean-Baptiste Lamarck proposed the first cohesive theory of evolution—the transmutation of species by the inheritance of acquired characteristics—in 1809. However, some 50 years later it was Charles Darwin—influenced by his experiences on the epic expedition of HMS Beagle—and Alfred Russel Wallace, who developed the concept of evolution by means of natural selection, the theory that organisms evolve over the course of generations to adapt better to their environment. Darwin and Wallace did not understand the mechanism by which this happened, but Gregor Mendel’s experiments on peas pointed at the role of hereditary factors later known as genes, representing another giant leap in evolutionary theory.

  Making connections

  The relationships between organisms and their environment, and between species, dominated ecological study in the early 20th century. The concepts of food chains and food webs (who eats what in a particular habitat) and ecological niches (the role an organism has in its environment) developed, and in 1935, Arthur Tansley introduced the concept of the ecosystem—the interactive relationship between living organisms and the environment in which they live. Later ecologists developed mathematical m
odels to forecast population dynamics within ecosystems. Evolutionary theories also advanced with the discovery of the structure of DNA, and the evolutionary “vehicle” provided by mutation as DNA is replicated.

  “There are some 4 million different kinds of animals and plants in the world. Four million different solutions to the problems of staying alive.”

  David Attenborough

  New frontiers

  Improved technology opened up new possibilities for ecology. An electron microscope can now make images to half the width of a hydrogen atom, and computer programs can analyze the sounds made by bats and whales, which are higher or lower than can be heard by the human ear. Camera traps and infrared detectors photograph and film nocturnal creatures, and tiny satellite devices fitted to birds can track their movements.

  In the laboratory, analysis of the DNA of feces, fur, or feathers indicates which species an animal belongs to, and throws light on the relationship between different organisms. It is now easier than ever for ecologists to collect data, helped by a growing army of citizen scientists.

  New concerns

  Early ecology was driven by a desire for knowledge. Later, it was used to find better ways to exploit the natural world for human needs. As time went on, the consequences of this exploitation became increasingly evident. Deforestation was highlighted as a problem as early as the 18th century, and the problems of air and water pollution became obvious in industrialized nations in the 19th century. In 1962, Rachel Carson’s book Silent Spring alerted the world to the dangers of pesticides, and six years later Gene Likens demonstrated the link between power station emissions, acid rain, and fish deaths.

  In 1985, a team of Antarctic scientists discovered the dramatic depletion of atmospheric ozone over Antarctica. The link between greenhouse gases and a warming of Earth’s lower atmosphere had been made as early as 1947 by G. Evelyn Hutchinson, but it was decades before there was a scientific consensus on the man-made causes of climate change.