History of Ecological Ideas
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Introduction

  • Although the real explosion in ecological studies did not take place until the 1960's, ecological thought goes back to the ancients

  • Buffon and Linnaeus also played a role influencing the great explorers of the eighteenth and nineteenth centuries. For these explorers the ultimate goal was no longer just to collect and describe species, but to understand the interaction of organisms with their environment


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Alexander von Humboldt(German, 1769-1859)

  • From a well-to-do family

  • Traveled extensively throughout Europe, America, and Russia

  • Had a holistic view of nature


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Ernst Haeckel (German, 1834-1919)

  • He was the leading German disciple of Charles Darwin

  • He coined the term “Ecology”

  • He originally used the Greek spelling Oecologie, and defined it as “the science of the relations of living organisms to the external world, their habitat, customs, energies, parasites, etc.”


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  • Haeckel derived the new label from the same root found in the older word “economy” (“Oekonomie”): the Greek oikos, referring originally to the family household and its daily operations and maintenance

  • The reason was that at that time, people thought that national economic affairs could be understood as an extension of the housekeeper’s budget. Haeckel thought that the Earth constituted a single economic unit


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  • From the beginning there was a strong Darwinian sense in ecology. Haeckel said in 1869 that ecology was “the body of knowledge concerning the economy of nature (...) the study of all those complex interrelations referred to by Darwin as the condition of the struggle for the existence”

  • For many years the term was ignored. The use “the economy of nature” instead as in previous centuries “natural economy,” was used to refer to physiology


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  • The people working on the subject had little contact with each other. Although literally thousands of papers were published in those decades dealing with the number of species and individuals within a certain measured area and hundreds of new terms were proposed, ecology remained a rather static and descriptive science

  • The term was retaken initially as “oecology” and then with its modern spelling “ecology” after the International Botanical Congress of 1893


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Major Revolutions in the Ecological Thought each other. Although literally thousands of papers were published in those decades dealing with the number of species and individuals within a certain measured area and hundreds of new terms were proposed, ecology remained a rather static and descriptive science

  • Three major events revitalized the field:

    a) The calculations of Lotka-Volterra: cycle of population changes due to the predator-prey relations, as well as growth, decline, and cycle of populations

    b) Emphasis on competition: the principle of competitive exclusion and its experimental testing by Gause

    c) Attention to energy turnover problems, particularly in freshwater and in the ocean


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Biogeography each other. Although literally thousands of papers were published in those decades dealing with the number of species and individuals within a certain measured area and hundreds of new terms were proposed, ecology remained a rather static and descriptive science

  • The ancients (Hippocrates, Aristotle, Theophrastus, and others) had written about regional differences in the distribution of animals and plants and ascribed the differences to climatic factors

  • They tried to explain the facts that there were elephants in Africa and Asia but not in between to the facts of former connections


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  • The imposition of the literal interpretation of the Bible in western thought created major problems

  • The idea was that all plants and animals originated in the Garden of Eden, after the Flood they had been “rescued” in Noah’s Ark from which they had dispersed again supposedly from Mount Ararat

  • This interpretation, however, accepted the fact that species were not fixed in space but that they had to disperse and migrate


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  • Buffon postulated that when the Earth cooled off, life was created in the far north because the tropical regions were still too hot for sustaining life. “The earth makes the plants; the earth and the plants make the animals”

  • Still, he could not explain why the tropical faunas of Africa and America, for example, were so different


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  • The first researchers interested in ecology were geographers. This was a very prominent discipline in the 19th. century. The world was still being mapped

  • Two schools appeared:

    a) biogeographers: distribution of species around the world (the controlling interest was taxonomic rather than ecological)

    b) physiognomists (“ecological geographers”): they talked about vegetation rather than flora, for example


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  • For the latter, three principles dominated the new science: geographers. This was a very prominent discipline in the 19

    a) classification of plants by their adaptive forms or structure rather than by their taxonomy

    b) emphasis on plants as social beings forming integrated societies

    c) identification of climate as the crucial determinant of both individual life forms and the communal pattern


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  • The latter part of the 19 Warmingth. century produces terms such as “mutualism”, “comensalism”, “symbiosis”, “succession”, “climax” as well as a system of classification for plants communities such as “hydrophytes”, “xerophytes”, “mesophytes”, etc.

  • The beginning of the 20th. century begins with the development of “autoecology”: the environmental physiology of an individual organism and also the first look by zoologists to this new science

  • For many years, until the 60's there was still talk of “plant ecology” and “animal ecology” as separate entities


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The Darwinian Revolution Warming

  • On Darwin’s diary of the voyage of the Beagle, as well as in his Origin and autobiography, he mentioned again and again the importance of the knowledge of the distribution of species to understand their origin

  • He was particularly struck by two facts:

    a) The species of the temperate zones of South America were closely related to the ones in the tropical areas of that continent rather to the ones of the temperate zones of North America

    b) That fauna of islands were closely related to those of their closest continent


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  • For him, thus, distribution was not random. The question was what factors influence the introduction of species in a particular area?

  • He is considered to be the father of zoogeography although Wallace also made important contributions

  • A radical departure from Linnaeus who believed that all plants derived from a mountainous tropical island (Eden?) from which all spread all over the world


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  • Alphonse de Candolle proposed (1855) 20 botanical regions (“centers of creations”)

  • Louis Agassiz (1857) was a creationist for whom “every unsolved biological mystery was the product of the hand of God.” However, his “Ice Age Theory” laid the bases for explanations related to the changing earth

  • Darwin’s writings would break the non natural explanations for the origin and distribution of animals and plants. For him dispersal was due to two factors: the ability to get to a new locations and the ability to colonize it


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The Land Bridge Idea (“centers of creations”)

  • Darwin’s ideas, however, did not seem able to explain the discontinuities in distribution patterns in particular. To solve this problem numerous scientists proposed the idea of connections by “land bridges.” These researchers had two things in common: low opinion of the dispersal abilities of animals (particularly mammals) and total disregard of the geological evidence


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  • The real questions came from astonishing facts: beavers in Eurasia and America, same plants in the Pyrenees and in the Alps, mountains of Scandinavia and islands of the Arctic lowlands without anything in between and European plants in Tierra de Fuego, the strangeness of Australian biota (“disjunct distributions”)

  • This became one of the major issues of biogeography during the first half of the 19th. century


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  • E. A. W. Zimmermann (1778-1783) proposed that the distribution of mammals can not be sufficiently explained by climate and rather it had to be explained by the history of earth. He proposed the land bridges theory to explain why continents and islands share the same fauna is because of former connections between then (“land bridges”). He is considered the father of historical biogeography.


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