Scientists in Europe and the United States Lay the Foundation for the Modern Science of Ecology

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Scientists in Europe and the United States Lay the Foundation for the Modern Science of Ecology

Overview

Ecology is the branch of science that deals with the interrelationships of plants, animals, and the environment. The world has a great variety of living things ranging from simple one-celled organisms, such as bacteria and fungi, to man. No organism lives by itself. In some way, each depends on the living and non-living things in the environment. This perception of interdependence did not evolve until late in the twentieth century. Nineteenth-century researchers on expeditions, plant and animal scientists in Europe, and American naturalists all contributed bits and pieces. Their efforts would continue into the early part of the twentieth century. Work on various elements of ecology was fragmented and not connected, and because of communication problems, research efforts were not well known or publicized. Several scientists studied different populations, communities, and parts of an ecosystem. Both plant and animal ecology developed separately until American biologists and environmentalists in the twentieth century began to emphasize the biotic whole.

Background

No one can point to the exact place where ecology began. There is no founder or father. The Greek Theophrastus (c. 370-285 b.c.), one of Aristotle's students, described the morphology or make up, natural history, and therapeutic use of plants. He even made the effort to develop a scientific naming system or nomenclature. More than 500 plants were divided into what is known as genera. He also described seed germination and sexual reproduction of flowering plants. The first use of the term "ecology" was by a German zoologist and evolutionist, Ernst Haeckel (1834-1919). He declared that all nature is explained in a unified theory of evolution and used the term "oekologie" in his book Generalle Morphologie der Organismen ("General Structure of Organisms") in 1866. He coined the term ecology for interrelatedness relating to evolution. Scientists today have specific meanings for the term ecology. Major precepts of ecology at the end of the twentieth century follow: 1) All living and non-living things are interconnected. 2) The world is divided into separate units known as ecosystems, for example a forest; populations are factors in an ecosystem. 3) An area where all organisms live together is called a community. 4) Organisms have energy roles as producers, consumers, and decomposers. These links are represented by food chains or food webs. To arrive at these precepts, animal and plant physiologists of the nineteenth century laid the foundations through many separate contributions. However, it was not until late in the twentieth century that the strong conceptual bases for ecology were focused.

Impact

A force that began in the eighteenth century and continued in the nineteenth was the biological expedition sponsored by the government of Great Britain. Such endeavors had interesting names and went to exotic places to study plants and animals. Early travelers were no more than curious adventurers, but as the expeditions continued, they became more scientific. The biologists became trained observers. From an expedition called the "Investigator" in 1801, botanist Robert Brown (1773-1858) wrote a classic work on the plants of Australia and New Zealand, describing how certain plants adapt to differing environmental conditions. In 1831 the H.M.S. Beagle landed on the Galapagos Islands off the coast of Ecuador. On board was geologist Charles Darwin (1809-1882), who began to ponder the significance of the strange animals that had developed on the isolated islands. He also collected specimens and took many notes on the living things in South America and Australia. He noted the variations of animals that had adapted to different environments and presented his ideas of how organisms evolved at a scientific meeting in 1858. His theory of evolution became an exploding bomb throughout the world. These expeditions piqued the development of zoogeography, or the study of animals, and phytogeography, the study of plant distribution.

In 1858 English ornithologist (one who studies birds) Philip L. Sclater based Earth divisions on the kinds of bird inhabitants. Not long after, biologist Adolf Engler (1844-1930) did the same type of world classification for plants. Many individual adventurers made a contribution. From 1854 to 1862 English naturalist Alfred Russel Wallace (1823-1913), along with British naturalist Henry Walter Bates (1825-1892), traveled to the Amazon and later to the Malay Archipelago to collect specimens. Here, he grouped the animals according to an imaginary line that became known as Wallace's line. The animals west of the line were like those in Asia; those east of the line were like the Australian animals. After reading Thomas R. Malthus's (1766-1834) "Essay on Population," he reported that he was struck with the idea that natural selection is a process by which historical changes occur in a plant or animal species. The story is told how he arrived at his ideas, independent of Charles Darwin. Wallace was in the Molluccas or Spice Islands and became ill with malaria. While he was struggling with the terrible fevers and chills of the infection, he perfected his ideas of the survival of the fittest and evolution.

Both the work of Wallace in zoogeography and Sir Joseph Dalton Hooker (1817-1911), a plant collector and systematist, laid the foundation for the emerging biogeography of the nineteenth century. They had an influence on the work of Charles Darwin, who mentioned their works in his seminal book, The Origin of Species.

In the early and mid-1900s biologists in Europe and America approached the study of living things from two different points of view. Europeans botanists concentrated on structure, composition, and distribution of plant communities. America botanists were fascinated with the development or changes in plant communities, called succession. Study of zoology likewise developed as comparative zoology, and it was completely dominated as the century progressed by evolution and population dynamics.

The early botanists of Europe began with studies of the geography and structure of plants. However, transition from phytogeography to plant ecology progressed throughout the century.

Austrian botanist Gottlieb Haberlandt (1854-1945) was the first person to study plant tissue culture. At the University of Tübingen Haberlandt studied under Simon Schwendener, who emphasized that structure and function must be studied together. Haberlandt later succeeded Schwendener as chair of plant physiology at the University of Berlin. Haberlandt wrote a book in 1884 in which he classified plants based on the function of twelve tissue systems, such as mechanical, absorptive, or photosynthetic. His system was not accepted by other botanists, but his studies of the relationships of structure and environment led to later developments in ecology.

Andrea Franz Wilhelm Schimper (1856-1901) was one of the first to divide the continents into floral regions. He traveled extensively in Brazil, Java, and Africa and wrote about the climatology and physiology of the world's vegetation. He described how plants spread to new areas and how they adapt to these new territories. Another European, Danish botanist Johannes Eugenius Warming (1841-1924), related living plants to their surroundings. Beginning his studies in Greenland, he described how the structures of plants adapted to their surroundings. In his 1895 study called Oecology of Plants, he grouped and characterized plant communities as a group of species growing in the same locality and subject to the same external conditions.

U.S. botanists took a more pragmatic approach. Charles Edwin Bessey (1845-1915) introduced the systematic study of plant morphology and experimental laboratory at the college levels at the Iowa State University Agricultural College and the University of Nebraska. George Perkins Marsh (1801-1882) was a U.S. diplomat and congressman who had the foresight of government's role in natural resource management. His book Man and Nature (1864) was one of the most significant of the nineteenth century in ecology and resource management.

The science of oceanography also developed in the last half of the nineteenth century. However, several scientists laid the foundation. From 1872 to 1876 under the leadership of Charles Wyville Thomson, scientists aboard the British ship HMS Challenger studied oceanography, meteorology, and natural history. The teams made vast collections of sea life and were the first to determine the importance of plankton, the free-floating plants and animals that are the beginning of the food chain for other animals. The science of marine biology was born with this trip. Karl August Möbius (1825-1908) was a German zoologist who greatly contributed to marine biology. He conducted research on corals and foraminifera, (tiny one-celled animals with calcium shells), leading to the discovery of symbiotic relationships in marine invertebrates. He was also interested in fishery biology, mussels, oyster breeding, and possibly pearl cultivation.

Louis Agassiz (1807-1873) was a Swissborn U.S. naturalist who developed an interest in ichthyology when he inherited a collection of Brazilian fishes from the Amazon. He traveled throughout Europe, studying both live species and fossils of extinct species of fish and the animals that were found with them, such as echinoderms and mollusks. In 1836 he began a study of the glaciers in Switzerland and concluded these were great sheets of ice that covered large areas. In 1846 he moved to the U.S., settling as a professor of zoology at Harvard. He published many papers and worked to assist a complete revolution of the study of natural history in the U.S. Almost every notable U.S. naturalist in the nineteenth century was a pupil of Agassiz.

American naturalists began the rudiments of the environmental movement by popularizing nature. John James Audubon (1785-1851) became known for his drawings of North American birds. In the summer of 1869 John Muir (1838-1914) made his first long trip to Yosemite and became known as the most romantic and sublime of the naturalists. Taking the American experience an additional step was Clinton Hart Merriam (1855-1942), a biologist and ethnologist who helped found the National Geographic Society (1888) and the U.S. Biological Survey (1896), which is now the Fish and Wildlife Service.

Scientists of the nineteenth century made unique contributions to the science of ecology. From the adventurous expeditions to the pure botanists and zoologists of Europe to the American practical and romantic naturalists, who encouraged government resources management, the whole science emerged. Today's ecological studies and the environmental movement are powerful forces that will continue to be refined in the twenty-first century.

EVELYN B. KELLY