Experimental taxonomy was a diverse area of research, and botanists who helped develop it were motivated by a variety of concerns. While experimental taxonomy was never totally a taxonomic enterprise, improvement in classification was certainly one major motivation behind the research. Hall's and Clements' belief that experimental methods added more objectivity to classification was almost universally accepted by experimental taxonomists. Such methods did add a new dimension to taxonomy — a dimension that field and herbarium studies, however rigorous, could not (...) duplicate. Nonetheless, experimental techniques were never completely divorced from traditional taxonomic methods. In practice, all experimental taxonomists employed a combination of descriptive and experimental methods. Most researchers freely acknowledged a debt to traditional taxonomy. Furthermore, the greater rigor of twentieth-century taxonomy was not due entirely to experimentalism. Both the experimental and descriptive aspects of taxonomy were improved by the increased use of quantitative methods, particularly statistics.52From the beginning, a number of experimental taxonomists were interested primarily in classification. But many approached their research from fields other than taxonomy. These botanists were concerned primarily with ecological and genetic problems rather than with classification. There is little indication that they drew a sharp distinction: for example, taxonomic and cytogenetic conclusions were interwoven in Babcock and Stebbins' 1938 study of Crepis 53 (this was even more true of Babcock's final mongraph on the genus, published in 1947). Similarly, the extensive series of monographs, “Experimental Studies on the Nature of Species,” initiated by the Carnegie Institution group in 1940 combined ecological, cytogenetic, and taxonomic conclusions. Indeed, the significance of the major projects completed by experimental taxonomists was largely due to the fact that they were comprehensive studies rather than strictly taxonomic or cytogenetic.In a general sense, the primary motivation behind much of experimental taxonomy was evolutionary. Beginning in the second decade of the century Hall and Clements exhorted taxonomists to take an explicitly evolutionary perspective on research. Hall undoubtedly spoke for the majority of experimental taxonomists when he stated, “If there be anything at all to organic evolution, then taxonomy is dealing with the products of evolution and it is this that gives to taxonomy both its highest mission and its greatest responsibility.”54Aside from a common interest in evolution, however, the theoretical orientations of experimental taxonomists were varied. This diversity is strikingly illustrated by the evolutionary views of members of the Carnegie Institution research group. Experimental taxonomy was initiated by Clements as one aspect of his Lamarckian study of adaptation and speciation. In contrast, Hall's research was inspired by a broad concern for evolutionary problems. Hall rarely referred to specific evolutionary mechanisms; rather, he applied a general conception of evolutionary processes to deduce phylogenetic relationships. His later associates at the Carnegie Institution explicitly dissociated themselves from Clements' theoretical framework. The neo-Darwinian interpretations of adaptation and speciation presented by Clausen, Keck, and Hiesey could hardly have been more different than those of Clements. However, this major shift in theoretical orientation should not obscure significant similarities between the research of Clements and later Carnegie workers. In terms of research problems and methodology, the first volume of “Experimental Studies on the Nature of Species” was an extension of the Clementsian research program. Clausen, Keck, and Hiesey's monograph was the mature discussion of transplant experimentation that Clements had very tentatively initiated during the first decades of the twentieth century. The bond that linked the members of the Carnegie Institution research group to experimental taxonomists in general was one of shared methodology rather than common theoretical orientation. While Clements' evolutionary views were eventually repudiated, his enthusiasm for innovative experimental methods was shared by later workers.The development of experimental taxonomy faced significant problems. During the period 1920–1950 this area of botanical research remained a hybrid discipline. The aims and scope of experimental taxonomy were never articulated in a completely unified manner. Consequently, even among experimental taxonomists, there were disagreements over the relation of their research to other botanical endeavors. Even though experimental taxonomy had close ties with general taxonomy, a number of experimental taxonomists questioned the “taxonomic” nature of their research55. Even to the extent that this hybrid discipline could be identified as a branch of taxonomy, problems arose. Taxonomists, as we have seen, were justifiably skeptical of what appeared to be a rapid influx of untested methods and ideas. Experimental taxonomists were not merely incorporating well-accepted methods from ecology and cytogenetics; during the period 1920–1950 the fields from which experimental taxonomists borrowed were themselves undergoing major theoretical and methodological changes. Despite problems and conflicts, experimental taxonomists did contribute improvements to classification. Furthermore, they made significant contributions to plant ecology and evolutionary genetics.The development of experimental taxonomy indicates that twentieth-century botanists were not necessarily isolated in naturalist and experimentalist camps. The joint session of taxonomists, cytologists, and geneticists at the 1926 International Congress of Plant Sciences indicates communication among specialists fairly early in the century. The papers and commentaries presented during this session do not reveal the hostility and intolerance that supposedly characterized encounters between experimentalists and naturalists. Nor do they suggest incompatible conceptual worlds separating geneticists and taxonomists.Discussions between taxonomists and other specialists were not limited to a single international congress. Particularly during the 1930s discussions among specialists appear to have been fairly widespread. Groups such as the Biosystematists and the Society for the Study of Systematics in Relation to General Biology served as forums for discussion among biologists from a variety of disciplines. The naturalist-experimentalist dichotomy tends to obscure the broad research interests of a number of prominent twentieth-century botanists. Most of the experimental taxonomists cannot be characterized adequately as either naturalists or experimentalists. Traditionally trained taxonomists such as Hall, Keck, and Turrill throughout their careers participated in both experimental and herbarium research. And a number of specialists in fields other than taxonomy took an active interest in taxonomic problems, not necessarily limited to experimental aspects. For example, Anderson suggested a number of innovations to make herbarium collections more amenable to statistical analysis.This historical study of experimental taxonomy indicates a different relationship between experimentalism and taxonomy than that portrayed by the naturalist-versus-experimentalist dichotomy. F. E. Clements originated experimental taxonomy as a revolt against descriptive botany. In retrospect, this revolution was not vigorously waged and was not successfully completed. Experimental taxonomy was never an entirely experimental approach to botanical research. Even the most ardent advocates of experimentalism relied heavily on methods inherited from traditional taxonomy. Moderate exponents of experimental taxonomy stressed the compatibility of experimental methods, field observation, and herbarium techniques. Attempts to fuse cytogenetics, ecology, and taxonomy during the period 1920–1950 resulted in an impressive body of research. However, this fusion constituted neither a repudiation of descriptive botany nor a complete revision of taxonomic theory of practice. (shrink)

Darwin's theory of evolution brought to an end the static view of nature. It was no longer possible to think of species as immortal, with secure places in nature. Fluctuation of population could no longer be thought of as occurring within definite limits which had been set at the time of creation. Nor was it any longer possible to generalize from the differential reproductive potentials, or from a few cases of mutualism between species, that everything in nature was “fitted to (...) produce general ends, and reciprocal uses.” 134 The appeal to “design” could no longer be substituted for answers to questions concerning animal demography. Instead, the dynamics of a population had to be viewed as the outcome of species' struggle against animate and inanimate factors in the environment. Both the members of a species and the environmental factors tend to vary randomly, and therefore neither evolution nor population dynamics could be fully understood alone. For this reason Darwin's linking of the two subjects was inevitable and not merely an historical accident. Since Darwin had shown that no automatic equilibrium existed, he demonstrated the importance of closer study of the causes of population dynamics and extinction. He also indicated that an understanding of population depends upon the development of a broad knowledge in ecology.Viewed from another direction, Darwin's work ended the early modern era of population studies by clarifying three interrelated problems which were important for understanding population: extinction, distribution, and the nature of species. The components of his answer had been discussed in the eighteenth century, but there had not existed enough evidence for the completion of the revolution in thought which had then begun. At the beginning of the nineteenth century, Playfair found the evidence for extinction conclusive, and, in spite of Lamarck, Curvier convinced the scientific world that there could no longer be any doubt about it. This was a step the importance of which, with his limited knowledge of biogeography and population, Cuvier could not have fully realized. Lamarck attempted, with his evolutionary theory, to circumvent the necessity for admitting extinction, but he overestimated the adaptability of organisms and in doing so he underestimated the importance of competition and the whole field of ecology. On the other hand, he was not willing to let questions such as the origin of species remain taboo to science. The origin of species was a biogeographical as well as a paleontological question. Humboldt correlated environment with the distribution of species and conveyed the impression that plant communities are subject to change. De Candolle, following the lead of Linnaeus and Humboldt, emphasized the ecological aspects of biogeography, not only the importance of habitat and range, clearly showing the ecological effects of competition. The entomologists Kirby and Spence took a faltering step toward understanding the relationship between population and ecological role, but they fell short of any significant new conclusions. Neither they nor Swainson could fully comprehend the new perspective of De Candolle.Lyell was able to bring together the evidence from these three lines of investigation and weave them into an important synthesis that almost accomplished that Darwin later did. Although opposing Lamarck's theory of evolution, Lyell had a dynamic view of ecology. He realized that population dynamics offered an important key to the understanding of biogeography. Since he knew that species become extinct, he investigated closely the factors which could either preserve or extinguish species. While explaining these factors, he described the interrelationships of species in greater detail than had ever been done before. Forbes continued to develop Lyell's ecological concepts, and his first-hand field experience enabled him to describe biotic communities more concretely than Lyell had.Having the advantages of Lyell's understanding and his own experience from a global voyage, Darwin could take the final step from the static to the dynamic concept of life. He had seen populations fluctuating and also fossil species in South America, and on the Galapagos Islands he had encountered a biogeographical problem that could not be credibly solved without the idea of evolution. However, the bare idea of evolution did not fully answer his questions. He sought physiological causes of extinction before he read Malthus and realized that De Candolle and Lyell had correctly emphasized the importance of competition. Darwin found that, in order to understand evolution, he needed to improve his understanding of ecology. He wanted to know when populations were most easily decimated, how extensive were competition and cooperation, what effects parasites have upon populations, and what changes occur in biotic communities when a species is either added or subtracted. He contributed to some extent to answering these questions. Though there remained much for others to do, there was now a new and more secure theoretical framework within which later studies could be interpreted. As Ernst Mayr has observed, Darwin's “consistent thinking in terms of population has had an impact on biological theory and practice which is second only to his sponsorship of natural selection as the mechanism of evolution.” 135. (shrink)

Drawing on his investigation of over one hundred mid-Victorian British newspapers and periodicals, Alvar Ellegård describes and analyzes the impact of Darwin's theory of evolution during the first dozen years after the publication of the Origin of Species . Although Darwin's book caused an immediate stir in literary and scientific periodicals, the popular press largely ignored it. Only after the work's implications for theology and the nature of man became evident did general publications feel compelled to react; each social group (...) responded according to his own political and religious prejudices. Ellegård charts the impact of this revolution in science, maintaining that although the idea of evolution was generally accepted, Darwin's primary contribution, the theory of natural selection, was either ignored or rejected among the public. (shrink)

Ernst Mayr''s contributions to 20th century biology extend far beyond his defense of certain elements in evolutionary theory. At the center of mid-century efforts in American evolutionary studies to build large research communities, Mayr spearheaded campaigns to create a Society for the Study of Evolution and a dedicated journal,Evolution, in 1946. Begun to offset the prominence ofDrosophila biology and evolutionary genetics, these campaigns changed course repeatedly, as impediments appeared, tactics shifted, and compromises built a growing coalition of support. Preserved, however, (...) were designs to balance the community and journal with careful equation of status and explicit partitioning of responsibilities within the working coalition. Choice terms such as cooperation and unity carried a strong political message. Mayr''s editorship ofEvolution provides a superb example of these balancing efforts. The mid-century infrastructural activities described herein also represented aggressive attempts to leverage control across several layers of community. Leaders of these campaigns sought: (1) to promote evolutionary studies as a modernized research discipline and place it at the center of American biology, (2) to promote evolutionary studies within existing disciplines — e.g. systematics, genetics, and paleontology, (3) to foster certain research styles within evolutionary studies, and (4) to emphasize certain solutions to prominent research questions. Throughout, Mayr interjected his priorities, tactics and energy. (shrink)