The phytotronist and the phenotype: plant physiology, Big Science, and a Cold War biology of the whole plant

The organism strikes back: Chlorella algae and their impact on photosynthesis research, 1920s-1960s

Historians and philosophers of twentieth-century life sciences have demonstrated that the choice of experimental organism can profoundly influence research fields, in ways that sometimes undermined the scientists' original intentions. The present paper aims to enrich and broaden the scope of this literature by analysing the career of unicellular green algae of the genus Chlorella. They were introduced for the study of photosynthesis in 1919 by the German cell physiologist Otto H. Warburg, and they became the favourite research objects in this field up to the 1960s. The paper argues that dealing with Chlorella's high metabolic flexibility was crucial for the emergence of a new conception of photosynthesis, as a plastic, integrated system of pathways. At the same time, it led to new collaborations between physiologists and phycologists, both of whom started to re-orient their studies in ecologically informed directions. Following Chlorella's trail, hence, not only elucidates how experimental organisms forced scientists to change their conceptual approaches and techniques, but also provides insight into the interaction of different lines of research of mid-twentieth century plant sciences.

Commentary: tempo of evolutionary change in ecological systems

As ecology and evolutionary biology developed during the 20th century one thing that frustrated an integration of research programs in these areas was the assumption that ecological and evolutionary processes operated on very different time scales. In 1961 the ecologist Lawrence Slobodkin reflected this assumption in his distinction between "evolutionary time" and "ecological time." This commentary reflects on the four papers in this Special Section that advance our understanding of the history of research at the intersection of phenotypes, genotypes, ecology, and evolution using plants as study organisms. Early in the 20th century at least some researchers, especially in agricultural systems, were already using observations and experiments to show how natural selection could operate over relatively short time periods and small spatial scales. These four studies offer a more nuanced view of the history of our understanding of the rate of phenotypic change via natural selection and the use of experiments to study evolutionary change. They illuminate the route that has led to the current presumption that in many cases ecological and evolutionary processes may indeed operate on similar, not dissimilar, time scales.

Introduction: contexts and concepts of adaptability and plasticity in 20th-century plant science

Nowhere is the problem of understanding the complex linkages between organisms and their environments more apparent than in the science of plants. Today, efforts by scientists to predict and manage the biological consequences of shifting global and regional climates depend on understanding how organisms respond morphologically, physiologically, and behaviorally to changes in their environments. Investigating organismal "adaptability" (or "plasticity") is rarely straightforward, prompting controversy and discourse among and between ecologists and agricultural scientists. Concepts like agro-climatic adaptation, phenotypic plasticity, and genotype-environment interaction (GxE) are key to those debates, and their complex histories have imbued them with assumptions and meanings that are consequential but often opaque. This special section explores the diverse ways in which organismal adaptability has been conceptualized and investigated in the second half of the 20th century, and the multifarious political, economic, environmental, and intellectual contexts in which those conceptions have emerged and evolved. The papers in this section bring together perspectives from the histories of agriculture, population ecology, evolutionary theory, and plant physiology, cutting across Asian, North American, and British contexts. As a whole, this section highlights not only the diversity of meanings of "adaptability" and "plasticity," but also the complex linkages between those meanings, the scientific practices and technologies in which they are embedded, and the ends toward which those practices and technologies are employed.