In the Spotlight—Established Researcher

Frederik Nijhout is a recipient of the Founders' Memorial Award by the Entomological Society of America. He was awarded the A. O. Kovalevsky Medal by the St. Petersburg Society of Naturalists for extraordinary achievements in evolutionary developmental biology. Fred Nijhout is a Fellow of the American Association for the Advancement of Science (AAAS). He is also a Member of the American Academy of Arts and Sciences (AAA&S) and of the National Academy of Sciences (NAS). Google Scholar page: https://scholar.google.com/citations?user=q9z6Pt8AAAAJ. I got my PhD at Harvard in 1974, with Carroll Williams, one of the great insect physiologists. I have been interested in animals and nature since childhood. I grew up in the tropics (Guatemala and Curaçao) surrounded by exotic pets and salt-water aquaria: mostly organisms I was able to capture or collect myself. Going to college, I really considered Biology my only option. I′ve been thoroughly happy ever since. I was doing EvoDevo long before the field had a name, when research that is now under its umbrella was called ‘comparative morphology’ and ‘comparative embryology’. For me, it started in the early 1970s, when I was in graduate school learning about developmental biology. I happened to run into an old German paper by Alfred Kühn that showed that during the development of the wings of Ephestia, the determination of the bands of the color pattern appeared to progress in a wavelike front across the developing wing. Looking into the references in that paper, I discovered that the study of the development and evolution of wings and color patterns in moths and butterflies had been a significant area of investigation in early developmental biology, with dozens of papers published in the 1920s and 30s. Interest in this kind of early developmental biology died after WWII, but I was fascinated by it. At the time, new concepts in developmental biology were emerging, and I thought that ideas in positional information and morphogenetic gradients could be the key to understanding the development of wing color patterns. I was particularly interested because wing patterns are essentially two-dimensional forms of development that occur in a cellular monolayer, and where everything is expressed in colors. That seemed handy. It took almost 20 years to get others interested in this problem, but the development, genetics and evolution of color patterns has now become a well-established, healthy and active field in EvoDevo. Another EvoDevo problem I became interested in quite early is the developmental control of polyphenisms. This developed as a young professor during the 1980s, initially on caste determination in ants with Diana Wheeler, followed by seasonal polyphenisms with Berndt Koch (which also gave us the first toehold on EcoEvoDevo). Polyphenisms are quite common in insects, and some of the alternative phenotypes had originally been described as different species, even though there are no genetic differences between them. That seemed to me to be an interesting problem in both development and evolution. What are the developmental mechanisms, and how can such a system possibly evolve, if there are no genetic differences? As it turns out, all polyphenisms appear to be produced by environmentally induced changes in the secretion of developmental neurosecretory hormones. So this work has brought the brain and physiology into the regulation of development and EvoDevo. In EvoDevo, the Evo has from the very beginning been an adjective of Devo, and in practice the core and driving force of the field has likewise been Developmental Biology. Accordingly, progress in EvoDevo has relied more on new techniques and concepts in developmental biology (such as gene expression analysis and manipulation and gene regulatory networks), than on standard techniques and concepts in evolutionary biology (such as phylogenetics, selection, population genetics and quantitative genetics). Studies in EvoDevo have led to the understanding of Hox genes as master regulators of developmental fate, and have revealed an amazing evolutionary conservation of signaling pathways, genes, and gene regulatory networks in the face of extensive evolutionary divergence of phenotypes. At the phenotypic level, studies in EvoDevo have made great contributions to refining morphometric techniques that have been essential for the analysis of phylogenetic divergence of morphological traits, fluctuating asymmetry and phenotypic plasticity. The future of EvoDevo, like that of everything else, is hard to divine. But perhaps I can put it in terms of what I see is missing and deserves more attention. Too little attention has been paid to linking the molecular/genetic and the morphological. Evolution proceeds by natural selection on phenotypes, not genes, but EvoDevo has been curiously light on understanding how phenotypic diversity is generated. Most research has been done on a given phenotype at a specific stage in development (embryo, larva, adult), and comparing those between species or within a phylogenetic framework. The phenotypes in such studies range from molecular to morphological, but there has been little or no research that attempts to connect the mechanism and pathway by which differences in molecular features, such as gene expression patterns or gene regulatory networks, lead to differences in morphological outcomes. This is difficult work, but I think that the greatest progress in EvoDevo in the future will not come from ever more detailed studies of things we already know, but from research that tracks down pathways over time (in both developmental and evolutionary time) and attempts to uncover how a shared underlying regulatory architecture gradually diverges to produce distinctly different, species-specific, phenotypic outcomes.