Gunnar Svärdson, Professor Emeritus at the Freshwater Laboratory, Drottningholm, Sweden, and Corresponding Fellow of the AOU, was born on 19 September 1914 in Stockholm. He celebrated his 90th birthday shortly before his unexpected death in Stockholm on 6 November 2004. He was one of Sweden’s best known and most highly respected evolutionary biologists and ornithologists.

His strong interest in natural history emerged early. After finishing school, he studied zoology, botany, and geography at the University of Stockholm. Like many biologists, he started out primarily as a bird watcher and had a lifelong passion for ornithology. Yet his best-known scientific contributions were based on studies of freshwater fish. In 1945 he presented his doctoral thesis, titled simply Chromosome Studies on Salmonidae. In his thesis, which is still cited, Svärdson focused on “a species“ of whitefish (Coregonus) in Scandinavian freshwaters and demonstrated that it actually consisted of up to half a dozen genetically incompletely isolated populations, each adapted to a certain set of environmental circumstances. The “introgression“ of genes into each of them from one or more of the others prevented their definite fission and kept them in a state of lasting incipiency. Svärdson’s work led to an entirely novel appreciation of the evolutionary history, genetics, and systematics of the genus Coregonus, and to this day it provides one of the most fascinating and intriguing examples of the dynamics of speciation in population groups. Svärdson applied an impressive array of methods and concepts, including cytology, biogeography, and behavior. A similar approach was later used by him to study other groups of salmonids and by other researchers for a great variety of other animal taxa. Moreover, in today’s world of biotic globalization and violent anthropogenic perturbations of animal and plant communities, Svärdson’s insights into the processes of species formation and splitting have received increased attention. Hybridization is widely regarded as one of the theoretically and practically most important phenomena in population genetics, as well as in the struggle to preserve the world’s biodiversity.

As the ideas of the “Modern Synthesis“ reached Scandinavia during and after the war, Svärdson was one of the few who quickly realized the fundamental significance of this new way of thinking and became its leading proponent and defender in Sweden. Breaking as they did with the Linnaean tradition of systematics in Sweden, the new ideas aroused acrimonious feelings in wide and influential circles, and Svärdson was involved in many heated arguments. It is truly refreshing to read his crystal-clear contributions to this debate, and more than almost anything he published, those texts show him decades ahead of his time. Very little would have to be changed to make these publications reflect today’s state of the art in evolutionary biology.

Another major contribution flowed from Svärdson’s detailed familiarity with birds and bird communities in Scandinavian forests. In a comparatively brief paper in Oikos (1949), he presented an innovative model of the different evolutionary and ecological consequences of intraspecific and interspecific competition. Although based on bird work, the general applicability of the model was quickly realized in many quarters, and more than one of the most prominent (if aging) ecologists of the late 20th century have in conversations mentioned to me that “Svärdson 1949“ was a major eye-opener for them and greatly influenced their own research in community ecology. Svärdson once related to me that this particular paper had been summarily rejected by the editor-in-chief of the new journal, with the argument that “this is not ecology.“ In those days, long before MacArthur, the attitude in Scandinavia was that ecology consists solely of measuring “abiotic“ factors and correlating them with the more-or-less poorly known local distributions of various animals. It was simply inconceivable to most ecologists in those days that competition could have an effect on patterns of distribution and composition of communities. Svärdson told me that the paper was grudgingly accepted only after he pointed out that he was, after all, one of the founding fathers of Oikos and therefore should be allowed to influence the scope of the new journal and, hence, what is inside and outside the field of ecology.

Gunnar Svärdson’s willingness to invest both time and energy in the service of ornithology is amply documented by the fact that he was one of the founders of the Swedish Ornithological Society in 1945 and of the Society’s bird station at Ottenby on the island of Oland, in the Baltic Sea off the southeastern Swedish coast. Immediately after World War II, Svärdson and some of his friends raised money for a bird station at Ottenby, and 1946 was its first year of operation. Today, after almost 60 years, it is as active as ever and plays a significant role both in ornithological research and in the Swedish program for environmental monitoring.

Svärdson and his family spent each summer in the late 1940s and early 1950s at Ottenby, and many of us young bird enthusiasts employed at the bird station to count the migrating birds or to ring them greatly enjoyed their company. Svärdson himself was a master of “enlightening conversation,“ and we students used to look forward to the occasional day of foul weather that gave us some respite from the round-the-clock field work and a little time for conversations with Gunnar about all matters evolutionary. I was certainly not the only one among those young bird enthusiasts to have had my professional life greatly influenced by what I learned during those discussions at Ottenby.

For most of his life, Svärdson was employed at the Freshwater Laboratory at Drottningholm and served as its director from 1963 to his retirement in 1980. According to his friends at the laboratory, there was no significant decline in the intensity of his research after 1980, and even in his last weeks he was busy preparing a major article in which he was to present a new view on certain puzzles he had discovered in the biogeography of Scandinavian salmonids. His scientific achievements were recognized in many ways. In 1966, the Swedish government conferred on him the rare honor of a Personal Professorship. He was elected Corresponding Fellow of the AOU in 1958, and a member of the Royal Swedish Academy of Sciences in 1975. He was given the Award of Excellence by the American Society of Fisheries in 1981.

Svärdson’s life was long and productive. His passion for science, the breadth and depth of his knowledge and experience, his openness to new ideas, and his willingness to share his insights with students and colleagues made him a model to many. His skill and ardor in defending curiosity-based research against its many enemies was renowned. Many of his ideas still stimulate research in different parts of the world and will no doubt continue to do so for a long time. He will be sorely missed as a respected colleague, teacher, and good friend.