Introduction of Steven A. Nadler, recipient of the Henry Baldwin Ward medal for 2013.

Members of the American Society of Parasitologists (ASP) and guests, it is a great pleasure and honor to introduce Steven A. Nadler as the 2013 Henry Baldwin Ward medalist. The Henry Baldwin Ward medal is awarded in recognition of outstanding contributions to the field of parasitology. In this respect, Steve has had an exemplary career as an internationally renowned parasitologist who has made important contributions involving most traditional parasite groups including the Apicomplexa, Acanthocephala, chewing lice, cestodes, trypanosomes, and, most significantly, the nematodes. His outstanding contributions to research are matched with an incredible dedication to the promotion of parasitology and the ASP, including service as an associate editor for the Journal of Parasitology and other journals in our field, committee work, and, most important, a recent term as president of our society in 2008. Steve has also recently joined Larry Roberts and John Janovy Jr. in coauthoring the latest edition of ‘‘Foundations of Parasitology.’’ I have known Steve for many years now, having worked in his laboratory as a postdoctoral researcher from 2000 to 2002. He is an important collaborator and also a close friend, and so it’s a special honor to be able to introduce him and for him to receive this distinguished award and to join other outstanding parasitologists who have previously been recognized as Ward medalists. I first met Steve in 1992 when I was a graduate student attending my first ASP meeting in Philadelphia. Fellow students had talked him up to be a superstar, one of the best in molecular systematics. I was hesitant to approach him with my questions on systematics at the time, but when I did, I was relieved to find an extremely kind, helpful, down-to-earth person who was also quite knowledgeable in molecular systematics and nematodes. He was, indeed, a parasitology superstar. At that point in his career, he had already accomplished a lot in molecular systematics but was just getting started with what has since been an incredible number of contributions to our knowledge of nematode phylogenetics, molecular methods in systematics, and an understanding of relationships within other groups based on molecular approaches. Steve will not remember that 5-min conversation from 20 yr ago, but for me it was one of those special highlights for a student attending one of his first big meetings. Steve was born in St. Louis, Missouri, and his academic career began at Missouri State University, in Springfield, where he graduated in 1980. As a junior, he left Missouri and spent a year at the University of Hawaii. Here he had one of his first introductions to the field of parasitology, and he decided to pursue graduate studies in the field, ultimately choosing the Louisiana State University (LSU) Medical Center in New Orleans, where he completed his Masters thesis and, in 1985, his Ph.D. At LSU, Steve met and was eventually advised, together with Joe Miller, by Herb Dessauer, who was a pioneer of molecular systematics. His Ph.D. work on the systematics of ascaridoid nematodes set the groundwork for many later contributions that he has made on this group. These contributions, in addition to clarifying relationships in the ascaridoid nematodes, have provided a methodology that has been used by many other researchers, including myself, for working on the systematics of other nematode groups as well as other parasites. As a postdoc, Steve worked with Dr. Mark Hafner at the Museum of Natural Science, LSU, Baton Rouge. Here they worked on the cophylogeny of pocket gophers and their lice. It was this collaboration with Hafner that resulted in pioneering and substantial contributions to the field of comparative evolutionary biology. This postdoctoral research yielded papers in the journals Nature, Science, Systematic Zoology (now Systematic Biology), and Evolution, which collectively have been cited more than 600 times. The papers in Science and Nature alone have each been cited more than 200 times as seen in current databases. Both the empirical and theoretical results of these publications had a considerable impact on the field of comparative evolutionary biology—and in particular, substantially advanced the field of host–parasite coevolution by being the first to demonstrate how genetic data can be used to test hypotheses of cospeciation. In this research molecular data (from the host–parasite system of pocket gophers and their lice) were obtained and approaches developed for investigating cospeciation, timing of speciation events, and rates of molecular evolution in groups of ecologically associated organisms (such as hosts and their parasites). This research has proven to be influential in areas of biology extending beyond host–parasite cospeciation, including molecular evolution and biogeography. Both the empirical data and the ideas developed in these publications have served as a catalyst for many subsequent developments and publications in the field of host–parasite cophylogeny. Today, this work appears regularly in our textbooks in parasitology, evolution, biogeography, and related fields. Soon after carrying out the pocket gopher/louse research, Steve got a faculty position in the Biological Sciences Department at Northern Illinois University, followed a few years later by a move to the University of California (UC) in Davis, where he is currently professor in the Department of Entomology and Nematology. During this time, especially at UC Davis, Steve built on his earlier doctoral work to make important contributions to our understanding of ascaridoid relationships, publishing over a dozen papers on this group. His studies of ascaridoids (including, among others, Parascaris, Toxocara, and Ascaris) provided the first well-supported phylogenetic hypotheses for this group. They were also among the first to explore population genetic diversity and variation in nematodes. These studies highlighted the importance and implications of microevolutionary processes associated with complex host–parasite assemblages. Several publications, in collaboration with his Italian and Scandinavian colleagues, have addressed the systematics of DOI: 10.1645/13-373.1