Evsey Kosman is a mathematician. He develops general and logically consistent approaches and metrics for measuring and decomposing genetic, functional, and phylogenetic variability to address a wide range of topics in Population Genetics, Ecology, and Conservation. His research interests also include analyzing structural relationships of operational units at different hierarchical levels of biological organization and at various spatiotemporal scales. In particular, Evsey does research in Plant Protection and Population Genetics of Plant Pathogens encompassing elaboration of new approaches to study of plant pathogen populations and a comprehensive analysis of specific plant-pathogen systems.