Research Challenges involved in conserving biological diversity include addressing the numerous scientific issues limiting our understanding of the Earth's biota. Speciation and species diversity, the role of genetic variation in population persistence, its rate of generation and loss in different taxonomic groups and under different ecological conditions, as well as the development of tools for addressing these questions are all significant topics in biology pertinent to conservation issues. The genetics group at the CRES (Center for Reproduction of Endangered Species - a division of the Zoological Society of San Diego) undertakes comparative cytogenetic and molecular genetics studies involving a diverse array of species suitable as models for investigating relative rates of evolution among different taxa, population structure and systematics. Additionally, research pertinent to planning and management for selected mammalian, reptilian and avian species of conservation concern is undertaken utilizing appropriate techniques, including the development and application of new methodologies. Current emphases include molecular evolutionary and population studies involving analysis of nuclear microsatellite allelic variation and nucleotide sequence analysis of mitochondrial genomes. Assessment, planning, monitoring, and management of small populations for conservation will benefit from application of more effective methods of collection and analysis of genetic data.