Ted J. Case
Professor of Biology, UCSD

e-mail: case@biomail.ucsd.edu

         We study how interactions between species, such as competition, predation, and parasitism, affect the spatial distribution of individuals and their ecologies' evolutionary trajectories. At the smallest scale, I address the problem through studies of the spatial packing of desert ant colonies in deserts of North America and Australia. At a larger scale, I am interested in how these interactions affect the biogeographic distribution of species. My work here has focused on reptiles on islands in the Sea of Cortez, islands in the South Pacific and off Southern Australia, and habitat fragments surrounded by urbanized areas in Southern California. Part of this work involves assessing extinction rates and the processes affecting their magnitude. I use data on the fates of historical introductions of birds, lizards, and plants to determine how species interactions and innate features of individual species and islands affect colonization success rates. One ongoing research project deals with the "house geckos" of  islands in the tropical Pacific. A sexual species has been sweeping across the Pacific over the last 50 years, displacing previous species occupying this niche. Our experiments in Fiji and Hawaii seek to uncover the mechanism behind this invader's success and the general ramifications for other systems where exotic invaders present challenges to native species. 

         The role of species interactions in patterns of evolutionary change is addressed through phylogenetic reconstructions of species groups from DNA sequence data. The pattern of important morphological and behavioral characters influential in species interactions can then be traced through the phylogeny. The role of species interactions in selecting for certain characters can be determined by comparing evolutionary trajectories of species in sympatry with those in allopatry. This approach is being used to examine the coevolution of body size among whiptail lizards in Mexico, day geckos in the Indian Ocean, and chuckwallas on islands in the Sea of Cortez. 

         The conservation of several species of local amphibians and reptiles demands a better understanding at the spatial scale of man-modified landscapes. The abundance of individual species over a mosaic of natural and man-modified habitats is poten-tially determined by small scale habitat variables (e.g., at the scale of the home range of a single individual) and more regional level effects like location on the coast/interior axis, habitat fragment size, isolation, and fire history. Are the local variables more or less successful than the regional variables in predicting the abundance and distribution of these species? How are movement patterns affected by the habitat mosaic? This project entails detailed habitat mapping of habitat variables at the local and regional scale combined with intensive studies of the abundance, movement, and recruitment of the animals using these habitats.

Learn more about books by Ted Case

         Case, T. J., M.L. Cody, and E. Ezcurra (eds). (2002). A new island biogeography of the Sea of Cortés. Oxford University Press, New York.

         Case, T.J. and M.L. Taper. (2000). Interspecific competition, gene flow, environmental gradients, and the coevolution of species borders. Amer. Natur. 155: 583-605.

         Suarez, A.V., D. A. Holway, and T. J. Case. (2001). Patterns of spread in biological invasions: lessons from Argentine ants. Proc. Natl. Acad. Sci., 98: 1095-1100.

         Radtkey, R. Fallon, S.M. and T.J. Case. (1997). Character displacement in some Cnemidophorus lizards revisited: a phylogenetic analysis. Proc. Natl. Academy of Sciences 94: 9740-9745.

         Petren, K. and T. J. Case. (1997). A phylogenetic analysis of body size evolution and biogeography in chuckwallas (Sauromalus) and other iguanines. Evolution 51: 206-219.
        Ted Case received his Ph.D. from UC Irvine and performed postdoctoral work at UC Davis. His expeditions to the Gulf of California and the Canary Islands were funded by the National Geographic Society and his research on desert ants and Pacific lizards by the NSF. His work on habitat fragmentation in southern California has been funded by a wide range of agencies including NSF and California Department of Fish and Game. He has served on the editorial boards of the journals American Naturalist, Ecology, Evolution, Evolutionary Ecology Research, Biological Invasions, and Oecologia.