The spatial ecology of Galapagos tortoises and New Mexico's reptiles

The analysis of spatial processes and spatial heterogeneity is an important part of ecology because distribution of organisms in space partly defines ecology as a discipline. In addition, advances in analysis of DNA, geographical computing and the availability of vast amounts of environmental data obtained by satellites provide new opportunities for studying ecology at different spatial and phylogenetic scales. My research takes advantage of information gathered by satellites and adds modeling and data collected on the distribution of different reptiles to examine processes at various spatial and temporal scales. In Chapter 1 I describe how juvenile Galapagos tortoises change their patterns of distribution as they grow. These patterns relate to different levels of productivity of vegetation, but that relationship is only evident for older juveniles. In Chapter 2, I examine body sizes in different taxa of Galapagos tortoises from an evolutionary and ecological perspective. While body sizes of adults of different taxa of tortoises covary with primary productivity, I did not find any association between body size and phylogeny of these tortoise taxa. In Chapter 3 I develop and field-test a method for modeling the potential distribution of species. I focus on reptiles in New Mexico and describe a multivariate technique that allows comparison of the suitability of landscape for different species between different areas. Maps produced with this method can be used for planning inventory and monitoring of species at coarse spatial scales and can help in identifying conservation opportunities.