Meeting Abstract

P2.98  Saturday, Jan. 5  Patterns of Abiotic Niche Evolution in Salamanders Along Different Niche Axis Spatial Scales GAUDREAU, M.G.*; BERGMANN, P.J.; Clark University, Worcester, MA; Clark University, Worcester, MA mgaudreau@clarku.edu

Niche evolution, or the tendency for ecological traits to diverge over time, is a process that can produce numerous patterns of niche trait distribution. These patterns may ultimately show how species distributions change in response to environmental changes, and how they diversify. Niche evolution occurs along course scale axes such as biome type and climatic attributes, and along increasingly finer scale axes such as habitat and microhabitat. Rates and modes at which course and finer scale niche axes evolve are likely to differ because of differing spatial heterogeneity of the underlying environmental variables. Here, we test whether courser scale niche axes display patterns of greater niche conservatism than finer scale niche axes. We quantified several abiotic niche axes of varying spatial scale (biome, canopy height, altitude, latitude, temperature, precipitation, and various aspects of the habitat and microhabitat) for over 300 species of adult salamanders. We used Pagel’s κ, δ, and λ parameters to characterize patterns of niche evolution for each axis. We used κ to quantify the degree of gradual evolution for each niche axis, δ to determine whether most evolution along each niche axis occurred near the base of the tree (suggesting adaptive radiation) or the tips of the tree, and λ to evaluate whether changes in niche axes coincided with phylogenetic relationships of salamanders. We also estimated the Brownian Motion rate parameter, σ, to compare rates of niche axis evolution at different spatial scales. To our knowledge, this is the first investigation of the evolution of numerous detailed abiotic niche axes along different spatial scales in a large clade of organisms.