Meeting Abstract

1.2  Saturday, Jan. 4 08:15  Spatial, phylogenetic, and functional ecological perspectives on aquatic insect thermal tolerance BERNARDO, J.; Texas &M University jbernardo@tamu.edu

Aquatic insects are key ecological players in freshwater food webs. Accordingly, an understanding of their physiological tolerances to warming waters illuminates the potential responses of aquatic systems, especially streams, to climate change. I review literature data for 100+ global species to quantitatively describe patterns of thermal tolerance and to describe latitudinal, phylogenetic, or functional-ecological patterns in tolerance that may have bearing on understanding the resistance, resilience, or vulnerability of these species and their ecosystems to warming. I also report new data for 10 tropical species. There is tremendous interspecific variation in thermal tolerance within and between phylogenetic lineages (orders), and within and among functional groups. Nonetheless, a strong colinearity between functional group and order means that statistically, any effect ascribable to functional group vanishes when phylogeny is considered in the analysis. That said, the implications of the variation for tolerance to warming waters is evaluated, given the distributions of existing species traits. No striking latitudinal patterns were observed such as those that have been documented for terrestrial insects and other terrestrial ectotherms. The dominant result is that aquatic stream insects exhibit thermal tolerances that are far greater than those encountered in their habitats, indicating that it is unlikely the aquatic temperatures per se are likely to be limiting. Rather, thermal tolerance during terrestrial dispersal is most likely the venue during which physiological limitation will arise, and which is the selective mileau venue which has molded the evolution of thermal tolerance in aquatic insects.