SINCLAIR, BJ*; KLOK, CJ; TERBLANCHE, JS; SCOTT, MB; CHOWN, SL; Univ. Nevada, Las Vegas; Arizona State University; Univ. of Stellenbosch, South Africa; Univ. of Otago, New Zealand; Univ. of Stellenbosch, South Africa: Physiological constraints on the small-scale distribution of three species of Antarctic Collembola

We investigated the tolerance to cold, heat and desiccation of three species of Collembola, Isotoma klovstadi, Cryptopygus cisantarcticus (Isotomidae) and Friesea grisea (Neanuridae), at Cape Hallett, North Victoria Land, Antarctica. C. cisantarcticus was less tolerant of low and high temperatures and of desiccation than the other two species. We observed that the three species were spatially segregated, and this was borne out in a model of distribution from a systematic survey that incorporated spatial terms. Microclimate temperature recordings from representative microhabitats indicate that the habitat occupied by I. klovstadi has temperatures that regularly cross both the upper and lower survival thresholds of C. cisantarcticus, and we propose that the spatial segregation of the Collembola species at Cape Hallett may be mediated by their environmental tolerances.