Intra-specific variation in lichen secondary compounds across environmental gradients on Signy Island, maritime Antarctic

Abstract Lichens produce various carbon-based secondary compounds (CBSCs) in response to abiotic conditions and herbivory. Although lichen CBSCs have received considerable attention with regard responses UV-B exposure, very little is known about intra-specific variation across environmental gradients their role protection against herbivory the Antarctic. Here we report on of two widely distributed common Antarctic lichens, Usnea antarctica Umbilicaria , between sites different solar exposure (NW–SE) along natural nitrogen (N) which are associated changing lichen-invertebrate associations Signy Island (South Orkney Islands, maritime Antarctic). Fumarprotocetraric usnic acid concentrations showed no relationships lichen-N or invertebrate abundance. However, fumarprotocetraric concentration was 13 times higher at inland compared coastal N-gradients. Gyrophoric 33% lower sun-facing (northerly exposed) habitats more shaded (south-facing) rocks declined elevation. positively correlated abundance species richness microarthropods, similar patterns found N. This initial investigation indicates that there can be large intraspecific CBSC relative short distances (< 500 m) raises further questions regarding current understanding lichens relation biotic pressures.