Sprecher
Beschreibung
This presentation explores how temperature variation influences Fourier Transform Infrared (FTIR) spectra of sporopollenin, and the implications for palaeoecological and taxonomic research. Previous studies on fresh pollen have shown that climatic conditions during pollen’s formation leave a measurable imprint on FTIR spectra, with heat stress producing distinct chemical changes. However, the extent to which temperature affects the chemistry of sporopollenin, the resistant outer wall of pollen grains that lacks any organic compounds, remains poorly understood.
To address this, seeds of Microseris walteri (Asteraceae) and Anthosachne scabra (Poaceae) from the Australian National Seed Bank, together with Hordeum murinum (Poaceae) from the Royal Botanic Gardens, Kew, were cultivated under three controlled climate scenarios representing environmental conditions in southern Australia: warm (27°C), intermediate (20°C), and cold (16°C). Pollen from each taxon was analysed using FTIR spectroscopy to identify temperature-related variations in absorbance, and these trends were compared with herbarium specimens of the same taxa collected under differing bioclimates.
Results show consistent temperature-driven changes in absorbance at several wavenumbers associated with sporopollenin chemistry. Similar spectral trends were observed in both experimentally-grown and herbarium-collected pollen. These environmental influences may partially obscure species-specific taxonomic signals and contribute to classification patterns. However, Random Forest classification models indicated that classification errors could not be explained solely by temperature effects. Overall, this study highlights the importance of accounting for environmental variation when interpreting pollen FTIR spectra. It also demonstrates the value of integrating experimental growth studies, which enable us to track how environmental signals interfere with the taxonomic signature.