{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T13:58:37Z","timestamp":1768485517377,"version":"3.49.0"},"posted":{"date-parts":[[2019,9,9]]},"group-title":"Ecology","reference-count":70,"publisher":"openRxiv","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2019,11,19]]},"abstract":"vi.<\/jats:label>\n Abstract<\/jats:title>\n \n Aim<\/jats:title>\n \n Fossil pollen is an important tool for understanding biogeographic patterns in the past, but the taxonomic resolution of the fossil-pollen record may be limited to genus or even family level. Chemical analysis of pollen grains has the potential to increase the taxonomic resolution of pollen, but present-day chemical variability is poorly understood. This study aims to investigate whether a phylogenetic signal is present in the chemical variations of\n Quercus<\/jats:italic>\n L. pollen and to assess the prospects of chemical techniques for identification in biogeographic research.\n <\/jats:p>\n <\/jats:sec>\n \n Location<\/jats:title>\n Portugal<\/jats:p>\n <\/jats:sec>\n \n Taxon<\/jats:title>\n \n Six taxa (five species, one subspecies) of\n Quercus<\/jats:italic>\n L.,\n Q. faginea, Q. robur, Q. robur<\/jats:italic>\n ssp.\n estremadurensis, Q. coccifera, Q. rotundifolia<\/jats:italic>\n and\n Q. suber<\/jats:italic>\n belonging to three sections:\n Cerris, Ilex<\/jats:italic>\n , and\n Quercus<\/jats:italic>\n (Denk, Grimm, Manos, Deng, & Hipp, 2017)\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n We collected pollen samples from 297 individual\n Quercus<\/jats:italic>\n trees across a 4\u00b0 (\u223c450 km) latitudinal gradient and determined chemical differences using Fourier-transform infrared spectroscopy (FTIR). We used canonical powered partial least-squares regression (CPPLS) and discriminant analysis to describe within- and between-species chemical variability.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n We find clear differences in the FTIR spectra from\n Quercus<\/jats:italic>\n pollen at the section level (\n Cerris<\/jats:italic>\n : \u223c98%;\n Ilex<\/jats:italic>\n : \u223c100%;\n Quercus<\/jats:italic>\n : \u223c97%). Successful discrimination is based on spectral signals related to lipids and sporopollenins. However, discrimination of species within individual\n Quercus<\/jats:italic>\n sections is more difficult: overall, species recall is \u223c76% and species misidentifications within sections lie between 18% and 31% of the test-set.\n <\/jats:p>\n <\/jats:sec>\n \n Main Conclusions<\/jats:title>\n \n Our results demonstrate that subgenus level differentiation of\n Quercus<\/jats:italic>\n pollen is possible using FTIR methods, with successful classification at the section level. This indicates that operator-independent FTIR approaches can surpass traditional morphological techniques using the light microscope. Our results have implications both for providing new insights into past colonisation pathways of\n Quercus<\/jats:italic>\n , and likewise for forecasting future responses to climate change. However, before FTIR techniques can be applied more broadly across palaeoecology and biogeography, our results also highlight a number of research challenges that still need to be addressed, including developing sporopollenin-specific taxonomic discriminators and determining a more complete understanding of the effects of environmental variation on pollen-chemical signatures in\n Quercus<\/jats:italic>\n .\n <\/jats:p>\n <\/jats:sec>","DOI":"10.1101\/761148","type":"posted-content","created":{"date-parts":[[2019,9,10]],"date-time":"2019-09-10T00:54:08Z","timestamp":1568076848000},"source":"Crossref","is-referenced-by-count":0,"title":["Chemical variations in\n Quercus<\/i>\n pollen as a tool for taxonomic identification: implications for long-term ecological and biogeographical research"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1242-7381","authenticated-orcid":false,"given":"Florian","family":"Muthreich","sequence":"first","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5046-520X","authenticated-orcid":false,"given":"Boris","family":"Zimmermann","sequence":"additional","affiliation":[]},{"given":"H. John B.","family":"Birks","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4285-8008","authenticated-orcid":false,"given":"Carlos M.","family":"Vila-Vi\u00e7osa","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8266-0947","authenticated-orcid":false,"given":"Alistair W.R","family":"Seddon","sequence":"additional","affiliation":[]}],"member":"54368","reference":[{"issue":"3","key":"2019112113391142000_761148v2.1","doi-asserted-by":"crossref","first-page":"1199","DOI":"10.1111\/gcb.13487","article-title":"Landscape dynamics in Mediterranean oak forests under global change: Understanding the role of anthropogenic and environmental drivers across forest types","volume":"23","year":"2017","journal-title":"Global Change Biology"},{"key":"2019112113391142000_761148v2.2","first-page":"191","volume-title":"The Vegetation of the Iberian Peninsula","volume":"1","year":"2017"},{"issue":"7","key":"2019112113391142000_761148v2.3","doi-asserted-by":"crossref","first-page":"870","DOI":"10.1111\/2041-210X.12697","article-title":"Monitoring of plant\u2013environment interactions by high-throughput FTIR spectroscopy of pollen","volume":"8","year":"2017","journal-title":"Methods in Ecology and Evolution"},{"key":"2019112113391142000_761148v2.4","doi-asserted-by":"crossref","unstructured":"Ba\u011fcio\u011flu, M. , Zimmermann, B. , & Kohler, A. 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