INVESTIGATING PHYLOGENETIC PATTERNS OF PALM PHYTOLITH MORPHOLOGY AND APPLICATIONS FOR RECONSTRUCTING THE PALEOECOLOGY OF THE ARECACEAE
LAVIN, Samuel1, MARKHAM, Andrew1, BRIGHTLY, William2, CRIFÒ, Camilla3, GALLAHER, Timothy J.2, LOWE, Alex4, NOVELLO, Alice4, STILES, Elena2, WILSON, Paige5 and STROMBERG, Caroline A.E.6, (1)Department of Biology, University of Washington, Life Sciences Building (LSB), Box 351800, Seattle, WA 98195-1800, (2)Department of Biology, University of Washington, Life Sciences Building (LSB), Box 351800, Seattle, WA 98195-1800; Burke Museum of Natural History & Culture, University Of Washington, Box 353010, Seattle, WA 98195-3010, (3)Burke Museum of Natural History & Culture, University of Washington, Box 353010, Seattle, WA 98195-3010; Institut des Sciences de l’Evolution de Montpellier, PSL Research University, 1093-1317 Route de Mende, Montpellier, 34095, France; Department of Biology, University of Washington, Life Sciences Building (LSB), Box 351800, Seattle, WA 98195-1800, (4)Burke Museum of Natural History & Culture, University of Washington, Box 353010, Seattle, WA 98195-3010; Department of Biology, University of Washington, Life Sciences Building (LSB), Box 351800, Seattle, WA 98195-1800, (5)Department of Biology, University of Washington, Life Sciences Building (LSB), Box 351800, Seattle, WA 98195-1800; Department of Earth and Space Sciences, University of Washington, 4000 15th Ave NE, Box 351310, Seattle, WA 98195-1310; Burke Museum of Natural History & Culture, University Of Washington, Box 353010, Seattle, WA 98195-3010, (6)Department of Biology, University of Washington, Life Sciences Building (LSB), Box 351800, Seattle, WA 98195-1800; Burke Museum of Natural History & Culture, University of Washington, Box 353010, Seattle, WA 98195-3010
Palms (family Arecaceae) are an abundant and informative group in the fossil record. Palm fossils have traditionally been used as indicators of warm and wet environments, given that 90% of modern species are concentrated in tropical rainforests, and most cannot survive extended periods of freezing temperatures. Nevertheless, some palm lineages persist in relatively extreme climates, and recent paleobotanical work suggests that palms may have played an important role in biomes other than tropical rainforests in the past. Determining the taxonomic and ecological affinities of fossil palms therefore provides vital clues to the evolutionary and ecological history of Arecaceae.
Palms have a rich record of macrofossils and pollen, as well as phytoliths. These silica micro-structures form in plant tissues and can be diagnostic of particular taxonomic groups. At the family level, palm phytolith morphology is generally well-characterized. However, phytolith shape variation within Arecaceae is less well understood, including how it might correlate with phylogeny and ecology. Our research seeks to quantify this variability in modern palms, and determine whether it carries phylogenetic or environmental signals. We hope to apply the results to fossil phytoliths to infer taxonomy/ecology of ancient palms, to better understand the evolution and paleoecology of the Arecaceae. To achieve this goal, we imaged phytoliths (~30 images/species) from 82 modern palm species and 13 outgroups using confocal microscopy. Several digital measurements were taken on each phytolith, and analyzed using multivariate analysis to discriminate between different taxonomic (subfamily, tribe) and eco-taxonomic groups. Preliminary results showed moderate success in correctly assigning phytoliths to palm subfamily and tribe, and in identifying phytoliths produced by lineages not adapted to the warm and wet environments which Arecaceae typically indicates. Our plan is to use our findings to develop a model to infer the taxonomy and ecology of ancient palms based on fossil palm phytoliths, enhancing the utility of palm phytoliths as paleoenvironmental indicators.
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