Abstract Detail

Paleobotany

Armos, Bailey [1], Lavin, Sam [1], Akbar, Sultan [2], Brightly, William [2], Crifò, Camilla [1], Gallaher, Timothy [1], Lowe, Alex [1], Novello, Alice [1], Wilson, Paige [4], Strömberg, Caroline [1].

The utility of palm phytoliths for inferring the evolution and paleoecology of Arecaceae.

Palms (family Arecaceae) are well represented in the fossil record, particularly because they are prolific producers of microscopic silica bodies (phytoliths), which are formed in the living plant tissues. After a plant dies and decays, phytoliths are incorporated into the soil or sediment where they can be preserved as fossils. Importantly, phytoliths are preserved in many environments where leaf impressions and other macrofossil are absent. Fossil palms have traditionally been considered to be reliable indicators of warm, equable conditions based on their current distribution. Today, over 90% of palm species diversity is concentrated in tropical rainforests and most palm taxa cannot tolerate prolonged periods of freezing temperatures. However, certain palm lineages nevertheless persist in relatively extreme climates, and recent paleobotanical work suggests that these palms may have played an important role in biomes other than tropical rainforests in the past. Being able to determine the taxonomic affinities of fossil palm phytoliths would therefore provide vital clues to the evolutionary and ecological history of Arecaceae. Unfortunately, palm phytolith taxonomy is currently poorly constrained below the family level. As a consequence, we know very little about how much taxonomical and ecological information can be inferred from palm phytolith morphological features. The objective of our work is to test whether palm phytoliths can be placed to subfamily or generic level within Arecaceae using a morphometric approach. To do so, we extracted phytoliths from herbarium specimens using standard extraction procedures and mounted them on slides for observation and imaging under a confocal microscope. Morphometric analysis was performed on phytolith images from 100 species of Arecaceae (~30 images/species) using a semi-automated script in Image J that quantifies phytolith overall shape and size as well as the density, shape, and size of phytolith ornamentations. This measurement protocol was successfully tested on a set of artificially generated palm-like 2-D shapes that differed in their main size and shape features. We also collected data on species habitat, climate, and ecology, and used phylogenetic comparative methods to test for biogeographical, phylogenetic and ecological signal in palm phytolith morphology. Our results shed light on the taxonomic resolution of palm phytoliths and ultimately on their utility in reconstructing Arecaceae evolutionary history and in paleoenvironmental inference.

1 - University Of Washington, Biology, 24 Kincaid Hall, Box 351800, Seattle, WA, 98195, United States
2 - University Of Washington, Biology, 24 Kincaid Hall, Box 351800, Seattle, WA, 98195, USA
3 - University Of Washington, Biology, 24 Kincaid Hall, Box 351800, Seattle, WA, 98195, United States
4 - University Of Washington, Department of Earth and Space Sciences, Johnson Hall Rm-070, Box 351310 , 4000 15th Avenue NE, Seattle, WA, 98195, United States

Keywords:
fossil
paleobotany
Phytolith
palms
Arecaceae
geometric morphometrics.

Presentation Type: Poster
Session: P, Paleobotany Posters
Location: Arizona Ballroom/Starr Pass
Date: Monday, July 29th, 2019
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PPB004
Abstract ID:865
Candidate for Awards:None