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Abstract Detail


Brightly, William [1], Stromberg, Caroline [2].

Building a Quantitative Framework for Assessing Seed Dispersal Syndrome in Grasses During the Cenozoic Spread of Grasslands.

Seed dispersal is a critical stage in the lifecycle of many plants, with wide-ranging impacts on recruitment, population connectivity, and community composition. In modern ecosystems, dispersal syndrome is often strongly influenced by vegetation structure or ecological role. Major vegetation shifts are therefore expected to have major impacts on dispersal strategy within plant communities. The evolution of grasslands during the mid-late Cenozoic constitutes such a major shift, but little is known about how grass reproductive ecology changed during this transition.
To shed light on this, we explore a number of morphological traits linked to seed dispersal in modern and fossil grasses, to establish an interpretive framework for seed dispersal syndrome. We focus primarily on quantifying surface roughness, mass, and settling velocity to establish a gradient from taxa with ideal properties for wind dispersal to those better suited for animal dispersal (both internal and external). We then apply these metrics to silicified anthoecia from the Oligocene-Miocene of the North American Great Plains. This time interval saw dramatic restructuring of the region, including the initial expansion of grass dominated habitats, subsequent increases in openness, and eventually the establishment of C4 dominated floras. Studying the aforementioned traits in fossil grasses will allow us to assess whether the wide range of morphological variation observed in the fossil record of grass anthoecia corresponds to any functional differences in dispersal strategy, and how these differences relate to coeval changes in vegetation structure and grass ecology.
Initial work has focused on building a reference collection of modern grasses. This dataset includes grasses of known dispersal strategy (e.g., Cenchrus longispinus, Cortaderia selloana), the nearest living relatives of fossil taxa (e.g., Piptochaetium spp., the closest extant relatives of species in the fossil genus Berriochloa), and grasses from extant ecosystems of interest (e.g., common taxa of the present day Great Plains). Initial results suggest good discrimination between taxa with high potential for adhesive, internal, and wind dispersal. Methods for incorporating fossil taxa into this morphospace have also been established. In addition, efforts are being made to evaluate dispersal by other vectors. Ultimately, reconstructing critical aspects of the reproductive ecology of Cenozoic grasses will contribute to a more complete understanding of the patterns and processes associated with the initial establishment of grass dominated ecosystems in North America.

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1 - 2208 NW 64th St, Seattle, WA, 98107, United States
2 - University Of Washington, Department Of Biology, 24 Kincaid Hall, Box 351800, Seattle, WA, 98195, United States

seed dispersal
Great Plains.

Presentation Type: Oral Paper
Session: 28, Cookson Award Session I
Location: 109/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 3:00 PM
Number: 28007
Abstract ID:948
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award

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