Kellogg, Derek , Klavins, Sharon D. , Taylor, Thomas N. , Taylor, Edith L. .
Were early cycads insect pollinated?.
Insect pollination in extant cycads is well documented and is thought to be an ancient interaction, perhaps even older than the relationship between insects and angiosperms. Modern cycads are pollinated primarily by beetles and, as such, it has been suggested that this association has its roots as far back as the early Mesozoic or late Paleozoic. Here we present an example of pollinivory on Middle Triassic cycad pollen sacs from Antarctica. The pollen cone Delemaya has helically arranged microsporophylls which bear pollen sacs on the abaxial surface. Pollen is small (~20 μm long), monocolpate, psilate, and morphologically similar to modern cycad grains. Small (120 μm by 60 μm), roughly cylindrical coprolites comprised entirely of pollen from Delemaya are associated with, and interspersed among, the disaggregated pollen sacs. The shape and size of the coprolites resemble the fecal pellets of extant insects. To date, we see no evidence of pollinivory among sacs attached to microsporophylls of the intact cone. The presence of these coprolites within cycad pollen sacs and the morphology of the pollen and coprolites suggests a plausible hypothesis in which this represents a stage in the evolution of insect pollination. It is likely that this interaction evolved early in the history of these gymnospermous seed plants and has remained relatively unchanged until the present.
1 - University of Kansas, Dept. of Ecology and Evolutionary Biology, 1200 Sunnyside Avenue, Lawrence, Kansas, 66045-7534, U.S.A.
Presentation Type: Paper
Location: Maybird (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 9:15 AM