Abstract Detail



Ecology

Simpson, Andrew [1].

Fleshy propagules do not necessarily mean animal-dispersed seeds: experimental data from Ginkgo biloba.

Animal seed dispersal is a widespread trait in angiosperms, and has been implicated as important in the diversification and survivorship of plant taxa over geologic time. This difference between the common, “classic” dispersal mode in angiosperms versus that of the non-animal-dispersed gymnosperms has been suggested to partially explain how angiosperms have succeeded gymnosperms both in diversity and in ecological prominence. Not all gymnosperms lack animal dispersal; for example, the Pinaceae are cached by rodents and birds. These lineages of gymnosperms possessing animal dispersal are also often still diversifying, alongside angiosperms.
In this experiment, I test this assertion using Ginkgo biloba. Perhaps the most iconic gymnosperm lineage that is in decline, the genus Ginkgo has experienced massive range collapse since its appearance in the lower Jurassic, and many other related ginkgophytes once existed, but have all become extinct. Living G. biloba has large, aromatic, fleshy seeds that suggest animal dispersal, but these seeds contain chemicals unpalatable to some ordinarily fruit-loving mammals. Instead, Ginkgo is suggested to have once been dispersed by now-extinct dinosaurs, and that the extinction of its dispersal agents is responsible for its decline. Although today the native range of living G. biloba is in western China, the genus is widespread in the North American fossil record, especially in floras that resemble today’s eastern deciduous forest.
I set out thirty seeds of G. biloba along a transect, each attached by a 1m length of sewing thread to electric flagging tape, intending to track their movement by animal dispersers (if any) using the flagging tape. I conduct two experiments, one in the fall with the fleshy sarcotestas in place and the second in the spring with the sarcotestas removed over one month. The fall experiment did not see a single seed removed by frugivores or granivores. The spring experiment has been delayed by cold weather, but full results will be ready in time for the meeting. Preliminary data suggest that living Ginkgo lacks animal dispersal despite its large, fleshy seeds. Macroecologists and paleobotanists should be cautious inferring animal dispersal from size of seeds.


1 - Department Of Paleobiology, National Museum Of Natural History, Smithsonian Institution, Washington, DC, 20560, United States

Keywords:
seed dispersal
Ginkgo
Field study.

Presentation Type: Oral Paper
Number: 0004
Abstract ID:428
Candidate for Awards:None


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