Abstract Detail

Systematics Section/ASPT

Oberle, Brad [1], Stevens, Peter [2], Zanne, Amy [1].

Ecological asymmetries and biosphere evolution, or, small is beautiful clade-wise.

The metric most commonly used to evaluate success is species number, indeed, other data are hard to come by. However, available estimates of measures like primary productivity and especially above- and below-ground carbon sequestration paint a different picture of biome evolution. Members of a few relatively small clades largely other than asterids dominate considerable areas of the earth’s surface, often in more or less extreme conditions outside tropical rainforest. Examples are angiosperms living in mangrove, marine and estuarine conditions,, those with C4 photosynthesis, and seed plants with ecto- and ericoid mycorrhizae. Thus marine angiosperms, a mere 55 species, are responsible for ca 20% of total marine C storage, and ectomycorrhizal taxa dominate in boreal and many temperate forests, large areas of Africa, and Indo-Malesian forests. In such communities carbon sequestration is massive and often in the thousands of years. Add changes in wood formation, stomatal functioning, and venation density, and seed plants in general may have driven major elements of biosphere evolution, in particular, changes in atmospheric CO2 concentration, rainfall, and rock and soil weathering regimes. Integrating such aspects of seed-plant evolution with historical changes is a challenge; dating the clades involved may be easier than evaluating their historical roles. Thus grasslands and their unique C-sequestering mollisols are recent (<10 m.y.), but the origin of C4 photosynthesis can de dated to 20 m.y. or so earlier, and while at least some ectomycorrhizal associations are still older, understanding their ecological history is more difficult. But thinking about such aspects of evolution, one may well ask, do seeds, flowers, and species numbers really matter?

Broader Impacts:

Related Links:
Angiosperm Phylogeny Website

1 - George Washington University, Department of Biological Sciences, Washington, DC, 20052, USA
2 - University of Missouri at St Louis and Missouri Botanical Gardens, Department of Biology, St Louis, MO, USA

Keywords:
seed plants
biosphere evolution.

Presentation Type: Oral Paper:Papers for Sections
Session: 18
Location: Magnolia/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 10:15 AM
Number: 18007
Abstract ID:659
Candidate for Awards:None