Agriculture Reference
In-Depth Information
3
Planetary Processes and Their
Interactions with Earthworm
Distributions and Ecology
Samuel W. James
Department of Life Sciences, Maharishi University of Management,
Fairfield, Iowa, U.S.A.
CONTENTS
Studies of the history of earth are traditionally the domain of geologists and those in various
paleodisciplines (paleontology, paleoecology, paleoclimatology, paleobotany, etc.). However, the
history of biology has many examples of research into the connections between present-day
biogeography and ecology on the one hand and earth history on the other. Such research may be
considered in three broad categories. First, there is application of data derived from life forms of
the present to questions of earth history. For example, the use of phylogenetic trees in combination
with distributional data can provide valuable insights into the history of land-area relationships, as
in the field of vicariance biogeography, which studies processes that split distributions (vicariating
events) in relation to phylogeny (Wiley 1988).
It may be claimed that earthworms were of some importance in the early development of plate
tectonic theory and, therefore, of vicariance biogeography, because the former discipline has been
very important to the ascendance of the latter. Plate tectonics theory attempts to account for the
movement of parts of the EarthÔs crust and provides a means of recovering the ancient positions
of those crustal pieces.
The Oligochaete systematist Michaelsen (1933) named an earthworm genus after Wegener in
honor of WegenerÔs work toward understanding the distributions of earthworms. It is possible that
the two men (who were office neighbors at the University of Hamburg) discussed earthworm
distributions, providing Wegener with more evidence for his theory, which was radical at the time.
Many other groups of organisms have been used in arguments supporting or refuting various
hypotheses about the history of events (Rosen 1985; Humphries and Parenti 1999; Liebherr 1988).
One can also find a significant thread of research to trace the contributions of living organisms
to global processes. In its boldest version, this area is termed the Gaia hypothesis (Lovelock 1988),
but numerous more mundane examples can be found in the literature on biogeochemical cycles,
trace gas fluxes, and many other topics relevant to global climate models.
For example, earthworms may influence landforms. Charles Darwin (1881) described a process
by which earthworms could increase rates of soil erosion and thereby the rates of change of land
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