Geoscience Reference
In-Depth Information
(
Cohen et al., 2003; Digel et al., 2011; Leaper and Huxham, 2002; Layman
et al., 2005; McLaughlin et al., 2010; O'Gorman and Emmerson, 2010; Otto
et al., 2007
; Riede et al., 2011;
Romanuk et al., 2011; Sinclair et al., 2003;
Yvon-Durocher et al., 2008
). In conjunction with the strong negative rela-
tionship between species body mass and abundance found in many systems,
researchers are beginning to integrate these patterns, with the aim of unifying
much of food web theory with other approaches, such as the metabolic
theory of ecology and foraging theory, to create a framework that can span
multiple levels of ecological organisation, from individuals through to entire
multispecies networks (
Brose, 2010; Brown and Gillooly, 2003; Brown et al.,
2004; Cohen et al., 2003; Thierry et al., 2011; Woodward et al., 2010, Yvon-
Durocher et al., 2011
).
B. Overcoming Pitfalls Through a Plurality of Viewpoints
Although many of the studies of the allometry of trophic relations have
detected clear patterns between body size and food web structure (e.g. a
tendency for diet width to expand with predator size, both within and
among predator species;
Cohen et al., 1993; Woodward and Hildrew,
2002
), there have been concerns raised about whether the patterns reflect
the reality of interactions between individuals in any given system (
Yvon-
Durocher et al., 2011
). Studies that have used regional data compiled from
multiple systems may reveal patterns in interactions that would not in fact be
seen at the local scales, dislocating such patterns from the individual-level
mechanisms underlying the size structure of trophic relations (
Woodward
and Warren, 2007
). This concern is in many regards similar to that raised by
researchers investigating the relationship between body size and abundance.
In that case, there have been reports of strong macroecological relationships
discovered in global datasets (often considering just one clade), while studies
at the local community scale (and across clades) often find a different pattern
and sometimes none at all, raising queries as to which patterns are mechanis-
tically driven and which are the result of artefacts (
White et al., 2007
).
Further, studies of mass-abundance relationships also highlight the his-
toric divide between aquatic and terrestrial ecology and illustrate how the
approaches developed in each, when unified, can yield complementary infor-
mation about ecosystem structure (
Ings et al., 2009
and references therein).
Aquatic ecologists have long used individual size distributions in which
species identity is ignored to investigate mass-abundance relationships
(
Kerr and Dickie, 2001
), whereas terrestrial ecologists have more often
looked at the local species density relationship in which species-averaged
masses are used (i.e. ignoring intraspecific differences) (
McLaughlin et al.,
2010; Mulder et al., 2005
). Essentially, there is more than one way to examine
