100 Influential Papers - page 29

S P EC I E S I NT E RACT I ONS
Paine, R. T. (1980)
Food webs: linkage, interaction strength and community infrastructure.
Journal of Animal Ecology, 49, 666-685.
Bob Paine delivered this paper as the 3rd Tansley Lecture so he could fly a few kites without fear, leaving a ripe field of intriguing ideas and
concepts for exploration by the rest of us. Thanks, Bob. From empirical data collection, Bob showed that the vast majority of interactions
in food webs are very weak, with only one or two strong interactions that keep aggressive competitors in check and allow weakly linked
species to develop as co-evolved modules. This was the first plausible explanation for the lumpy structure of interaction
webs that promoted stability in model ecosystems described earlier by May. It was exciting to see field work and theory
coming together.
Furthermore, Bob Paine showed unequivocally that these strong interacters can only be identified through
manipulative field experiments. Simply documenting who eats whom, or even quantifying energy moving
between prey and predator will not reveal those linkages which are functionally important. In his food web
there is insignificant energy moving along the sea urchin-kelp linkage, but remove the sea urchin and everything
comes tumbling down. As testimony to the paper’s inspirational effect, I spent the next 15 years repeating
Bob’s approach in an estuarine food web and found the same things: it didn’t take Bob half as long!
Dave Raffaelli
57
Atkinson, W.D. and Shorrocks B. (1981)
Competition on a divided and ephemeral resource:
a simulation model.
Journal of Animal Ecology,
50, 461-471.
The question, “How do species coexist?” has taxed ecologists
for centuries. Classical models state that stable coexistence is
possible if the strength of intraspecific competition exceeds that
of interspecific competition. But in what ecological scenarios
could that occur? Motivated by
Drosophila
fruitflies exploiting
patchy food resources, Atkinson & Shorrocks noted that
clustering of species could provide opportunities for inferior
competitors to grow in the absence of dominants. The dominants
would (on average) find themselves fighting among themselves,
elsewhere. To test this, Atkinson & Shorrocks developed one
of the best-known early ecological examples of a simulation
model. They exploited burgeoning computer processing power
to simulate aggregated distributions of competing species across
food patches, and measured duration of coexistence. Aggregation
did indeed promote coexistence. Less robust was speculation
that coexistence could emerge from random selection of patches
by egg-laying females. This paper joins the list of 100 influential
papers for three main reasons. First, it clarified the role of
aggregation in promoting coexistence among species. Second,
it promoted the use of simulation modelling as a new weapon in
the armoury of ecological research. Third, its conclusions were
not without controversy: debate surrounding the ecological
mechanisms that promote aggregative coexistence rages on.
David Hodgson
58
Cornell, H.V. & Lawton, J.H. (1992)
Species interactions, local and regional processes,
and limits to the richness of ecological communities:
a theoretical perspective.
Journal of Animal Ecology,
61, 1-12.
The relationship between the species richness of local
assemblages and the species richness of the regional assemblages
in which they are embedded is a fundamental ecological pattern.
Regional richness must obviously equal or exceed local richness,
but given that constraint a wide variety of relationships remain
possible. This paper is significant in that it brought to wide
attention the importance of understanding local-regional richness
relationships; reviewed the theoretical evidence for the different
forms these relationships might take; and established some of
the core terminology to be used when discussing them (e.g. the
distinction between Type I ‘unsaturated’ and Type II ‘saturated’
relationships). Importantly, it argued that local assemblages are
typically unsaturated with species (residents do not inevitably
exclude invaders), that Type I relationships are likely to be
widespread, and that the principal direction of control is from
regional to local species richness. These assertions have all
subsequently been much debated, and the relative role of local and
regional processes in shaping local species assemblages, and how
this changes in time and space, remains contentious. In opening
up this discussion this paper arguably gave a much needed boost
to the development of the field of macroecology, which was
established on the premise that regional ecological patterns and
processes were fundamentally important, and that ecology needed
to pay more attention to them.
Kevin Gaston
59
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