Peter Kareiva
kareivap@zoology.washington.edu
Romanticizing the past and missing the point of the
future
I can remember the "good old days" of ecology, and
they were not so good. And when I consider what is going on currently
in ecology, I see extraordinary advances and creativity, albeit
not along the lines that were hoped for during what I consider
to be ecology's sophomoric phase. I want to make three points:
1.) the golden era of ecology that Jim refers to was actually
a naive (but necessary) step towards a more mature science
2.) it is easy to come up with recent advances in ecology every
bit as exciting as anything from between 1955 and 1975, and much
more useful
3.) the dichotomy between reductionism and synthetic science
(or the science of "complexity") is misleading and ill-posed.
The "Golden Era" or fond memories of adolescence?
As a graduate student at the end of the seventies, I was forced
to read many of the papers from between 1955 and 1975 that Jim
probably fondly remembers as pathbreaking. I am sure I remember
these papers differently than he does -- I found them lacking
in mechanism, testability, and rigor. They were like the dreams
and wishes of a teenager --- wouldn't it be cool if measuring
where warblers fed in trees for a few hours of total observation
time informed us in a serious way about warbler population interactions
and dynamics? Sure, there were lots of ideas, but what exactly
did ecology get right? What non-obvious predictions were made
and vindicated? Certainly there were 20 or more studies that
changed the course of the discipline, but what type of change
was it? I think of ecology's shift during that golden era as
something akin to the rampant biological and social upheaval that
goes on during an adolescent's teen-age years. But "growing
up" should not be equated with a loss of intellectual firepower
-- instead it reflects a sharpening of vision and focus -- and
that is exactly what has happened in ecology. Let's honestly
go back to those twenty years of ecology and review the type of
research that dominated our journals. Niche descriptions and
studies of niche overlap prevailed. Comparisons between models
and data were anecdotal, and the type of species interactions
that were studied was unduly biased towards competition. Genetic
architecture, structured populations, spatial processes, an appreciation
of the subtle ways environmental variability alters species interactions,
nonequilbrium dynamics and many more ideas we now take for granted
were all woefully neglected. Patterns of diversity, patterns
of niche overlap, patterns of plant spacing, patterns of body
size -- patterns were all the rage. But where was dynamics?
We are asking better questions with clearer thinking
and more sophisticated methods
In lieu of an emphasis on "patterns", modern ecology
is in fact concerned with dynamics and processes. This shift
changes the research agenda and the types of questions researchers
find interesting. Among the many exciting issues to be illuminated
in the last twenty years are the generation of spatial patterning
in homogenous environments because of dispersal and local nonlinearities,
the importance of age or stage structure at altering dynamics,
the interplay of genetics and ecology in controlling species interactions,
the many sources of chaos, the role of environmental variability
in promoting or preventing coexistence (depending on how that
variability influences a species' demography), the role of trophic
cascades in ecosystem dynamics, the threat of exotic species as
wholesale community perturbations, the central importance of
tradeoffs as facilitators of biodiversity, and dozens more. Instead
of asking why there are more species in the tropics than in the
temperate zone, ecologists now seek to understand what processes
maintain diversity within particular systems, and what might be
the "function" of biodiversity. Instead of asking if
patterns of niche overlap are random, ecologists now seek to predict
the vulnerability of species to habitat degradation as a result
of habitat usage. Instead of endless calculations aimed at identifying
equilibrium population densities, theoreticians now appreciate
the rich spectrum of population dynamics that never give a glimmer
of equilibrium behavior. Ecology is routinely used to mitigate
threats to endangered species, to identify prime portions of the
landscape in need of protection, to restore damaged ecosystems,
to suggest approaches for the control of exotic invaders, to provide
methods for risk analysis pertaining to genetically engineered
crops, and much more. Where was ecology in the sixties when
environmental degradation and the loss of biodiversity was already
well underway?
The so-called antagonism between reductionist science
and the synthetic science of complexity is simplistic
Of course reductionism by itself is inadequate. But very few
ecologists I know retreat totally under the blanket of reductionism.
Indeed, I wonder if what Jim Brown is calling reductionism isn't
really just a rejection of the emphasis on patterns as opposed
to dynamics. Reductionism does not imply that dynamic processes
are predictable in a simple manner. A reductionist could well-appreciate
the chaotic dynamics of nonlinear systems, and seek to understand
what aspects of the environment influenced the tendency of a system
to move towards chaos. In fact I see no connection between
the fact that systems are complex and the relative merits of reductionist
science. Why should we worry about some imagined narrowness,
when more ecologists than ever before are making connections with
economics, with risk analysis, with land management, and with
environmental policy ? Jim points out that medicine and the treatment
of immensely complicated and unpredictable human bodies must
recognize uncertainty. I agree. But this has nothing to do with
reductionism. The mistake Jim makes is to think that a reductionist
cannot deal with uncertainty, and is wedded to trying to predict
specific population densities. But this is simply not the case.
Medicine is an enormously successful reductionist enterprise,
and one mature enough to not worry about predicting when someone
might die -- instead it seeks to understand the causes of death.
Jim dreams of universal laws that will help us meet our environmental
challenges. I think we have all the universal laws we need in
ecology. Our future advances will not be concerned with universal
laws, but instead with universal approaches to tackling particular
problems, and with general theoretical insights about the surprises
that may ambush us if we think too narrowly. I am much more
worried that the pinings of senior scientists for some long-past
glorified era will distract us from our real problems, than I
am worried about the lack of fundamental progress in ecology.
NCEAS has two missions: (i) the synthesis of data and ideas
that yield new insights, and (ii) the application of ecological
theory to realworld problems. If NCEAS truly attempts to address
real problems, I am convinced theoretical ecology will be pulled
along and that original synthesis will emerge (recall what happened
in theoretical physics at Los Alamos towards the end of World
War II). The NCEAS need not worry about being cosmic -- it simply
needs to ensure that imaginative scientists are brought together
to apply theory to our environmental problems and to exchange
ideas across disciplinary areas. I doubt that our current generation
of graduate students is upset by the absence of universal laws
in ecology, and I am one of those people who thinks we should
always turn towards our youth for vision (and our elders for moderation).
The type of ecology Jim hopes to resurrect has had its day,
and the time is now ripe for a different type of ecology, a sophisticated,
frustrating, but useful science.
Peter Kareiva is a Professor of Zoology at the University of Washington,
Seattle, WA 98195. The ideas expressed above were developed as
a result of reading Jim Brown's essay while teaching conservation
biology at the Mountain Lake Biological Station in Virginia.
To comment on the ecoessay or this response to it, see our discussion forum.