Metapopulation Ecology

Ilkka Hanski Oxford University Press: 1999. 313pp £22.50 (pbk)

As we field biologists see our favourite study sites succumb to anthropogenic assaults, we must increasingly spend our time searching for ‘pristine’ habitats in which to study natural ecological phenomena. They are nearly impossible to find, but, if found, are cherished for whatever information can be gleaned before they, too, become victims of the plough or the axe, acid rain or nitrogen run-off. Of necessity, ecologists have either partially or wholly redirected their research towards the effects of these and other anthropogenic disturbances on remaining ‘natural’ systems.

This shift has not come easily to those trained in classical ecology — the purist's sentiment that basic research is superior to these more ‘applied’ questions is alive in all ecological sub-disciplines. Fortunately, many researchers (at all levels) now regard such classical idealism as snobbery at best, and harmfully delusional at worst. Ilkka Hanski shows his colours by stressing practical applications throughout this tour de force exposition of the metapopulation approach to ecology, evolution and conservation biology.

The metapopulation approach recognizes the influence that otherwise discrete populations can have on one another when neighbouring patches exchange small numbers of migrants. This network of populations, when viewed in its own right, may express very different dynamics from those of its separate population components.

The accelerating growth of this field, fuelled in large part by Hanski himself, has ecologists in other areas looking nervously askance. How much bigger can this bouncing baby become? Will it come to define conservation biology? Can the world be finally understood only if we consent to view it through an Esheresque maze of ephemeral patches set within networks of even more patches?

Fear not. Here lies neither a diatribe nor a plea. Hanski meticulously details the history, growth and empirical and theoretical underpinnings of metapopulation biology. He approaches the subject in a down-to-earth manner, concentrating on his prime motivation — to present a variety of concepts and models which may help us to understand and conserve what still remains. Being equally astute in theory and empiricism, he manages this with aplomb.

While admitting that the metapopulation approach will not apply in every instance, Hanski attacks its sceptics in a lively manner: “I want to make the point that ignoring the actual spatial population structure of any species, at whatever the scale that structure might occur, would be an exceedingly silly thing to do.” Bravo! Leave the philosophically inclined to debate the delineation of a population, and let's get on with the business at hand.

And serious business it is — this book is not for the faint-hearted. The density of information, page after page, is rather like a Yorkshireman's description of a good cup of tea — thick enough to stand a spoon in. Hanski's attempt at making his work accessible to the bulk of population biologists is generally successful, and impressively eloquent in arguments he considers crucial. However, he also assumes a high degree of knowledge, as well as motivation to understand the subject. I would suggest new graduate students have a basic ecology text or dictionary handy to follow the arguments fully. The casual reader can still come away somewhat enlightened, as plainly written summaries begin and end each chapter, and often each section. Frankly, I found his treatment a refreshing refusal to cater to the lowest common denominator.

Unfortunately, Hanski's impressive style is ill-supported by abysmal print quality. The blurred outlines of the letters complemented the small, overly-serifed font to give me a solid headache within 20 minutes of reading. I thought I needed glasses, when in fact I needed a different production editor.

I applaud Hanski for embracing what many ecologists emotionally reject: the incorporation of evolution into what has largely been an ecological domain. Indeed, the few empirical genetic studies that do exist bolster his assertion that “local adaptation influences spatial dynamics and spatial dynamics influence local dynamics”. However, evolutionists must be prepared for an unconventional use of “fitness” to refer to population growth rate (as well as to individual fitness) — a usage justified by model results which show that population growth rate can be important to evolution at the metapopulation scale.

I learned a lot in areas I knew dimly and was entertained in areas I knew well — a sure sign of a good book. Hanski's emphasis on the application of models, particularly to conservation biology, will make this work not only a classic for academic population biologists, but an essential reference for managers and conservation planners as well.