The old frontiers of biogeography

Ecology is often criticized for being a weak science, with limited data, few ideas, and little predictive power. As a practicing scientist, I often feel frustrated by our collective inability to make the same dramatic progress as seen in other fields – for example, physics in the earth 20th century, during the quantum mechanical revolution. But a few weeks ago, I held in my hands a manifest declaration of scientific progress.

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The object in question was an atlas of the global distribution of plants, published in the early 1800s in Copenhagen. (Plantegeographisk Atlas, af E.F. Schouw)

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At that time, systematic exploration of the world’s natural history had just begun to occur. Both North and South America remained largely unexplored by Western scientists, to say nothing of Africa or most of the closed East. Alexander von Humboldt had only returned from his pioneering explorations in the Andes a decade earlier. Until this time, the broad-scale distribution of species had been an uninteresting or unexplored topic. Either no one knew enough about where species were to think the patterns were worthy of explanation, or no one thought the question was relevant, since the Biblical flood narrative provided a simple explanation for the radiation of species from a single point. But evidence began accumulating that not everything lived everywhere, and that some groups of species had complex ranges spanning continents. Coupled with the discovery of fossilized organisms on mountaintops or in inhospitable areas, science was forced to confront the idea that the distribution of life did not have a simple explanation.

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This atlas was one of the world’s very first attempts to synthesize knowledge on plants. It is a beautiful work, printed from engravings onto thick paper, with hand-painted maps for each group of species. But its beauty belies its limitations. You can see that the geography of South America is very fuzzy, with mountain ranges drawn in that don’t exist, and with ambiguous cartography of many rivers systems and coastal borders.

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Empirical knowledge of plants was simply quite weak at this time. You can see on this global map, most of the Pacific islands are represented simply as being the ‘land of the breadfruit’ – hardly a comprehensive description. This atlas represents something of the birth of ecology and biogeography.

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Since then, thousands more botanists have traveled the world, made collections, established taxonomies, and so synthesized knowledge. We are much better informed about the world than we ever have been, and so we are now able to begin to explain global patterns of biodiversity. We now know roughly how many species there are on Earth, and roughly where they live. We have assembled large databases to standardize and share this information. Every day, more scientists are exploring the wild and not-so-wild corners of the planet, and we are progressively getting closer to the truth.

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Holding this atlas made me feel proud of the progress we have collectively made. The road forward is long and difficult, but we are certainly further down it than we have ever been before.

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