As part of Charles Darwin’s 200th birthday celebrations, the February 6 edition of Science brings several review papers on diversification and speciation, the processes that ultimately produce biodiversity. This issue also carries several original research articles on these same topics. If you don’t’ have a subscription to Science, I recommend you spend that extra $10 bucks at your closest scientific bookstore – you’ll get your money’s worth. I could only count a handful of astronomy papers in this week’s edition…
 
The introduction by Andrew Sugden and colleagues notes that evolutionary research is growing fast, these last ten years of the journal Science carrying more articles, reviews and commentaries on evolution than any equivalent period in the past. This is a sure indication that the scientific community continues to rock to Mr. Darwin’s tune (see posting “Will Biologists Rule the World?”).
 
The opening editorial, signed by Bob May and Paul Harvey, themselves luminaries from the University of Oxford, spells out the well-worn points about the embarrassing ignorance surrounding our planet’s biological wealth (we have names for only about 15% of the total estimated number of extant species), and the sorry state of biodiversity in general (extinction rates estimated at 100 to 100 times the historical average). Glazing this calamity, May and Harvey bring the figures from the Millennium Ecosystem Assessment (produced with major funding from the GEF) – 15 out of 24 ecosystem services are degraded or being used unsustainably.
 
But no new themes, no new ideas, no new messages. The opening editorial the prestigious Science, commemorating Darwin’s bicentennial, penned by two of the most important modern names in biology, is not bound to reverberate further. Make not mistake: May and Harvey reiterate the colossally important challenges facing our planet and humanity in particular. However, for some reason, these horrific figures haven’t caught up with the general public, with legislators, and with those in charge of making decisions on funding both research and conservation responses to these problems. Is it the content of the message which is inadequate, or is it the packaging that is inefficient? Perhaps most people don’t genuinely care because they can’t picture the impact of these developments on their daily lives – or not just yet. It is like the New Yorker cartoon where, facing a cold gusty wind, a certain fellow remarks to a colleague: “Long term, I’m worried about global warming; Short-term, about freezing my behind”. Speaking about short-term worries, periods of economic depression like ours today can help make 100 times extinction rates look as concrete a problem as the sun eventually burning through its hydrogen fuel.
 
There are very interesting research papers in this issue. I call your attention particularly to Forbes et al. (Sequential sympatric speciation across trophic levels, Science 323:776-779, 2009), and to Carnaval et al. (Stability predicts genetic diversity in the Brazilian Atlantic Forest Hotspot. Science 323:785-789, 2009). The first looks at how shifts in host plants by species of flies may cause adaptive radiation of parasitic wasps associated with them. As the authors state, “A major cause for biodiversity may be biodiversity itself. As new species form, they may create new niches for others to exploit, potentially catalyzing a chain reaction of speciation events across trophic levels.” The corollary of this, of course, is what happens the other way around – meaning how the elimination of species may trigger chain reactions of extinction events.
 
Carnaval et al. revive the notion that climatic conditions in certain places of the tropics during the Pleistocene may have contributed to the persistence of species in “refugia”. Using geographic distribution and genetic data deriving from relatively common tree frogs, and employing paleomodeling tools, they pinpoint three such refugia inside the Brazilian Atlantic Forest biodiversity hotspot, itself one of the highest conservation priorities worldwide. They conclude by recommending immediate attention to the Bahia “refugium” because of the high degree of forest degradation and fragmentation. This area, in fact, has been proposed as a conservation priority corridor (Central Atlantic Forest Corridor) during the mid-1990s, drawing from related studies dating as far back as 1973 (such as those by P. Müller, looking at vertebrates, and by Warren Kinsey, who analyzed the distribution of Atlantic Forest primates). In 2000, Costa et al. (Biogeography of South American Forest Mammals: Endemism and Diversity in the Atlantic Forest, Biotropica 32:872-881, 2000) examined the mammals of the Atlantic Forest, supporting the idea that the distribution of these and other vertebrates groups in that hotspot is structured in the form of centers of endemism. It is a bit disappointing that Carnaval et al. did not make reference to these earlier studies, or to the ongoing work to try to conserve the Central Atlantic Forest Corridor.