That's the title of a review article just published online by Science. Past and ongoing evolution have important implications for health, agriculture, and conservation of biodiversity, but communication among scientists applying evolutionary biology to different practical problems has been limited. That started to change in 2010, when a bunch of us (including most authors of today's paper) met on Heron Island, Australia, at the Applied Evolution Summit. Scott Carroll (UC Davis and Institute for Contemporary Evolution) had a lead role in both the meeting and the review article.

Evolutionary changes occur over generations, so crop pests and disease-causing pathogens with short generation times can evolve quickly, undermining our control measures. Species with longer generation times, including humans and some endangered species, evolve too slowly to keep pace with changes in their environments. For example, food preferences that evolved when meat and sugar were scarce may lead to unhealthy diet choices today.

Our paper discusses various ways to slow harmful evolution. Refuges not exposed to selection (e.g., by insecticides or fishing with nets) may slow evolution of insecticide-resistant pests or evolution of smaller fish. This approach partly depends on insect pests or fish from the refuges mating with individuals from outside. Refuges might be less effective for populations that reproduce asexually, such as bacteria or cancer cells.

To protect valued species that are evolving too slowly, we may be able to modify the environment to better match their inherited traits. Taxing unhealthy food might help, assuming we're sure which foods are unhealthy. For wild species, moving them to environments to which they're better adapted may work. Obsession with native species may blind us to the fact that their native range is now warmer than it was when they evolved. Unless we can reverse climate change, saving those species may require moving them (or allowing them to migrate) further from the equator or to a higher elevation.

Despite the authors' shared interests in evolution and in practical problems, applying insights from one field to another can be difficult. But I hope that this review will be helpful, both to practitioners and to students of evolution that have not yet narrowed their career options.

Dr. Jahi Chappell has some interesting comments on "learning from nature", and I respond.

Both talks are part of symposia with other interesting speakers.

August 18: Student Organic Seed Symposium, NY Finger Lakes Region

October 28: minisymposium (with Emma Marris, author of "Rambunctious Garden: Saving Nature in a Post-Wild World") on "Saving Nature and Improving Agriculture: Where does Nature's Wisdom Lie?" Washington State University, Pullman

Improving on nature?


I have two invited reviews due this summer, building on the theme from my book, that past natural selection improved trees (and the wild ancestors of our crops) much more than it has improved the overall organization of forests (and other natural ecosystems):

In Global Food Security, Andy McGuire and I will ask, "What can agriculture learn from nature?" If natural selection or some other process had consistently improved the overall organization of natural ecosystems, then agriculture might benefit from copying that organization. If every natural ecosystem had some process that adjusted the relative abundance of species to maximize ecosystem-level productivity and/or stability, then we could (for example) try to match the ratio of grasses and legumes in our pastures to those in nearby grazed meadows. I expect to argue, however, that nothing has consistently improved natural-ecosystem organization, so mindless mimicry of natural ecosystems is unlikely to improve agriculture. The wild ancestors of key crops grew naturally as monocultures, but that doesn't necessarily mean polyculture wouldn't be better. It's still worth studying how natural-ecosystem organization affects productivity and stability, and thinking about which features of natural ecosystems might be worth copying.

In "Evolutionary tradeoffs as crop-improvement opportunities", intended for Field Crops Research , I will argue that past natural selection has been improving individually-beneficial plant traits like drought tolerance for millions of years, leaving few simple, tradeoff-free options for further improvement. Accepting tradeoffs rejected by past natural selection has been key to past crop improvement and that is probably still true.

For a preview, see my discussions with farmer/blogger Chris Smaje and soybean-breeder Clem Weidenbenner in the comments for this post on Small Farm Future.

Chris argues that rotating annual crops with pasture is copying nature. I don't see any close analogs to such rotations in nature, so disagree. The pasture phase might benefit from copying some aspects of natural grazing systems, though.

Clem has various examples of plant breeding improving crops in ways that natural selection hasn't. I agree, but would any of those changes have improved individual-plant fitness in nature? If not, what are the prospects for improving traits like stress tolerance, which would (if tradeoff-free) have improved individual fitness?

Increasing or decreasing oil content beyond its natural range would presumably decrease fitness, even though it may be useful to us. Clem mentions range expansion of crops, which could show that humans can improve traits like cold tolerance in ways that past natural selection on the crop's wild ancestors didn't. I need to read more about this, but I find it interesting that high-altitude maize picked up cold-tolerance genes from teosinte, not the other way around.

UPDATE: a Faculty of 1000 selection.

That's the title of a paper Toby Kiers and I just published in Philosophical Transactions of the Royal Society. We argue that:

"[despite] past selection for inclusive fitness (benefits to others, weighted by their relatedness)... [and despite some] evidence for kin recognition in plants and microbes... there is still ample opportunity for human-imposed selection to improve cooperation among crop plants and their symbionts"

Wednesday I'm off to the University of Illinois, where Michelle Wander and the Agroecology and Sustainable Agriculture program are using my book in a grad course on the Future of Agriculture.

Journal of Bioeconomics


My paper titled Increasing cooperation among plants, symbionts, and farmers is key to past and future progress in agriculture is now available on-line at the Journal of Bioeconomics, if your library has the right kind of subscription. Otherwise, they want $40 to download the paper. It would be cheaper to buy a hardbound copy of my book. The paper has some new material that's not in the book, of course, but the book is still probably a better deal. Does anyone pay that much to download one paper?

I'm in Saskatoon to give a department seminar and speak at a student-organized symposium. I'll add a web link if I find one, but here's last year's, where Wes Jackson spoke. That could have been an interesting debate.

Andy McGuire and Chris Smaje have debated various points here and elsewhere, but they have this in common: they both think about agriculture in creative ways, rather than just parroting organic vs. conventional "party lines." I also really like the Agricultural Biodiversity Weblog.

Andy McGuire, who earned an MS with me some years ago, doing research on cover crops, has just posted a provacative essay titled "Don't Mimic Nature on the Farm, Improve It." He contrasts a well-known agroecologist saying agriculture should "mimic nature" with statements from natural-ecosystem ecologists (and my book) denying the perfection of natural ecosystems and the "balance of nature" hypothesis. He concludes that:

"We can, with ingenuity, wisdom, and a good dose of humility, purposefully assemble systems that outperform natural ecosystems in providing both products and ecosystem services."

I agree, but with some reservations. If the overall organization of natural ecosystems isn't necessarily perfect -- see this discussion -- then it should be possible for us to improve on it, at least by agricultural criteria.

Let's consider a specific example: a pasture grazed by dairy cattle. We want to maximize milk production, subject to various constraints that include long-term sustainability and minimizing pollution. Our reference natural ecosystem is the prairie, grazed by bison, that once occupied the same land. The natural sex ratio of bison is 50:50, like other mammals, but we can get more milk from the same land with a female-biased sex ratio. Similarly, the ratio of nitrogen-fixing legumes to grasses in a natural prairie depends on their relative survival and reproduction, not on how much nitrogen the ecosystem needs for maximum productivitiy. Given the economic and environmental costs of nitrogen fertilizer, we might want to increase the abundance of legumes in our pasture, relative to the natural prairie.

But how? What combination of McGuire's "ingenuity, wisdom, and... humility" will lead to increased legume abundance with the fewest negative side effects? And are we even sure increasing legume abundance is a good idea?

Planting additional legume seed each year might cause enough soil disturbance to increase erosion. Low doses of a grass-specific herbicide would increase costs and perhaps pollution. Ingenuity might suggest introducing a mild pathogen that would slow grass growth without killing it. Humility, though, would identify some of the risks with that approach (for example, the pathogen might evolve greater virulence) and the possiblity of additional, unrecognized risks.

I would suggest trying several approaches in limited experiments (not including the pathogen option!), then doing longer-term and larger-scale tests of those that seem more promising. These tests may find problems that weren't apparent in short-term, small-scale experiments. (Similarly, we need more long-term monitoring of transgenic crops once they're in widespread commercial use. For example, an herbicide-resistant weed mutant is much more likely to arise on millions of acres than on one acre.)

But natural-ecosystem ecologists could play an important role also. For example, it might help us to know what combination of factors limits legume abundance in the natural prairie. If the preferences of grazing animals are key, can we enhance legume survival through grazing management? I don't mean to suggest that agronomists would never think of this without information from natural ecosystems, but comparisons among systems can often reveal patterns that aren't obvious in a single system.

Also, legumes and grasses have different soil-resource requirements. In particular, phosphorus fertilization can favor legumes more than grasses, although the long-term availability of phosphorus fertilizers is a concern. Differences in resource requirements among species have sometimes been proposed to explain the high species diversity of some natural ecosystems. On the other hand, a recent paper in Nature showed that differences in resource requirements among tropical tree species aren't enough to prevent loss of diversity during the seedling stage, when fungicide sprays reduce the diversity-enhancing effects of more-abundant species suffering more losses to pathogens.

Another seminar using my book

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This one is at the University of Illinois, "facilitated by Dr. Michelle Wander, and ASAP Scholars Rafter Ferguson and Ron Revord" and titled Agriculture Evolving: Evolutionary Dynamics from Crops to Ecosystems. I will be meeting with the class in April.

That's the topic of a thoughtful essay by Nathanael Johnson on the Grist website. He gives a reasonable summary of my argument that many hoped-for improvements either involve tradeoffs (some of them acceptable) or radical enough changes that their effects will be hard to predict.

He also cites my colleague Jonathan Foley's suggestion that "we" should "Reduce food waste, eat less meat, and make fertilizer and irrigation available to the farmers that need it."

OK, but who's "we"? Any "solution" that requires billions of people to change what they're doing -- because they read Foley's article in Science? -- will be a long time coming. For example, a few million rich consumers eating less meat -- this would lower the demand for meat so that meat prices decrease so that slightly-less-rich consumers eat more meat, but let's pretend total meat consumption goes down a few percent -- would not have much effect on global greenhouse gas production or food security for the billion or two in greatest need. Similarly, if a couple billion consumers wasted less food, that would free up some resources. But if you and a few friends reduce your waste, it's a drop in the ocean.

Reducing pre-consumer food waste has more potential. Because reducing pre-consumer waste could mean larger profits for farmers, food companies, etc., near-universal adoption of practical waste-reducing methods is at least conceivable. Motivation linked to higher profits also means, however, that the obvious improvements have already been made. Less-obvious improvements are already a major research focus, but more likely to be invented by engineers than ecologists.

Expanding access to irrigation might greatly increase food security, but it would be a big project, perhaps costing a significant fraction of what we spend on war or video games. So I'm not holding my breath.

Increasing access to fertilizer can start small and scale up -- avoiding over-fertilization -- so that's an area where contributions from a few million people (or a handful of rich people) could really make a difference. But I worry about solutions that require on-going subsidies.

And then there's plant breeding. Develop a cultivar that out-performs what's available now, and watch it spread.

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Recent Comments

  • R. Ford Denison: Thanks! I'm sure I often fail to cite papers I read more
  • Clem: Ford: Wondering if you've seen Henry & Nevo Pl Biotech read more
  • Chris Smaje: Thanks for that clarification - makes sense to me. I'll read more
  • R. Ford Denison: I was using "random" loosely, analogous to mutations being random. read more
  • Chris Smaje: Ford, I’m not wholly convinced that forest fires or wetland read more
  • Clem: Yeah, a 50% increase... I'm not that optimistic either. read more
  • R. Ford Denison: I agree that human plant breeders have tools nature doesn't. read more
  • Clem: Ford said: Plant breeders who focus on traits we value, read more
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