A new way to identify individual-versus-community tradeoffs in plants

A major theme in my book, Darwinian Agriculture, which built on old work by Donald (1968) and Jennings & de Jesus (1968), further developed by Anten & Vermeulen (2016) and Weiner (2019) and others, is that tradeoffs between individual-plant competitiveness and plant-community efficiency are key to past and future improvements in crop yield and agricultural sustainability. But identifying those tradeoffs isn’t necessarily easy.

One approach is to use our understanding of plant interactions to predict tradeoffs, as the authors cited above have all done. Sufficiently detailed crop models might help. A second approach is simply to grow different crop genotypes in plots large enough to minimize edge effects — probably bigger than most plant-breeding plots — and compare their yield or other measures of performance, such as resource-use efficiency or yield stability under varying conditions.

Samuel Wuest et al. (2022) have developed an exciting new approach, with two potential advantages over these established methods. Like field tests with large plots, the method may uncover tradeoffs that mere humans wouldn’t imagine, or disprove tradeoffs that we incorrectly imagine! And, rather than using large and expensive field plots, it can apparently detect negative effects of competition on community productivity using pairs of plants in pots!

This figure, from their paper linked above, shows the approach. A genotype’s individual performance in mixtures (horizontal axis), which depends on its intrinsic efficiency, disease resistance, and other traits that benefit both individual and community, but also depends on its competitiveness (benefiting the individual, perhaps at the expense of the community), is generally correlated with the genotype’s “group” (two-plant!) performance, the vertical axis, which would depend mainly on intrinsic efficiency, disease resistance, etc. They call these win-win traits, “vigor.”

Genotypes that fall above the main trend line are putative “cooperators”, which put more resources into community productivity rather than fighting each other. They may have “Biden’s infrastructure alleles”, to coin a phrase. Or “Eisenhower alleles”, if you prefer his 90% marginal tax rate on millionaires and skepticism about the “military-industrial complex.”

Wuest et al. even identified a particular allele associated with the more-cooperative genotypes. This allele apparently reduces wasteful over-investment in roots — wasteful from the standpoint of the community, but sometimes benefiting individual plants at the expense of their neighbors — a “Putin allele”, if you think Putin, himself, is somehow benefiting from the invasion of Ukraine, even if Russia isn’t.

But if that space-invading trait benefits individuals, why has the more-cooperative trait also persisted? Apparently it’s associated with disease resistance which, under some conditions, is more useful than stealing soil resources from neighboring plants.

I look forward to more exciting results from this group.

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