Balance

By this time most of you have probably read all about Mark Lynas, the anti-GMO activist who decided that GMOs are actually a net benefit to society.  I’ve been asked by a few people to comment on how I feel about Mr. Lyna’s changing sides.  I think they expect me to be jumping up and down for joy.  But that’s not how I feel at all.  I’m happy when anyone decides to let research lead them to a conclusion rather than politics or gut feelings, but in this case it also makes me nervous.  This is because some people tend to travel too far towards one side or another.  I’m just as fearful of the damage that people who are radically pro-GMO may cause as I am of radically anti-GMO activists.  And, in my opinion, this guy just seems to be radical.  Saying that you have research that supports one side of an argument is fine, but in almost all cases there is research that supports the other side too, and you ignore it at your own peril.  Balance people — Balance.

Where did the 10-20-30 rule come from? Is it adequate?

We’ve been having an interesting discussion over on the Urban Forestry group on LinkedIn on the origins and suitability of the 10-20-30 rule for tree diversity in urban forests.  For those that aren’t familiar, the 10-20-30 rule is a guideline to reduce the risk of catastrophic tree loss due to pests.  The rule suggests an urban tree population should include no more than 10% of any one species, 20% of any one genus, or 30% of any family.

 

The first published reference to the 10-20-30 rule (often referred to as just the 10% rule) was by late Dr. Frank Santamour, Research Geneticist at the US National Arboretum in his paper Trees for urban planting: Diversity, uniformity, and common sense, which was presented at the 1990 Metropolitan Tree Improvement Alliance (METRIA) conference.  While Santamour is commonly credited with the 10% rule he notes in his paper, “I am not sure who first propounded the “10% rule”, nor am I sure that anyone would want to take credit for it, but it is not a bad idea.”

 


The other question on the LinkedIn discussion is whether the 10-20-30 rule is adequate to ensure genetic diversity in urban and community forests.  My personal is opinion is that the rule is inadequate but far preferable than the status quo in most communities.  If we consider the current issue with emerald ash borer (EAB) in North America, following the 10-20-30 rule means we would accept the loss of 1/5th of our urban canopy since both of the commonly planted ash species (Fraxinus pennsylvanica or F. americana) are highly susceptible to EAB.  On the other hand, many community tree populations the US currently include 30% or more maples, so 10-20-30 would actually be an improvement.

 

A limitation to the 10-20-30 guideline that Santamour acknowledges is that the rule does not afford protection against insects with a broad host range such as gypsy moth or Asian long-horned beetle.  However, while these pests can, and have, caused widespread damage they do not appear to threaten nearly total annihilation of an entire species or genus ala specialists such as chestnut blight, Dutch elm disease or EAB.  Moreover, a wide diversity of species is still a better defense even against generalist pests, unless you happen to get lucky and plant a monoculture of the one tree they won’t destroy.

 


One of the inherent challenges in the 10-20-30 rule is implementation.  What is the tree population in question?  Are we talking about a city? A neighborhood? A block? If there are 10 trees on a block do they all need to be different species? Some have proposed corollaries to 10-20-30 such as the “Look around rule” (or “Look around, fool!” if you prefer the Mr. T version).  This guide states if you’re getting ready to plant a tree; look around and if you already see that tree, plant something else.  The problem with diversity on a very small scale is we can end up with the ‘menagerie effect’ – one of these, one of that, one of those – that often lacks aesthetic appeal.   Ultimately this becomes a challenge for urban foresters and designers working together; how do we incorporate diversity guidelines within established design principles.

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News flash – genes don’t explain everything!

Last week dedicated blog follower Ray E. sent me this link to a story in the Smithsonian magazine.  It’s a fascinating look at adaptive responses by frog eggs and apparently is causing quite a stir in the evolutionary biology community.  Phenotypic plasticity, which is the ability of an organism to modify its appearance or behavior based on environmental cues, is being hailed as a “revolutionary concept in biology.”

I don’t get it.

Anyone who’s studied plants for any length of time knows about this phenomenon.  It’s why plants grow taller in the shade than they do in the sun.  It’s why leaves inside a tree’s canopy are larger and thinner than those on the outer layer. In fact, it’s that darn phenotypic plasticity that can make data collection so difficult for those of us who do field research.  Minimal differences in wind, water, soil chemistry, etc. in a research plot (or a garden, for that matter) are magnified once plants start responding to them.

This leads to one of my pet peeves about the state of biological research over the last few decades.  If you look at the research that gets the big grant dollars, it’s either at the smallest scale (like molecular genetics) or the largest (like systems ecology).  Those of us who are fascinated with how organisms work are pretty much left to our own devices to fund research.  (The exceptions to this rules to a certain extent are human and veterinary medicine.)

While this may seem abstract to most of you, the funding imbalance filters down into the teaching function of colleges and universities.  When I was doing my undergraduate and graduate degrees, my university had a bryologist (someone who studies mosses), an algologist (marine and freshwater algae), a botanist who specialized in diatoms, and so on.  Most major universities had a reasonable number of faculty with expertise over distinct groups of organisms.

As these faculty retired, they were replaced by new faculty whose value was measured more by potential grant dollars than by replacing the loss of expertise. Thus, we have fewer entomologists or mycologists or even horticulturists, as universities scramble for the federal dollars (and substantial overhead) needed to support their institutions and obtainable by a small and select group of researchers.  And university curricula reflect this shift, with the disappearance of distinct programs in botany and horticulture and plant pathology and weed science and crop science, as they are mishmashed into bland and unappealing “plant science” departments.  Or worse, simply “biological sciences.”

So it’s no great surprise, I guess, that many evolutionary biologists are amazed at the “revolutionary concept” of phenotypic plasticity.  I’m not sure many students – or their professors – spend as much time looking at and learning from organisms as they used to.

Over-Interpreting

One of the things that scientists need to be able to do is to figure out what the research that they conduct means without over-interpreting it.  This isn’t as easy as it seems, for example, if a particular pesticide at a particular dose kills mice, then should it also kill humans?  Without testing we really don’t know – though we certainly have suspicions.  If we allow our suspicions to take over and we say that, based on the mouse data, the pesticide necessarily does or doesn’t affect humans then we’re over-interpreting.  Most (dare I say all?) scientists have been guilty of over-interpreting their results – or the results of others — at one time or another in their careers.  It’s a hazard that comes with the job.  Unfortunately it’s a hazard that comes with journalists jobs too — often over-interpreting what scientists say.  Recently I had the opportunity to see an online lecture (a TED lecture) on this very topic and thought it was worth sharing.