Author: Luis (Page 4 of 66)

It is easy to get obsessed with heritabilities when you start working in breeding and genetics. The idea that a fraction of that variability we are observing can be explained by pedigree (or family structure or clonal differences or whatever) is appealing. It gives us an idea of control: there is a whiff of causality in our work. If the trait I care about is heritable THEN I can successfully breed for it.

However, we need to remember that it is a fraction of the variability we care about. If there is little variability, there is little room to select farther to the right of the distribution for the trait.

A typical example in trees would be stem diameter vs basic wood density. The heritability for density is, on average, around 0.6, while for diameter is 0.2 in a lucky day. However, the within-site coefficient of variation for density is about 8% but over 20% for diameter. Much more room to move in diameter.

Nothing groundbreaking, particularly if you have been working for a while. Just a handy reminder if you’re a newbie in breeding things.

Gratuitous earworm: In my head, “more than heritability” sounds like the famous More than a feeling.

I cringe every time I hear the term “future proofing”. It can be read as doing something to avoid facing the future or as doing something that will survive whatever the future brings. The first meaning is non-sensical, while the second is a fool’s errand.

When working in breeding (plants, animals, trees) it is unfeasible to cover all possible environmental and market futures. What we can do, however, is to embed variability and flexibility in the breeding programme, so we can better pivot under changing conditions. There is no guarantee that the crop will always survive the new conditions.

Why was I thinking about this? I’ve been contrasting the forestry plantations stories of Australia, Chile and New Zealand and in the previous post I pointed out the changing participation of Eucalyptus species in Australia and Chile.

In the Chilean case, the idea was to use Eucalyptus globulus—a high-growth & high-quality fibre species—for the short-fibre pulp industry. The expanding estate needed another species that, although with lower pulping quality, would cope with colder environments: E. nitens. After a few years there were some efforts to create the E nitens (mother) x E globulus (father) hybrid, with the aim of getting pulping quality closer to E globulus but with cold tolerance closer to E nitens.

For a few years the E globulus estate expanded substantially, until… a climate change-induced mega drought dramatically reduced forest productivity AND defoliation by Gonipterus platensis (with 4 generations per year) took its toll. Companies are now planting either E nitens or the E nitens x E globulus hybrid (some people call it gloni, for GLObulusNItens), which far outperform E globulus under the current abiotic+biotic environmental conditions.

The predicted “future” for 20 years ago was dramatically different from reality. There was no future-proofing in any meaningful sense, but there was variability and flexibility and good work to cope with a changing environment.

The last 2 months or so I have been revisiting the Chilean forest sector and mentally comparing values with other two places: Australia (where I worked 6 years) and New Zealand (where I’ve been living for close to two decades). Previous related posts here and here.

We often get stuck considering specific values of dynamic systems instead of the overall trends; a bit like worrying about a specific frame instead of the whole movie.

New Zealand radiata pine has been remarkable stable: around 89% of the planted forest estate area for a long time and with a fairly low percentage of eucalypts (under 2%). In contrast, Australia and Chile have experienced large changes on the percentage of eucalypts (mostly Eucalyptus globulus and E. nitens) versus radiata pine during the last 20 years. In Chile this change has been accompanied by capital investment in processing facilities.

At the same time, the Chilean curves hide a fundamental change during the last 10 years.