One day you are all happy and relaxed, with plenty of time for cooking dinner of any kind. Three course dinner? No problem! Then, one day, just around the corner comes the start of semester. It is a bit like when one is distracted at the beach, waving hello to a friend or loved one and a sneaky wave tackles us and runs us over without any consideration.

On the plus side, I am usually looking for links that could be interesting to first year forestry students. Some times they are about forestry related news, but others are nice implementations of data visualizations that tell an interesting story. That’s when I came across this interesting clustering of New York City neighbourhoods grouped by similarity of proportions of street-tree species, done by Kieran Healy.

Of course one thing leads to the next until I got to this great New York City Tree Map in which one can get information for nearly 3/4 of a million individual trees. Enough to motivate some students. Zoom in until finding a tree you like.

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.