Today is the start of the Second International Maple Society Symposium. UBC Botanical Garden is hosting the event, so it seemed fitting to feature one of the maples from the garden to mark the occasion.
Acer pectinatum subsp. maximowiczii is a snakebark maple found in central China. Depending on the taxonomist, it is one of at least five subspecies of Acer pectinatum. Other taxonomists do not agree that this is a subspecies of Acer pectinatum, and instead suggest that it is its own separate species, Acer maximowiczii.
What is the origin of these disagreements? In the case of these five entities, the origin is “evolution in action”. One difficulty with plant names is that they are subject to the notion that the names must somehow represent evolutionary relationships, and when they don’t, the names must change. This system is a great aid to understanding plants because of its organizational structure. Unfortunately, the system can break down a little bit when attempting to impose it on biological reality.
Unlike a structured hierarchy of names, biological reality is fuzzy. Here’s an analogy that pertains to the situation with Acer pectinatum. Imagine that a species is represented by a piece of soft gum. Pulling the gum apart into two separate pieces represents the formation of a new species from a parent species. But what would happen if it took tens or hundreds or thousands of thousands of years to pull apart that soft gum into the two separate pieces. At what point, as an observer, would you recognize that a new piece is being separated from the parent? At what point do you say that the thin stretch of gum between the two pieces is small enough to be insignificant, and that for all practical purposes, you have two pieces of gum? What happens if somewhere around midway between the gum being pulled apart, you were asked to decide whether you currently have two pieces of gum, or simply one piece of gum that is being pulled apart into two?
That’s the challenge of Acer pectinatum and its subspecies. Some taxonomists say they see two pieces of gum, even if the break is not yet a clean one. Others say they see one piece of gum that is splitting, but it’s still one piece of gum. There’s a good reason why these very-closely-related-for-now-in-evolutionary-time taxa are called “species complexes”!
Nature resource link: Hummingbirds and Torpor (via GrrlScientist – link to Twitter account as blog is now abandoned) shares a fascinating account of the energy conservation adaptations of these crucial pollinators.