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Araucariaceae Ancestors
By now most people have heard of the ivory-billed woodpecker. News of its presumed extinction and seemingly miraculous rediscovery spread quickly after it was reported just over two weeks ago. Of course, the ivory-billed woodpecker is by no means the first species to be called extinct only to resurface years or decades later; in fact, only a week after the rediscovery of the ivory-billed woodpecker, three “extinct” species of snail were discovered in Alabama. The snails in question – the Cahaba pebblesnail (Clappia cahabaensis), the Cobble elimia (Elimia vanuxemiana), and the Nodulose Coosa river snail (Elimia lachryma) – didn’t get as much press though, because they aren’t what biologists call “charismatic megafauna,” a term used to describe large, attractive, and popular animals.
My favorite story of un-extinction is also not about charismatic megafauna. In fact, it’s not about fauna at all. It’s about flora.
The Araucariaceae family of conifers is thought to has existed for as long as 250 million years. The Wollemi pine (Wollemia nobilis) is a member of the Araucariaceae family, and appears in the fossil record from as early as 150 million years ago until about 2 million years ago. Unsurprisingly, it was thought to be extinct until 1994, when a field officer of the Australian National Parks and Wildlife Service with some botanical knowledge stumbled across a valley of conifers with which he wasn’t familiar. He brought back samples from the unusual trees, which revealed them to be a hitherto undescribed genus and species of the Araucariaceae family.
One of the most interesting things about the discovery is that the remaining trees are genetically identical. This suggests that at some point in its evolutionary history the Wollemi pine passed through a genetic bottleneck – a population drop that reduces genetic variability – in which its population may have plummeted to as few as two trees.
There are perhaps 100 Wollemi pines (which, incidentally, are not technically pines) remaining in the wild, but they have been in cultivation at Kew’s Royal Botanic Gardens since shortly after their rediscovery in 1994. Next year Kew will begin selling trees cultivated from the remaining Wollemi pines to “help directly fund its conservation.”
I have some misgivings about the commercialization of the species. Obviously there’s a lot that we don’t yet know about the growth habit of a plant that we’ve only been able to observe for a decade. The Wollemi pine has been extensively studied, but no one seems to have closely examined any of the factors that might make it invasive. If anything, the fact that the tree has managed to survive through almost 200 million years of changing climate and recover naturally from a population bottleneck of as slim as two individuals suggests the type of hardiness and adaptability that makes a good invader. We know that Wollemi pine survived in part because seedlings are extremely shade tolerant – yet another indicator of invasiveness. Wollemi pine seedlings are able to survive in temperatures as low as -5°C. Perhaps the only thing we know about the tree that doesn’t suggest invasiveness is the fact that it isn’t especially fast-growing.
Am I seriously proposing that one of the rarest plants in the world might become an invasive species? Stranger things have happened. After all, invasiveness isn’t about numbers. But despite having several traits that might indicate invasiveness, large plants like trees (especially slow-growing trees) aren’t especially likely to become invasive.
Regardless of my inhibitions, I have no doubt that the Wollemi pine will be a commercial success. After all, if there is such a thing as charismatic megaflora, then the Wollemi pine certainly is such a species.
