Convergent Evolution

Moth trapping has been fairly successful this autumn, though the dearth of migrants has put a dampener on things. For some reason, after several years of trapping, I still expect to be buried by a swarm of Death's Head Hawk Moths whenever I hear the hum of the MV bulb on warm October evenings.

As it is, on the migrant front, I've had to make do with a Vestal and a couple of Small Mottled Willows (not to be sniffed at, but equally well, not Palpita vitrealis), and so, with nothing more exciting to entertain me, my mind began to wander...

To what precisely? A really nice natural phenomenon called 'Convergent Evolution', it's fairly common in the animal kingdom (and no doubt elsewhere), and is basically when distantly related creatures, capitalising on similar ecological niches, evolve similar adaptations independently. Good examples are the way flight has popped up in insects, birds and bats - distantly related creatures, all with the same useful adaptation.

In a broad Darwinian sense, there is only one problem that each species must adapt to, that is, the problem of surviving long enough to pass on ones genes. Many Scientists argue, that since any life that evolves anywhere will always face this one problem, and natural selection will always produce optimal solutions to a problem, the evolution of intelligence (supposedly the optimal solution, as opposed to being able to reproduce every 20 minutes like Bacteria), as seen in humans, and various
other animals, is inevitable.

Merveille du Jour

Acleris literana
 

This is a bit of an over simplification of the argument, but gets the general gist of it. But what does this have to do with moths?
 The fairly distantly-related Acleris literana (a micro moth which flies from August to May), and the famous Merveille du Jour (marvel of the day in French) both of which I caught in the garden during October, exhibit a magnificent green marbled colouring that allows them to blend almost seamlessly into any lichen-covered substrate - a cracking example of convergent evolution!

Presumably, since both feed on Oak, and therefore inhabit nice Oak Woodlands with lots of Lichens, being able to hide on the abundant lichens whilst resting during the day proved an excellent way to avoid predators and survive to reproduce, and so was selected for and evolved in both species.

 

Fascinating!