Have you read Darwin’s “On The Origin of the Species?”

To be honest, nor has The Aurelian. Written in or around 1852, it caused enormous controversy at the time, and its findings are still disputed by both a number of self-delusional idiots and respected bioevolutionists (although to be fair, they dispute different parts).

But the interesting thing is that while Darwin dealt with variation, change and taxa, it’s generally agreed that one thing he failed to successfully address, in spite of the book’s title, was the origin of species. This was possibly deliberate. Whilst it is an almost obvious extrapolation of what he did cover, Darwin was smart enough to leave conclusions to his readers. Why? Because it doesn’t take much to realise the implication – that the human species itself also has “origins”.

Melitaea phoebe (l) and Melitaea ornata (r)

For us lepidopterists, it doesn’t take long for the question of species to arise. We look at two very similar butterflies, say the Knapweed Fritillary, Melitaea phoebe, and the Eastern Knapweed fritillary M. ornata. Quite clearly two different species (the larvae have different coloured heads), yet the adults are remarkably similar. The principal distinguishing feature is the shape and connectedness of the small chevron shaped marginal marks on the hindwing.

Thymelicus sylvestris (l) and Theymelicus lineola (r)

There are many such similar pairs. The Small Skipper, Thymelicus sylvestris and the Essex skipper T. lineola. The former has the underside of the antennae orange, the other black. Not surprisingly, the two species were not identified as separate until the end of the nineteenth century.

Plebeius argyrognomon (l) and Plebeius argus (r)

Two very similar blue species, Reverdin’s Blue, Plebeius argyrognomom and the Silver-Studded Blue, P. argus, distinguished in the field by the amount of orange in the forewing underside margin.

And then other pairs, so similar that they cannot be distinguished without a close examination of genitalia – that’s right, genitalia. Clearly, it would seem that these species must be in some way “related”. That either one evolved from the other, or that at some point in their history, there was a common ancestor.

So how does speciation happen? And are we entirely clear about just what we mean by species anyway? Why can’t we tell from looking at DNA?

So many questions, so few answers. But we’ll hope to explore the issue a little more in future blogs.