Deciphering the evolution of birdwing butterflies

[wollastoni]

An interesting article about Ornithoptera evolution, in open access on the web :

Deciphering the evolution of birdwing butterflies 150 years after Alfred Russel Wallace

It may interest some of you

[exoticimports]

Thanks!

A very interesting paper.

Though some elements of dispersal and extinction don't, to my mind, fit the likely reality. For example, immediately following the discussion of OV, the authors state "we underline the important role of extinction in this mechanism because suitable habitats were probably continuously destroyed by successive environmental changes, resulting in the likely extinction of species unable to disperse or adapt."

However, I can see no cause- certainly not higher sea levels or warming- that would have caused the extinction of OV in the Bismarks. If OV did indeed begin in the Bismarks, it should still flourish there.

Chuck

[Adam Cotton]

Chuck,

They are not saying that what we know as Ornithoptera victoriae became extinct in the Bismark Archipelago. What they are saying is that the Aetheoptera common ancestor of O. alexandrae and victoriae probably arose in what we now know as mainland New Guinea and spread through the Bismark Archipelago to the Solomon Islands (note that the whole area may actually have been a single landmass at that time) and the common ancestor subsequently became extinct everywhere except where O. alexandrae and victoriae now live. That common ancestor was neither of these two species (it probably looked a bit like both species in some ways, particularly wing shape, but may have looked quite different in others), and has evolved into them in the relevant habitats where they live, but died out elsewhere.

This has certainly occurred time and time again in very many butterflies, and indeed in very many different animals. For instance not that long ago there were many species of large mammals roaming the UK that just don't exist there any more, because they were unable to adapt to changing local conditions and died out.

Similarly the common ancestor of O. alexandrae and victoriae may not have been able to adapt to changing conditions in the Bismark Archipelago (maybe as the sea level rose, splitting one larger land mass into islands) and became extinct, just as it probably also became extinct in all areas of New Guinea island that it previously inhabited except near Popondetta. One possible hypothetical explanation could be that the available Aristolochia species could have died out in the Bismark Archipelago for some unknown reason, and without foodplant the butterflies were doomed. There are many other possible reasons why the ancestor went extinct, and the chances are high that we can never be certain what caused the extinction.

Adam.

[Adam Cotton]

Looking at Figure 3 in the paper, it seems that the Solomons, Bismark Archipelago and New Guinea may not have been a single landmass, and my suggestions that this could be the case in my reply above would in themselves be erroneous. However that in no way alters the basic argument of my reply.

Adam.