Grey-faced/great-winged petrel

[Neil Fitzgerald]

What was the justification for grey-faced petrel being a subpecies of great-winged (Pterodroma macroptera) in the latest Checklist of the Birds of New Zealand? Obviously didn't agree with Onley & Scofield (2007) who elevated it to species (P. gouldi), but I'm not sure exactly why.

[Ian Southey]

Neil

I suspect even the authors would regard the checklist as a pretty conservative document and I think this is appropriate given the nature of the publication.

Regarding species and subspecies as taxonomic ranks I don't see the need for the intense interest that it seems to generate among birders. It's a theoretical construct and just how you allocate your birds to it depends on what species concept you are willing to accept and what you intend it to mean. Actually only one set of species concepts (Biological Species Concept) develops an understanding of why subspecies should be recognised while its major competitor (Phylogenetic Species Concept) explicitly says they are a completely useless category. The checklist seems to have a bob each way here.

However you name your terminal taxa what is important is only whether or not they are natural groups and to a lesser degree how well they can be identified. It's a simple solution - just pay attention to everything.

Ian

[Neil Fitzgerald]

All true. Perhaps we need a new concept, the Political Species Concept. It is a bit unfortunate, but a lot of things these days require clear boundaries and definitions. It's just those stupid organisms that wont sort themselves into nice discrete units that causes so much bother.

[Graham Saunders]

True Neil. Linnaeus worked hard to devise this lovely taxonomic system and the ***** creatures and flowers can't be bothered to follow it. Of course, the phylogenetic and biological species concepts are no good; the genetic species concept will inevitably win. In a decade or so we'll be doing birdwatching with PCR kits, and rather than setting mystery bird quizzes with old technology (photographs and mp3s) you'll be giving us a sequence of As, Cs, Ts and Gs (and maybe Us to throw the unwary).

It's always amsued me that in the past 150 years or so that Physics and Chemistry have undergone huge advances, and yet poor old biology iseems to be still pretty much stuck in the 19th century with Linnaeus, Darwin and Mendel.... and arguing over whether Grey-faced and Great-winged Petrels should be split. That's a bit like arguing over how many angels fit on the head of a pin, isn't it?

[Neil Fitzgerald]

My interest in these things is in trying to understand the differences between different groups of organisms, the weight different authors place on them and why.

[Ian Southey]

Neil

You probably need a crash course on "THE SPECIES PROBLEM". Good luck.

For short answers Ernst Mayr is in print saying that the species and subspecies categories are intended not to assign different values to the groups of organisms so designated but to communicate information about them. They are, however, not usually understood in this way.

Most modern species concepts begin with recognising species as natural populations that effectively interbreed (over a bit of space and time perhaps) and that there is variability within them. Based on this species differences are qualitative and some species are hard for us to pick, but presumably not themselves. Subspecies are intended to reflect that they do or might interbreed to some (usually minor) way and that they do not overlap in their ranges. Some authors would suggest either that any actual or potential interbreeding between between such groups has no significant impact in which case they are actually species or that it does have a significant impact and they are simply not worth recognising as taxonomically different. Beyond this it just starts getting way too hard to follow.

Interestingly taxonomic practice is often a bit different. It prefers that every individual of a species is distinguishable from every member of every other species. This is usually true but there is nothing in theory to justify this and there may be another layer of actively forming species that we are just not recognising.

Thinking has actually moved on considerably over the years and the recent field research on "ecological speciation" involving Galapagos finches, crossbills and sticklebacks interests me greatly and seems to be leading to a useful reorganising of old ideas. Taxonomy is clearly in a state of flux but it will require some time to get enough work done to tidy it up. In the end I think ecology and behaviour are still the key factors and you can bear this in mind when you are watching your birds. The PCR kits will be handy for the simpler cases if you happen to have one.

Ian

[Graham Saunders]

Thinking has actually moved on considerably over the years and the recent field research on "ecological speciation" involving Galapagos finches, crossbills and sticklebacks interests me greatly and seems to be leading to a useful reorganising of old ideas. Taxonomy is clearly in a state of flux but it will require some time to get enough work done to tidy it up. In the end I think ecology and behaviour are still the key factors and you can bear this in mind when you are watching your birds. The PCR kits will be handy for the simpler cases if you happen to have one.

Ian, you seem to suggest that with some tinkering here and there the system will work... Is it not a case that the system is plain wrong? It's an approximation, a man-made model, it ain't the truth. It's like Newton's mechanics to Einstein's relativity; it's the Bohr atom to the wave equation, and Fermi-Dirac and Bose-Einstein statistics. Like those models it's fundamentally wrong, but it gives acceptable answers on occassion. What is needed is not some new thinking on 19th century ideas, but a revolution, a paradigm shift. Someone clever needs to cast aside Linnaeus and Darwin and Mendel, and to approach nature with a fresh mind. Rather than trying to get the data to fit the hypothesis, develop a new hypothesis that better fits the data. It's happened in chemistry and physics, why should it not happen in biology... Afterall the species problem has been around since before Darwin; 200 years and still no one has solved it!

[Ian Southey]

Graeme

I disagree. I think its close to becoming something useful. There are limited number of factors involved so it's more a matter of balance and perspective. And also some of the fanatastic fieldwork and experiments that people have been doing. There has been a person or two involved over the last century or so and some excellent work on natural selection in the wild in particular done lately. There are some ideas however, both old and new, that die hard and this makes it harder to follow.

Ian

[Graham Saunders]

How long can one flog a dead horse before it's obvious to all that the poor nag's had it?

$100 says that you won't be able to give me a satisfactorily all-encompassing scientific definition of 'species' before you or I pop our clogs. And I'm so confident of this I'll give you odds of 100-1 - let's see your dollar!

And I would go on to add another $100 says that there will be a revolution in 'taxonomic' biology with a system based on the molecular victorious, but that may occur after our lifetimes...

[Ian Southey]

Graeme

You're welcome to my dollar and I'll be happy to send it as soon as you do pop your clogs. No hurry though.

The problem is that the argument is so complex now that I think it will be determined more by surviving users than a sudden revolution. Legal and popular considerations cloud it still more. One thing I am sure about is that it will not be led by any molecular approaches now being used. They are essentially morphological characters and subject to the same problems as they are. Their value lies in the fact that there are an awful lot of base pairs to be compared and that it hasn't been done before. If you look at these often you will have seen how unstable some of their placings are for some groups.

Forensics seems to show that DNA techniques can carry out identifications almost to the level of individual people but they are long way from identifying groupings like species. I think that if you are looking for a real classifaction of actual biological entities you have to look at them in their world as they live and breathe - whole birds, whole populations of birds etc. You might not appreciate the classics but I'd leap even further back to Aristotle and suggest it is still about trying to carve nature at the joints. Over the years we've done some good things and some bad things toward this and we're just a bit stuck right now but I thinkj we'll get over that.

Ian