Reclassification of our species?

It was my dearest wish that this would be replied to by one (or more!) of our members who have kept their scientific background alive and well. Sadly, mine has slowly atrophied in the 40 something years since it was hammered into me.

Firstly, much as I enjoy blaming the EU for everything (and if I can't blame them I have politicians, the US, do-gooders and religion to fall back on ) I have to agree it is nowt to do with them!

So, who is the guilty party? Simply the answer is taxonomists and geneticists. Are the changes reasonable? in some cases, yes. Are these changes confusing? To us old fogies, indescribably so. Lastly, why the changes?

Well, the classifications of life have always been rather more haphazard than we might like to think. For example, in the early days of the Linnaean nomenclature newts and lizards were all lumped into the single genus "Lacerta". Not unreasonable at the time, as the classification depended largely on gross physical features and, let's face it, there are still millions of people in the UK who can't one from t'other. 

Later, it was recognised that newts were completely distinct from lizards so they moved into Triturus, while Lacerta remained for lizards. By this time, geographical distribution and fine details of bone structure were also being used for such differentiation. Even I, however, can remember when Lacerta included Wall Lizards and Common/Sand Lizards (amongst, obviously, many others). Even on the basis of gross physical characteristics it was obvious to me that the Wall Lizard group were extremely distinct from the "typical" lacerta. So, apart from taxing my memory, the separation out of "Podarcis" was entirely logical. So that (together with many other changes) seemed totally logical.

So, before we move onto the next stage we should perhaps ask ourselves just what the distinction is between different species/genera. And, surprisingly, that is not at all easy. We are all familiar with the traditional definition that animals of the same species can mate and produce fertile offspring and of closely related but differing species produce infertile offspring. The simple examples we are all familiar with are lion x tiger =  infertile tigon, horse x donkey = infertile mule and, of course, green lizard x balkan green lizard = infertile something or the other. So, that definition appears to work fine. Sadly, it falls flat on its face with, for example, the green frog complex. There are, I believe, about 200 other definitions of what constitutes a species. The only thing they all have in common is that they all fall flat on their faces in some respect or another.

The underlying problem is that we are trying to apply a rather arbitrary artificial man made categorisation system to something that did not necessarily evolve on "logical" lines and that is continuing to evolve all around us.

Enter the genetecists. With the use of genetics, at long last we had a system whereby we could establish the exact relationship of one group of animals to another (note: I did NOT say species). Using this it became apparent that genetically, the Common Lizard had a totally unique genetic signature which showed it to have evolved independently from other lacertids to the extent that it could be argued that it should be in a totally separate genus. Thus the resurrection of a formerly proposed genus of Zootoca.

Was this particular change reasonable? In my opinion, yes. Taking the traditional definition regarding cross-breeding between species, generally only species within the same genus will cross breed. So far as I am aware, the Common lizard, despite having the widest range of any land living reptile, thus overlapping with many other lacertid species, is not known to cross with any of them. Additionally it definitely is physiologically a truly unique species. Yet, even this reclassification is disputed by some.

Taking another example you mention, we have the (now) Western Green Lizard (Lacerta bilineata) and Eastern Green Lizard (Lacerta viridis). These two groups have long been separated into two distinct sub-species (Lacerta v. bilineata and L. v. v.) on the basis of geographical distribution and physiological differences (although the latter are marginal and inconsistent.) Recent genetic research established a clear genetic difference between these two groups. Given the time elapsed since these genetic differences arose and the extent of those differences, the researchers chose to split them into the two distinct species.

They backed this up by cross-breeding them and then breeding from the offspring. This nearly met the traditional criteria as although the first generation were fertile this fell off rapidly to nearly zero in succeeding generations. Unfortunately, my own work with these two groups does not support this (it is worth pointing out that this is a common scenario in captive breeding due to inadequate gene pools, husbandry issues and so on). So, I am one of a number of people who do not agree with this particular re-classification. There are, I might add, others!

This brings us back to the original question - WHO? The answer is that taxonomists are responsible for the classification and, thus, scientific nomenclature on animals. Their work is based increasingly on evidence from geneticists who are undoubtedly experts at defining the degree of difference between groups of animals.

BUT, so far as I can tell, even the geneticists do not agree on what degree of difference defines a separate species. Undoubtedly they are providing an enormous and valuable insight into the evolution of groups of animals and their relationship to one another. Representing this in an easily understood graphical form would be an enormous step forward and extremely informative and educational for all who are interested. Instead, they constantly produce classification changes, often ill-founded, seldom understandable or even agreed by everyone. And they generally do this in turgid scientific terminology which renders it useless to almost anyone other than another geneticist - who might well disagree anyway! It is my belief these two factors mean that their otherwise excellent work is simply leading to massive confusion and incomprehension!

There ...... I bet you're really pleased you asked now! 

I will now wait to be shot down in flames by the competent scientists in this forum who will no doubt be pleased to tell me that I am talking out of my bum!

Chris