Taxonomy. Straight questions to a complex issue.

[bandeeorchids]

Taxonomy. Straight questions to a complex issue.

In one of the previous Threads a lot of members were questioning and also trying to explain the latest genus name changes from Laelia to Sophronitis and lately to Cattleya.

I am seriously struggling to understand the splitting within the orchid family within the genuses and species.

In the animal kingdom a different species is an animal which is not able to reproduce with an other species from the same genus or in some cases they can but have sterile offspring.

Why in the Orchidaceae family is this not the case? We have hundreds of intergeneric hybrids which are obviously not sterile.

Shouldn't be whatever can produce offspring be the same species or at least the same genus?

Does taxonomy has created the same mess within the trees family or within the grass family?

[lambelkip]

a species is something which forms distinct populations with different genetic characteristics. just because something can interbreed does not mean that it ever will in nature. even if they do cross in nature, they form their own distinct populations away from the place where they cross. in many cases, these hybrids are sterile, do not have an even number of chromosomes, or have different sized chromosomes in each pair.
also, the fact that certain plants can interbreed with a common relative does not mean they can interbreed with each other. for example, Grammatophyllum and Ansellia species have both been crossed with Eulophia, but there have been no successful crosses of Grammatophyllum with Ansellia. it would make no sense to include the three in the same species. exactly how they should be categorized is a matter of ongoing debate, and the recent re-classification is mostly due to recent studies of genetics. in some cases, this research shows that certain groups of species are more closely related than previously thought, and should be placed in the same genus or subfamily. this has led to attempts at creating new types of hybrids, which were at one time believed to be impossible. in other cases, the research has shown that species are not as closely related, and explains why certain types of hybrids are impossible. this same type of research is leading to re-organization of all plant families.

[Hedge]

The ultimate splitters plant group must be Cacti and Succulents - the varietal variants were all accorded different species status and often different Genera too, but DNA research is undoing a lot of this, reuniting siblings as you might say! Given that some variants are due merely to growing conditions and particularly mineral contents of some soils in the case of South African small succulents, this is no bad thing, although it does make it difficult to make sure that your labels are correct.

[bandeeorchids]

Originally Posted by lambelkip

a species is something which forms distinct populations with different genetic characteristics. just because something can interbreed does not mean that it ever will in nature. even if they do cross in nature, they form their own distinct populations away from the place where they cross. in many cases, these hybrids are sterile, do not have an even number of chromosomes, or have different sized chromosomes in each pair.
also, the fact that certain plants can interbreed with a common relative does not mean they can interbreed with each other. for example, Grammatophyllum and Ansellia species have both been crossed with Eulophia, but there have been no successful crosses of Grammatophyllum with Ansellia. it would make no sense to include the three in the same species. exactly how they should be categorized is a matter of ongoing debate, and the recent re-classification is mostly due to recent studies of genetics. in some cases, this research shows that certain groups of species are more closely related than previously thought, and should be placed in the same genus or subfamily. this has led to attempts at creating new types of hybrids, which were at one time believed to be impossible. in other cases, the research has shown that species are not as closely related, and explains why certain types of hybrids are impossible. this same type of research is leading to re-organization of all plant families.

Very interesting! Thank you!
With other words, we will see many more changes coming.
Do you have any further information about the american orchids like Cattleyas, Laelias, Brassavolas and so on?
Where can I get updates about this research?

[lambelkip]

check here to see an argument against re-classification
check here to see information on one of the more recent studies.
there are several other articles on the subject, but I can't find them right now.

[kavanaru]

Originally Posted by bandeeorchids

In the animal kingdom a different species is an animal which is not able to reproduce with an other species from the same genus or in some cases they can but have sterile offspring.

Why in the Orchidaceae family is this not the case? We have hundreds of intergeneric hybrids which are obviously not sterile.

Does taxonomy has created the same mess within the trees family or within the grass family?

ok, just my to the topics, as the other have explained already a lot..

1.- you must keep in mind that taxonomy and systematics are living scinces which need to be revised with the appearance of new evidences and methods... yes, this can be confusing, especially for horticulture (but sometimes often for botanists!).
2.- The easiest part to understand regarding the merging of Brazilian Laelias with Cattleyas, is their separation from the Mexican Laelias. The genus Laelia was described for a mexican plant, therefore these are the ones who really belongs to this genus and the brasilian plants cannot be part of it, as it has been shown (actually, it was know since many years!) that they are not related.. Brazilian plants are more related to Cattleya...
3.- Regarding definition of species, Lambelkid has given a pretty good explanation. Now, you said that in animal species is defined whether they caninterbreed or not... This is not true... if you take Ducks, just an example, almost all of them can interbreed, and often the progeny is fertile too. This occurs in nature and in captivity! The genetic separation is not very strong, and these species stay separated by behavioral, niche and geographical border. Plants are a little bit more complicated regarding reproduction, and therefore you can easily find more hybrids in nature. as mentionned, many of them are infertile, but many others are not. In some cases the hybrid progeny is even stronger and better adapted to a particular environment, and therefore it would stay in the ecosystem (e.g. Ctsm. pileatum and Ctsm. macrocarpum produce teh hybrid Ctsm. xtapiriceps. The hybrid is better adapted to a particular environment in southernVenezuela, where it is even more abundant than the parent species)
4.- The "Mess" that you mentioned and "complain" about is not only present in Orchidaceae... youhave it in different taxonomic groups too. You must keep something in mind, botanists (including taxonomist and systematicists), but also zoologist, mycologist and so on, care about (among other things) the correct classification of the species, and this is revised every now and then... whether this makes easier or not the work of gardeners and horticulturist, is just rubbish.... they don't care about that, and that's correct that way! Horticulturist have two options, the yadapt to the new systems (and will always be behind it!) or just ignore it completely... Orchidists have decided to follow the taxonomists (in other plant groups they decided for the opposite, and for example they give names to particular clones and not to hybrids) and therefore must struggle with the changes you find form time to time... The Laeliinae case is an "easy" one...If you see Masdevallia, this is a more complex case.

[Orchidflowerchild]

Originally Posted by kavanaru

4.- The "Mess" that you mentioned and "complain" about is not only present in Orchidaceae... youhave it in different taxonomic groups too. You must keep something in mind, botanists (including taxonomist and systematicists), but also zoologist, mycologist and so on, care about (among other things) the correct classification of the species, and this is revised every now and then... whether this makes easier or not the work of gardeners and horticulturist, is just rubbish.... they don't care about that, and that's correct that way! Horticulturist have two options, the yadapt to the new systems (and will always be behind it!) or just ignore it completely... Orchidists have decided to follow the taxonomists (in other plant groups they decided for the opposite, and for example they give names to particular clones and not to hybrids) and therefore must struggle with the changes you find form time to time... The Laeliinae case is an "easy" one...If you see Masdevallia, this is a more complex case.

4. (b) Within life sciences, there is HEAVY pressure to PUBLISH PUBLISH PUBLISH...we live our lives in research through grants. We get grants by publishing notable studies. Some degree of nomenclatural redefinition must, of course, be chalked up to a desire to publish, either for personal notoriety or in desire of grants.

For my own part, i prefer a splitter's eye (see Castro & Chiron) on the laeliinae. And there are genetic analyses to support it (genetic classifications change WILDLY depending on what markers one uses). Too many, however, are disinclined to write Hoffmannseggella out on a tag.

As mentioned before though, horticultural and botanical interests are rather...divested, to be perfectly honest. It infuriates both the scientist AND the horticulturalist in me that RHS is being so quick to jump on what amounts to a bandwagon of scientific politics.

-Cj

[kavanaru]

Originally Posted by Orchidflowerchild

It infuriates both the scientist AND the horticulturalist in me that RHS is being so quick to jump on what amounts to a bandwagon of scientific politics.

-Cj

Indeed, I think the main responsability on the chaos created for horticulturist goes for the RHS... They are very reluctant sometimes to accept a new species or sub-species, but accept inmediately these kind of taxonomic changes (the reasons... those are to be discussed maybe in another thread). Even the scientific community does not accept these kind oftaxonomic changes as quick as the RHS has done. Normally, a change is propposed and it takes time until it is widely accepted by teh scientific community and well stablished. RHS has gone to quick changing (e.g.) Laelias to Sophronitis, to Hoffmannseggella, to Cattleya (if I recall it correctly there was also something like "Brasilaelia" in between), etc... But thi sis not the only case of chaos created by them.. You aso have plants accepted as species, while the the largest part of the community specialized in that plant are clear that it should be handled as a variety of another species or in extrem case (if you really want to be a very very purist) as a natural hybrid... but as Cj mentionned... politics are involved every where...

[tropterrarium]

One more thing to consider is, what is a species? So we enter the issue of species concepts, of which there are numerous. Biological species, morphological species, cohesion species concept, evolutionary species, species as lineage, evolutionary species, chronospecies, just to give a sampler here. There have been many, many books been written on just species concepts, I mean, the abstract idea of how one could define a species.

A plant species is defined differently from a living bird species, which is different from a fossil bird, which is different from a single celled eucaryote. One species concept does NOT fit all. That's why grad school takes a while to go through.

Now consider how much we struggle with the species concept. With genera (pl. of genus) it's a free for all. As long as they are clades=monophyletic groups, it's ok. How inclusive a genus is, that's an entirely open question with no objective answer. In my revisions/monographs, I use genera as a basket of species that occupy a similar sized morphospace, though that space is just in my head, nothing formal/mathematical.

And yes, this will not be the last change. Job security, yippee! [not for me though, at least not in orchids, I work on some other groups]. So just because it is published, does not mean it is right. Time will tell, and the court of scientific opinion is the arbiter.

[harleymc]

Taxonomists/cladists/systemicists don't concern themselves with artificial hybrids as such they only deal with a minority of orchid taxa in cultivation.
This has created the situation where splitters have identified several general within the old grouping of the Australian Dendrobium. However hybrids within these mini genera (let alone the hybrids between different mini-genera) are all (according to the International Orchid Register) dendrobiums which is considered an out group by the splitters.
So if I write for a biological journal about these species I might take the splitters on board but as a horticulturalist and hybridiser the bulk of my collection is outside the ambit of the cladists and taxonomists and therefore I'm not changeing my tags.