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Post by cabintom on Nov 8, 2014 8:09:46 GMT -8
This is a general question. How is something determined to be a subspecies of a nominate?
Frequently I'm seeing identifications based solely on the location where the specimen was caught because visually subspecies are nearly identical. So, if they are essentially the same how is it determined that they are separate subspecies?
Thanks!
Tom
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Post by wollastoni on Nov 8, 2014 8:49:45 GMT -8
Subspecies should be DNA/morphologically different with some clear and recurrent differences. On some difficult genera though, you need a trained eye to see the differences (like on Delias aroae subgroup)
Some ssp are "wrong ssp" as they did not really differ from the nominate or from other ssp.
Many ssp have been overdescripted on some difficult genera like Parnassius.
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Post by nomad on Nov 8, 2014 9:39:47 GMT -8
I always have found it fascinating how subspecies are interpreted by different authors. For me there has to be good differences between the nominate and any subspecies. Mountains ranges on islands in the Australian Region often hold many different and bona fide subspecies. However, when a subspecies differs from the nominate in such a degree, when does it become a species in its own right. Again many authors disagree. DNA is often mentioned and touted. How to use DNA in Natural History scientific work has been known for quite a while now, I have not seen any fruits of its use , can it really work with insects such as butterflies. If yes, then why are we not seeing any of the results? There are many names in use for geographical variations especially in the much sought after Birdwings and Parnassius, a new race sells well.
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Post by africaone on Nov 8, 2014 11:22:41 GMT -8
there "some kinds" of subspecies and in the doubtfull ones, the named "commercial subspecies"  |
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Post by cabintom on Nov 8, 2014 12:16:10 GMT -8
there "some kinds" of subspecies and in the doubtfull ones, the named "commercial subspecies" That doesn't seem very scientific. Is there not some kind of specific definition for a "species" or "sub-species"? |
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Post by nomad on Nov 8, 2014 13:39:33 GMT -8
there "some kinds" of subspecies and in the doubtfull ones, the named "commercial subspecies" That doesn't seem very scientific. Is there not some kind of specific definition for a "species" or "sub-species"? It seems all you need to establish a subspecies or a species, is have it published in a scientific journal or book. Thus some taxonomists may believe in your new subspecies, while others may not. Hence when writing a book on butterflies it is up to the author concerned. The same with genus names, some taxonomists simply cannot leave them alone, they are always looking to introduce new ones, even those that have been in existence long before they were born. As our peers will never agree, its left to the humble collector to form his own opinion. |
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Post by bobw on Nov 8, 2014 14:05:05 GMT -8
This is a very difficult question and there are many different views as to what constitutes species and subspecies. The traditional definition of a species (at least in Lepidoptera) is that when two individuals pair, the offspring are fertile; i.e. if individuals from different species pair, whilst the offspring may be viable, they are not fertile. However, there are some taxa that are almost universally recognised as species that can produce fertile offspring, e.g. Colias philodice and C. eurytheme; that disproves the theory but in most cases it still holds true. I once asked Gerardo Lamas, who is better qualified than most, for his definition of a species and his (only partially flippant) reply was that a species is whatever a competent taxonomist says is a species.
The definition of a subspecies is even more difficult. Different subspecies belonging to the same species should produce fertile offspring, but this doesn't always hold true when they've been separated for a long time - they may often have adapted to different foodplants and be well on their way to becoming full species. The most important thing is that subspecies must have been genetically isolated for a long period of time, although this can be complicated by changes in their environments allowing them to meet again. There should probably also be some way of separating them phenotypically, at least in long series.
In the final analysis everyone has to form their own opinion, although in general most people will follow any acknowledged specialists in particular groups.
Bob
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Post by eurytides on Nov 8, 2014 17:10:01 GMT -8
This is a complex question, but the bottom line is that nature just doesn't fit neatly into human made "boxes". When you ask if there is a scientific definition for a species - sure, there are several. One of the more traditional ones is that members of the same species can mate and produce fully fertile offspring. Does this work 100? No. Take orchids for example. Most of the store bought orchids are complex hybrids of several "species", all of which produce fertile offspring (to varying degrees, but some are pretty much 100%). If you have two lep species that are separated by some mountains and never meet in the wild, but will produce 100% fertile ova in the lab, are they the same species? Scientists say yes, but in nature, it's a no. So, it's a complex story, and like the others have said, there are other reasons to name species or subspecies (commercial gain for example). Even using DNA analysis, just where does one draw the line between "species" on what's really a continuous spectrum? Humans and chimps share 98% of our genes....we're different. There are many types of bacteria that have to differ a lot more genetically to be considered species. I think in the end, there's always going to be an element of human bias and "opinion" on the matter of species (subspecies is even worse).
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Post by Adam Cotton on Nov 9, 2014 9:35:47 GMT -8
As a quick guide for Tom after the last 2 excellent posts, Lepidopterists often use an 80% rule to determine whether two subspecies should be treated as valid or not. If at least 80% of the specimens in a population show the differences in phenotype (normally colour pattern) that define the subspecies then they constitute 'good' subspecies. That does mean that up to 20% of individuals may actually look more like or identical to those of another subspecies. That's why it is not a good idea to base a subspecies on a single specimen.
Adam.
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Post by exoticimports on Nov 10, 2014 6:53:56 GMT -8
You know it's a new subspecies if:
1. There's an extra dot on the hindwing
2. The data says it came from a location at least 10km from known locations
3. It has any sort of purple sheet to it
4. The genitalia can be smooshed into a shape resembling Jesus
5. It came from Russia, Cameroon, or near Chernobl or Three Mile Island
6. It's from a national park in USA
7. The Chinese dealer said it is
8. It burns a different color than other similar specimens when thrown in a fire
9. You're at an insect show
10. There's even the most remote chance you can make money off it
Chuck
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Post by cabintom on Nov 10, 2014 7:17:10 GMT -8
This ls all very interesting. As a scientific line of study, I had assumed there would be well defined and clear definitions for important terms/classifications like this.
I'm curious, is this something you all expect will sort itself out in the long run? (Or would you say things are fine the way they are?)
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Post by wollastoni on Nov 10, 2014 7:59:42 GMT -8
That's also why taxonomy is so interesting.
Revising some difficult groups like Parnassius (moutainous species) and Delias (mountainous + island species) is passionating and defining the limit between true sp and true ssp is a very difficult science/art on such groups.
All SERIOUS taxonomists with who you will talk will tell you : "I am not 100% sure but I think that..."
All those who will tell you " it is obvious that" are bad taxonomists to me.
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Post by nomihoudai on Nov 10, 2014 8:26:39 GMT -8
Chuck, I'm rolling on the floor from laughter.
Tom, an answer is difficult to give. I could now recite one of the 270 definitions used by 500 different taxonomists (numbers made up on the fly) but I guess this will not really sort out the matter or be in any way what you are looking for. Yes in this regard taxonomy IS subjective and has NOTHING to do with a science. You can define criteria which employ methods commonly used in science but this doesn't make it reproducible or objective in any way. I can use a brush but it doesn't make me a painter... so for me any definition I have seen so far has been rather frustrating. I do engage in taxonomic work, so far I just go by nomenclature rules, so some names are already by definition wrong or unusable. I disregard these and regard them as synonym/homonym or whatever they may be. All the other names I will try to keep track off until I come up with a working concept. So much for my personal, yet again subjective, thoughts, but maybe they are of use to you. They are also very brief as any text going into details would result in a whole book...
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Post by eurytides on Nov 10, 2014 16:47:32 GMT -8
I don't think this will be sorted out. I think all life is inherently "fluid" and there's no way everything will all fit nicely into our "boxes". Take Papilio zelicaon in California. A couple of centuries ago, they were pretty much all univoltine. Now, many populations in lowland California have switched to Citrus or fennel (introduced). Because these are plant species that are available to support larvae year round, the populations that eat Citrus or fennel have become multivoltine. Is this enough to be a different "subspecies"? What if over many generations, they really diverge from the univoltine population and cease to interbreed? Things are always changing...what we call species or subspecies is only even applicable on short geologic time scales.
Would I like things to fit neatly and discretely so that my specimens labels never have to change? Of cousre! Is that reality/feasible? No. It's nature, and I try to just learn as much as I can.
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Post by trehopr1 on Nov 10, 2014 20:56:55 GMT -8
Exoticimports, my sides are hurting from laughter......
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