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Re: Sorry - Dryopteris affinis again?!

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  • Wim de Winter
    Dear Chris, You are undoing all my lobby-work to get the affines as species in the next edition of our national flora! I appreciate your rethinking the matter,
    Message 1 of 4 , Jun 3, 2013
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      Dear Chris,

      You are undoing all my lobby-work to get the affines as species in the next edition of our national flora! I appreciate your rethinking the matter, but the timing of it....

      But seriously, your new point seems to be that every fern with an oreades-wallichiana component in their genome should be considered as a single species. That would be a rather heterogenous species involving five (?) different genomic components in varying constellations. At least, since you'd include cambrensis, I assume you're not just lumping the O(O)W(W)'s, are you?

      I also wonder whether we are correct seeing any species at all in them. Why not  consider all of them as vegetatively reproducing hybrids? Even though the reproduction happens in the sex organs, its 100% somatic, no sex involved whatsoever. I don't think any biological species concept demands to recognize them as species.

      Wim
      (off line for the rest of the week)


      ..., Dryopteris affinis [groan, groan!].
      Originally I always treated the affinis group as one species, with subspecies within it, due to their generally similar morphology, impractically difficult overlap, and genomic relationship.
      But that came under fire from N. American "biological species" adherents, and Clive's amusement at tweaking it, and eventually I gave in and supported the main taxa as species. However I think, looking back on it after some decades away, that was very much a mistake - anyway less useful and appropriate, and personally I have returned to the single species treatment (with four subspecies in the UK, affinis, cambrensis, pseudodisjuncta and borreri).

    • chrisophilus
      Sorry Wim, I missed this one, due to Bhutan work. I think a lot of trouble comes in Botany from theoretical approaches to taxonomy where a certain supposed
      Message 2 of 4 , Jan 11, 2014
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        Sorry Wim, I missed this one, due to Bhutan work.  I think a lot of trouble comes in Botany from theoretical approaches to taxonomy where a certain supposed principle is hit on by an author and then attempted to stick to regardless of the degree of morphological differentiation and the different situations in different groups.

        My view is really one that follows the morphological history of the recognition of D. affiinis and all the Male ferns.  It is easy to see that all the affinis group taxa have a common morphology and form a clear entity on a par with other species in Dryopteris.  Then it is clear to me that all the subspecies etc. within D. affinis are morphologically very close and have a lot of overlap.

          They are all "the Scaly Male Fern", obviously, and going further is well beyond the level we are mostly used to for species.  In addition all appear to have OW in their genomic make up in various combinations (which explains why they are so close) - i.e. they are all closely related.  This seems to me the standard classic situation for subspecies within a species.

        I was a fool to succumb and make them species - and we then had everyone taxing themselves unnecessarily trying to distinguish inconstant piddling little local subspecies and varieties, applying ever more insignificant form nick-names - in what was basicly just a waste of their time and effort as it meant very little indeed.

        I do not know about any particular timing, it's just that I realised we had led people up the garden path, or I had!  But now with the single species D. affinis and the main subspecies only within it, affinis, borreri, cambrensis, persica, probably pseudodisjuncta, , possibly jessenii?, and pontica, then that makes a whole lot more sense and is a whole lot more practical as well as reflecting the biological situation of their relatedness.

        Apologies got mistypings - done by candle-light and my page-sixe has suddenly shrunk to a smaller reading size in my laptop, which I don't know how to put right and restore to a better size.

        Cheers,

        Chris., Kathmandu.

      • tony1church
        Dear Chris, Re: The Species and Subspecies in the Dryopteris Affinis Group I have read your essential and fascinating paper many times. Without it where would
        Message 3 of 4 , Jan 11, 2014
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          Dear Chris,

           

          Re: The Species and Subspecies in the Dryopteris Affinis Group


          I have read your essential and fascinating paper many times. Without it where would we be?


          As a non-professional UK based amateur botanist with a lengthy interest in the relatively abundant affinis group where I live I have to say that maybe it’s time we went through a more settled period with the group.


          There has been such a divergence of opinions on how many taxa we are dealing with and how they may be identified in the field that the non-expert may have become somewhat bemused by or even contemptuous of the professionals and given up!


          That would be a great pity because in many places the complex is a significant component of the vegetation and can with a bit of effort be sorted into at least the three main ‘species’ as is widely accepted now. Granted this needs a fair amount of practice.


          On the other hand those with limited interest in the group or lacking opportunities to increase that understanding of the group through field practice are obviously better off simply recording what they see in the field based on the relatively straightforward distinction in most cases between the presence or absence of the ‘black spot’ and putting it down on a recording card as D aff agg. or D filix-mas.


          Could I make a special plea here that you stick with the present hierarchy of species and sub-species as laid out in your paper which has, to me anyway, for many years seemed the appropriate way to deal with the complex. It works very well here on the Isle of Arran as long as the problems associated with D. borreri complex are left for further research. I suspect the same applies throughout a good deal of the British Isles and probably further afield. I find that they are very distinctive and on the whole are not to be confused as long as one has put the effort in. This is especially true of D. affinis and D cambrensis, at least where Arran is concerned.


          Is it reasonable to suggest that there is a parallel here between the group and say, brambles or even whitebeams? Arran even had it’s own nature reserve established in the 1950s for Sorbus arrenensis and S pseudofennica which are also apomictic species and supposedly the result of hybridization that have become ‘fixed’ by apogamy. As for brambles, well we all know there are umpteen micro-species. Here on Arran we have 20 named species and with practice they are separated without difficulty most of the time. And what about the Hieracia and Taraxacum?


          May we not, eventually, recognise a fair number of ‘fixed’ apomictic species within the Scaly Male-fern or Dryopteris affinis agg?


          A second point also occurs: I can’t help noticing too that nearly all of the discussion seems to be about morphological distinctions. It had been clear to me for many years that there are distinct ecological differences between the three ‘species’ involved.


          In my case having lived for many years on Arran, a fairly small, sheltered, diverse island, at least at lower levels, off the west coast of Scotland. It rises to sub-alpine levels at just under 900m but the higher hills are uniformly base poor granite. Dryopteris affinis agg is frequently abundant on lower ground where grazing pressure permits especially in sheltered woodland. It’s only rare on boring over-grazed moorland that covers perhaps half of the island. Usually, near sea level there are several taxa involved often growing inter-mixed but there are subtle ecological factors involved. This is what I have found:


          D affinis: dominant for instance at very low altitudes in semi waterlogged sheltered woodland almost at sea level; frequent on moderately fertile stream banks, ditch sides including conifer forestry drainage channels usually where there is woodland cover. Seems to thrive where there’s a fairly constant flow of moisture through its root system. Generally avoids very acidic and drier environments. Much less frequent in open well drained sites such as roadside verges. Restricted to an altitude limit of c100m


          D. cambrensis: not restricted to but the only taxa of the group that tolerates acidic environments such as schistose or granitic scree and rock ledges as one might expect from it supposed D oreades genetic input. It is the commonest and most widespread taxon on the island from sea level to near the highest tops (to at least 750m) where it occasionally occurs on sheltered ledges and talus slopes out of grazing reach of abundant red deer. Very frequent on open roadside banks and verges.


          D borreri: Widespread, but in most of the island the least common taxon (and importantly the most variable by far which is perhaps the reason for a good deal of confusion!). The typical form has a preference for drier, well drained sites and most tolerant of less acidic sites or perhaps a preference for basic/calciferous site in this geographical area, much the same as D. filix-mas. May ascend to as much as 300m ASL (but those I’ve seen at higher altitude may have been misunderstood for D cambrensis ssp pseudocomplexa – and more on that taxon at some other time!)


          And with that, Chris, I think I’ve said enough for the time being. I send this hoping I haven't got too much wrong!


          With a great deal of respect,


          Yours,


          Tony Church



          ---In uk-ferns@yahoogroups.com, <chrisophilus@...> wrote:

          Having been led to the UK ferns group by the Stenochlaena/Acrosticum mystery that came to my e-mail, perhaps I could take the opportunity to ask about that old chestnut, Dryopteris affinis [groan, groan!].
          Originally I always treated the affinis group as one species, with subspecies within it, due to their generally similar morphology, impractically difficult overlap, and genomic relationship.
          But that came under fire from N. American "biological species" adherents, and Clive's amusement at tweaking it, and eventually I gave in and supported the main taxa as species. However I think, looking back on it after some decades away, that was very much a mistake - anyway less useful and appropriate, and personally I have returned to the single species treatment (with four subspecies in the UK, affinis, cambrensis, pseudodisjuncta and borreri).
          It also means that I do not see the value of tiddly forms being named, and causing everyone a lot of pointless exertion searching for individuals that could be called 'rhombidentata' or 'wallichioides' or an array of other names applying to a snapshot taken from the range of form in the subspecies. I am not going to try to use minor form or var names any more - and am dumping some my own semi-geographical ones, some of Ken's and mine, some (apologies!) of Anthony's, and some going back to Hugh Corley. I just don't think they are taxonomically significant enough to merit naming and diverting people's energies into trying to put names onto small clones of individuals that occur here and there.
          I hope this would not cause outrage, rather that it may cause a sigh of relief, instead? Would this be acceptable in general to our readers?
          I am back in Kathmandu now after 7 months study in Edinburgh, the BM, and Kew - so much information to assimilate on all fronts, I need another lifetime!
          All the best,
          Chris Fraser-Jenkins.
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