Scottish Rock Garden Club Forum
Bulbs => Bulbs General => Topic started by: Robert on April 14, 2014, 04:26:48 PM
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Trillium chloropetalum-I think
Philip,
I enjoy seeing our California native Trilliums. Around here they are still fight over the T. angustipetalum - T. chloropetalum issue. Who is what, or are they all the same! ????
:P That is what I think. They are all beautiful. Thanks for sharing your beautiful Trillium.
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Robert,
Based on the molecular data angustipetalum, kurabayashii, albidum, and chloropetalum are all the same species! I should know since I ground up all these species, extracted the DNA, and sequenced a lot of the chloroplast data we've looked at. BUT, based on morphology there are at least 3 good species out west. Given more samples and more molecular sampling I am sure we can tease apart all the name species out west. So far the DNA is teasing apart the eastern species far easier.
Aaron
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Aaron,
I know that it is way beyond the scope of this forum to go too far with this discussion, however I do have a few questions.
First I want to make it clear that I am farmer, by trade, with no special training.
One way I guess at the relationships of different plant species to each other is through their breeding characteristics. I am not familiar with the breeding characteristics of Trilliums, but I do know a little about primulas. To my understanding DNA studies have revealed that Primula and Dodecatheon are of the same genus. To my understanding there are so many chromosome nonhomogenies that one can not cross a Dodecatheon with a Primula, yet they are considered to be in the same genus. Very puzzling to me.
I know a little more about the breeding characteristics of the genus Rhododendron. Is Ledum a Rhododendron or a Ledum? Ledum crosses easily with other tetraploid Rhododendrons, yet what do the DNA studies reveal? It seems that there is still no agreement.
And if one wants to get absurd, my understanding is that humans share 95% or more of the same DNA as a chimpanzee. At what point are we human or chimpanzee? Are there so few chromosome nonhomogenies between humans and chimpamzees that in a Dr. Strangelove way we could cross the two?
I certainly mean no disrespect in any way, however who is deciding all of this? It seems crazy making to me!
Do you have any basic book references? I prefer college text books, no internet please. Through Worldcat our library can get almost any book.
Thank you so much.
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I know a little more about the breeding characteristics of the genus Rhododendron. Is Ledum a Rhododendron or a Ledum? Ledum crosses easily with other tetraploid Rhododendrons, yet what do the DNA studies reveal? It seems that there is still no agreement.
Robert - Funny you should mention it. In the RHS Rhodo., Camellia & Magnolia Grp. issue this month there is an aricle by Barry Starling - "Ledum astray". It's worth a read.
johnw - 17c here this afternoon, Ann Christie no doubt was in her swimsuit.
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It all depends on the taxonomist. Some people like broad groups (Dodecatheon and Primula as one) or very small groups. Any recent book on molecular systematics is good. Some better than others, but all should give a good overview of the basic premises.
As far as DNA similarity is concerned sometimes 3% difference is enough for a new species, or for a new genus, or sometimes the same species!! In the end, I think considering all evidence is important and not just the DNA which has been fairly limited in some cases. Breeding is one thing, but with some of the eastern sessile Trillium many of them do not seem to be able to cross and produce fertile offspring. This might be better applied to animals where offspring are produced but are sterile. Cytological homology is sometimes used to define genera, but then with the group I am studying (Polygonatum) the species have a range of base numbers from 9-15 with the sister genus (Heteropolygonatum) with 16! So why cut that one out as a new genus? Who knows, but it does have at least one unique morphology in that the tepals are imbricate rather than valvate. But, again other clades in Polygonatum have unique characters as well.
Which brings it back to the taxonomist and the choice they make in what to recognize. I prefer the method that creates the least amount of nomenclatural problems.
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Aaron,
I know that it is way beyond the scope of this forum to go too far with this discussion,
Is it? I find it fascinating, but I know taxonomy drives many forumists to distraction! Maybe create a separate taxonomy topic so only those who are interested need read it?
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Robert - Funny you should mention it. In the RHS Rhodo., Camellia & Magnolia Grp. issue this month there is an aricle by Barry Starling - "Ledum astray". It's worth a read.
Where can I find a copy?
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Is it? I find it fascinating, but I know taxonomy drives many forumists to distraction! Maybe create a separate taxonomy topic so only those who are interested need read it?
Excellent suggestion - it is done.
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Great! Lets get confused ;D
An image of 1, 2 or 3 species of Trillium?
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It would be very interesting if there was a comparison study of the DNA from Rhododendron occidentale in its coastal range where it lives side by side with R. macrophyllum and the population of R. occidentale from the Sierra Nevada. Direct family lines can be traced back through the cytoplasmic DNA. R. macrophyllum and R. occidentale can and do cross in the wild. I have a strong hunch that this relationship would show up in the cytoplasmic DNA of the coastal population of R. occidentale. The populations from the Sierra in my mind would show a far more distant relationship. What if cytoplasmic study shows that R. macrophyllum was "mommy" for some, many or maybe all of the coastal population of R. occidentale? This seems completely possible to me, and seems to create taxonomic problems.
I have some of the same questions with our native lilies. I see natural hybrids all the time in the wild. In some areas there is a gradual change, as one move up the mountain, from what we know as L. pardalinum, to something in between, to L. parvum, with L. humboldtii sometimes mixed in. This brings up many questions for me with DNA sampling, as well as many other questions.
As a farmer, what am I to think of the relationship of Zea mays to teosinte? I work a lot with Cucurbita pepo. I wonder how much genetic drift there has been from the wild species? Are the cultivated varieties now a new species?
As a farmer and gardener I'm not convinced or comfortable with the change. DNA shows the relationships to each other, the rest is a human contrivance.
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Robert - Funny you should mention it. In the RHS Rhodo., Camellia & Magnolia Grp. issue this month there is an aricle by Barry Starling - "Ledum astray". It's worth a read.
johnw - 17c here this afternoon, Ann Christie no doubt was in her swimsuit.
John,
Yes I did read Mr. Starling's article. Yes, it is worth a read. Thanks!
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For those of you who are interested in how ideas change, there was an interesting article a few years ago in Technology Review about how new research is get some to rethink the ideas of Lamarck. These ideas were rejected 100 years ago by Bateson, etc. and now some are saying "hold on" maybe there is something to Lamarck's ideas. It is worth the read. Sorry, I no longer have that issue but I know it was in the past 6-7 years. The scientist worked out of Seattle. A clue for those that might want to read the article.
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Follow up to Trillium taxonomy.
First I would like to state that I am extremely supportive of the DNA study of our California native plants.
I checked with some of my friends who are frequently out in the field and have been observing our native Trilliums for many years. We still have many questions. From our observations it is not surprising to find that T. chloropetalum and T. angustipetalum could be the same species, after all, they were lumped together in the past.
Regarding T. albidum being lumped with the T. chloropetalum / angustipetalum complex we still have many questions. DNA testing only reflects the DNA from the samples taken. There is considerable variation in the habitat within the range shared by T. albidum and T. chloropetalum / angustipetalum. There are differences north to south within their range as well as on canyon slopes where habitat can change dramatically in less than a mile with up to a 2,000 foot elevation change. In addition, there are the changes in the habitat from logging and fire suppression. All of this could effect the mixing of the species.
We all agree that there is evidence to suggest that there could be natural hybridization taking place between T. albidum and T. chloropetalum / angustipetalum. We also agree that there could be "pure" colonies of T. albidum at the higher elevations, isolated and away from the hybridization zones.
Unfortunately, none of us are in any position to do DNA sequencing ourselves and have never been asked to provide Trillium samples. Without more information it does not seem reasonable for us to lump T. albidum with T. chloropetalum / angustipetalum. Some possibilities are that there could be hybridization taking place and /or that there is a white form of T. chloropetalum / angustipetalum that is confused with T. albidum.
Changes in interpretation are frequent in science. It will be interesting where this all goes.
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To follow up on Robert's thoughts, an important part of the story that is usuallly ignored is what the insect pollinators see when they look at a flower. Since many insects have the ability to perceive light farther in to the ultraviolet end of the color spectrum than humans, flowers that look to human taxonomists to be plain (such as all white) may actually have features we are not able to see. In other words, just because a flower looks white to us does not mean that the flower does not have taxonomically significant pigmentation that would differentiate it from other "white-flowered" plants. This might explain "white Trillium angustipetalum", or "white Erythronium revolutum".
It is possible to take photos that capture the ultra-violet part of the spectrum, but it takes special equiplment. As I understand it, most digital cameras have a filter that prevents ultraviolet wavelengths from reaching the sensor.
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A couple of links to papers on this subject of pollinator vision:
Dissecting pollinator responses to a ubiquitous ultraviolet floral pattern in the wild
Matthew H. Koski* and Tia-Lynn Ashman
- there is an image on the summary page of this link
http://www.functionalecology.org/view/0/summariesarchive.html#koskiashman (http://www.functionalecology.org/view/0/summariesarchive.html#koskiashman) - "Image caption: Flowers of Argentina anserina in the human-visible spectrum (top) appear uniformly yellow, however in the UV spectrum (bottom) flowers display a distinct bullseye pattern."
On this page: http://www.nature.com/scitable/knowledge/library/perceptual-worlds-and-sensory-ecology-22141730 (http://www.nature.com/scitable/knowledge/library/perceptual-worlds-and-sensory-ecology-22141730) - there is -
Figure 3: Comparison of a Mimulus flower under both white light (left) and UV light (right)
Note the dark central area in the UV image. This will guide the bee to the area where nectar can be found, while also ensuring that the bee is passing the structures that will cover it with pollen.
This talks of the uv spectrum as well as electric charges.....
http://www.npr.org/2013/02/22/172611866/honey-its-electric-bees-sense-charge-on-flowers (http://www.npr.org/2013/02/22/172611866/honey-its-electric-bees-sense-charge-on-flowers)
edit : some more :
Flowers in Ultraviolet - Arranged by Plant Family Photography by Bjørn Rørslett/NN
http://www.naturfotograf.com/UV_flowers_list.html (http://www.naturfotograf.com/UV_flowers_list.html)
http://www.nature.com/scitable/blog/the-artful-brain/alternate_realities (http://www.nature.com/scitable/blog/the-artful-brain/alternate_realities)
http://web.ncsu.edu/abstract/science/wms-what-bees-see/ (http://web.ncsu.edu/abstract/science/wms-what-bees-see/)
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All this discussion has certainly inspired me to do more field work, especially with our native Trilliums. Plants that are different always seem to show-up. ...and in nature, everything is in constant change. I wish that I had field notes from my travels 45 years ago. I'll keep everyone posted on what I find. ;)
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Do you have any basic book references? I prefer college text books, no internet please. Through Worldcat our library can get almost any book.
Robert,
A book that might be of interest to you, which is reviewed in the most recent issue of Castanea, is "Tree Thinking: An Introduction to Phylogenetic Biology", by David A. Baum and Stacey D. Smith. It was published in 2012 by Roberts and Company Publishers. The review is generally positive and it sounds like it is designed to be an introductory college level textbook on the topic.
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Robert and others,
I agree that hybridization may be more of a problem in the western NA Trillium. One problem I see is that T. chloropetalum seems so variable, but we do not have the necessary nuclear markers yet to test for parentage. Also chloro- is green and most of what people call chloropetalum has those reddish petals. The type specimen is clearly a greenish flowered plant. Maybe the type was from a hybrid zone?
In our lab we are happily accepting material of any sessile Trillium with documented provenance! We just got T. petiolatum this week and will have far more sequence data soon compared to previous phylogenies that have utilized only matK and rbcL, neither of which provide any species level data in Trillium. We do have three whole chloroplasts for Trillium and may end up with a lot more given time and money. Our first phylogeny was published last year and the description of a new species, T. tennesseense, which is pictured in my previous "quiz" post (on the far right). It is morphologically similar to T. oostingii (the two left plants), but also easily separated from it by morphology, DNA, and fragrance (as well as distribution). We are preparing to describe the Ruby Falls Trillium and yet another species from Georgia (USA). That first phylogeny only had T. albidum from the West included in it. Our current phylogeny that we are preparing to publish has far more sampling of the western NA species; 3 albidum, 1 chloropetalum, 1 parviflorum, 1 angustipetalum, and 1 kurabayashii. We are always happy to accept more. This spring we have added over a dozen new populations of southeastern sessile species in an attempt to sort out the lancifolium complex and also many more samples of cuneatum.
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Aaron,
It seems that more field work with the Western Trilliums could be a good. How our thinking about them has change over the years. Our ideas in science can and do change all the time as new information becomes available. Take a look at the California Floras by (Willis) Jepson, 1960 or (Philip) Munz, 1959.
If I find any Trillium colonies that seem like they could be significant I will post photo(s) on the forum.
Also, thanks for your input. I may never be able to get up to speed on some of the science, after all I'm a gardener, but all this does prompt me to take a closer look at the whole situation and sharpens my skills in the field.
And how will the DNA testing be used to determine Subspecies and/or variety status? I hope that something can be worked out that is workable for us gardeners too. As a general question, in addition, Is anybody in the general horticultural world consulted in these decisions?
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Thanks for answering your quiz question, Aaron. I am sure we have all been wondering.....
All I could say is that I know enough not to know!