Slipper orchid evolution: does anyone care?

[Braem]

It is nice and cosy in my newly furbished office and I am getting the heat out of the outside air. No gas, no oil, just air! And it is about 54 F in Lahnau on this 8th of December!

Guido

What's the weather like in Oslo today?

We had a high of 35 until the front went through, and tonights low is supposed to be 16:sob:


I'll be burning propane tonight!!

 

[Heather]

Finally, it is unpleasantly cold here this morning, only 18°F.

 

[NYEric]

I closed the windows in the front room [with the plants] because of the forecast - teens and windy - and it got so warm from the heat I had to open a window for a while to air out. NYC: Sunny and cold.

 

[VAAlbert]

...it would be of special interest that you explain the methods used and explain what the results of those methods tell us, and what they don't tell us.
Guido

OK, sounds great! I'll explain everything I can, and as simply as possible. It will help me focus this discussion if you all could ask some specific questions that you may be wondering how/if/what can be done. Remember, I am not specifically doing genomic, molecular developmental, or population genetic work on slippers now, but instead on other plants.

However, just since joining this forum, we have started to try getting some more DNA sequence data to help corroborate / not corroborate our previous phylogenetic work re: the placement of Mexipedium! Results from broad taxonomic sampling have so far been published for only one locus (gene, or if not a gene, some specific DNA region), and the alignment of the DNA sequences (the bases A, T, G, and C -- very important!) was ambiguous & perhaps unintentionally biased, not to mention the fact that the analysis presented in the paper (Cox et al.) was not done as well as it could have been. Specifically, the application of the particular character weighting procedure has now been shown to to be flawed and no longer applicable to any data. Regardless, even without that procedure, Mex stays where Cox et al. put it (just as where I put it in 1992 in my Mex description paper, using yet another locus).

But the jury should remain out, and I hope we can get a few more loci to add to the question.

Regarding more data on species-level issues, this will depend on how much information new sequences could provide. No promises for either the Mex goal or this possibility; we are working on 'side money' from a grant to do other research, so our expenditures will have to be limited. Plus, there's no guarantee we can actually obtain new sequences that will provide meaningful enough amounts of evolutionary divergence between them.

I'll be happy to talk more about other topics; please try to help by throwing some out for me.

By the way, the weather here is unseasonably mild, and we have had nothing but rain for the last 2 weeks! There is snow in the mountains, of course, but in Oslo we get the 'maritime effect', but usually not this late in the season.

All best,

Vic

 

[Braem]

Victor,

excellent, lets keep this discussion going. I will certainly come up with some questions. I would love to see the new results.

I think, however, that very few people on this forum are familiar with genetic terminology (please correct me if I am wrong). Therefore, it may be good to explains the basics first.

regards
Guido

OK, sounds great! I'll explain everything I can, and as simply as possible. It will help me focus this discussion if you all could ask some specific questions that you may be wondering how/if/what can be done. Remember, I am not specifically doing genomic, molecular developmental, or population genetic work on slippers now, but instead on other plants.

However, just since joining this forum, we have started to try getting some more DNA sequence data to help corroborate / not corroborate our previous phylogenetic work re: the placement of Mexipedium! Results from broad taxonomic sampling have so far been published for only one locus (gene, or if not a gene, some specific DNA region), and the alignment of the DNA sequences (the bases A, T, G, and C -- very important!) was ambiguous & perhaps unintentionally biased, not to mention the fact that the analysis presented in the paper (Cox et al.) was not done as well as it could have been. Specifically, the application of the particular character weighting procedure has now been shown to to be flawed and no longer applicable to any data. Regardless, even without that procedure, Mex stays where Cox et al. put it (just as where I put it in 1992 in my Mex description paper, using yet another locus).

But the jury should remain out, and I hope we can get a few more loci to add to the question.

Regarding more data on species-level issues, this will depend on how much information new sequences could provide. No promises for either the Mex goal or this possibility; we are working on 'side money' from a grant to do other research, so our expenditures will have to be limited. Plus, there's no guarantee we can actually obtain new sequences that will provide meaningful enough amounts of evolutionary divergence between them.

I'll be happy to talk more about other topics; please try to help by throwing some out for me.

By the way, the weather here is unseasonably mild, and we have had nothing but rain for the last 2 weeks! There is snow in the mountains, of course, but in Oslo we get the 'maritime effect', but usually not this late in the season.

All best,

Vic

 

[SlipperFan]

...Therefore, it may be good to explains the basics first.

I, for one, would appreciate that! My background is in art and photography, not science, but I find this interesting.

 

[ScottMcC]

I think that both of the esteemed doctors should make new threads explaining the basics of their respective subjects. I've got a BS in Biochem, an MD, and a wife who's a few months away from her PhD in biochem, and a fair number of the things that have been discussed have been way over my head.

So please, if you could both start new threads explaining the main "tools of the trade" in taxonomy and genetics (at least the parts of both fields in which you're involved), I'd really appreciate it. No need to dumb things down, just start at the beginning--assume that I'm semi-competent at absorbing information.

 

[Heather]

That would be nice, actually, for all of us and especially any members who might be feeling a bit intimidated by these threads.

 

[Braem]

Scott,

the problem is that we certainly have a mixture on the forum (and this is not meant to be an insult to anyone) I don't want to dumb things down for anyone, but to be sure, we might have to start pretty basic. I hope Victor comes in on this, and maybe Victor and I can agree on a procedure off forum. (Victor?)

The easier thing (I think) would be that you people ask specific questions, and I for my part will then try to be as explicit as possible.

regards
Guido

I think that both of the esteemed doctors should make new threads explaining the basics of their respective subjects. I've got a BS in Biochem, an MD, and a wife who's a few months away from her PhD in biochem, and a fair number of the things that have been discussed have been way over my head.

So please, if you could both start new threads explaining the main "tools of the trade" in taxonomy and genetics (at least the parts of both fields in which you're involved), I'd really appreciate it. No need to dumb things down, just start at the beginning--assume that I'm semi-competent at absorbing information.

 

[Braem]

Heather,

no one should be intimidated by these treads. We alls have different backgrounds and all have different levels of education etc. That is nothing to be ashamed or afraid about. I, for my part am a complete nut when it comes to maths, computers (and many other things). But then. I am a good general biologist, a good botanist, and I am pretty good at Art History and English literature, and I managed to keep a wife over 32 years ... (poor girl). Not bad for a young lad like me .

Guido

That would be nice, actually, for all of us and especially any members who might be feeling a bit intimidated by these threads.

 

[Rick]

Hi again,

Thanks for your input Kentuckiense! BTW, re: the above, 2 things:

- I don't mean to say that Barbata Paphs don't occur in the same geographic regions, but it seems to me that they usually occur isolated from one another in terms of 'microgeography', e.g., even elevation on the same mountain, or on differnt rock substrates on the same little peninsula.

- A 'radiation of forms', such as we do see with the barbatas, and yes, to a degree, with their staminodes, need not be an 'adaptive radiation'. Evolutionary change, and fixation of new morphological forms, can certainly take place in the absence of natural selection on those forms.

The latter is is in fact exactly what I'm working on with the Hawaiian endemic mints! Such radiations can occur by random chance, when certain alleles (versions; mutants) of different genes become dominant in small populations simply because the small population size favors the fixation of any mutant that comes up, be it a 'good' one or a 'bad' one. Random changes like these can of course become the subject of natural selection LATER, and this has certainly happened in some other systems.

So, while the barbatas are probably pollinated by flies, they need not be pollinated by different species of flies, or even be adapted to different species of flies; the Barbata species could simply be isolated from one another by space or even flowering time, and their distinct (sometimes!!!!) morphologies amongst each other could be 'frozen accidents' of seed dispersal and fixation of new genotypes.

For example, Paph curtisii(/superbiens) can co-occur with Paph tonsum, and the natural hybrid is known. Reproductive isolation can be leaky, and bugs can go after whatever they find.

Clearly more to talk about here - I'm having fun!

All best,

Vic

After checking out a bunch of pictures of aphid colonies it occured to me I can see a clear resemblance of the pimply/warty area of the pouch behind the staminode of many barbata species. This pimply area is especially prominent in wardii, sukhakulii, and dayanum. After spending just a few minutes looking up natural history of aphids, there seems to be allot of aphid species specialized on certain species of plants.

This provides another hypothesis that barbata are still mimiciing other plant species by mimicing an infected segment of these plants.

This is pretty wild!!

 

[VAAlbert]

Fascinating! If you can compile some photos and even try to match them up with a Paph or two, that would be really neat to see.

Re: discussion of evolution, taxonomy, genetics, etc., some of the interchanges we've had on these threads have been a little complex, I admit! But many of these have been specific chats betw. me and certain other folks, and although I can hope you've been interested in reading them over, I surely understand if they haven't given you much to go away with.

As I've indicated before, I think the best way to proceed on a simpler, more explanatory level would be if any of you guys could throw out as specific questions/topics as possible. It'll be hard for me to address questions like 'what can genetics do for understanding slipper orchid evolution?' since this is such a broad, multifaceted topic. If you were to ask something like 'How could you use genetic data to understand why Paph delenatii and Paph wardii petals look different?', even though that's also complicated, I could begin to narrow things down and try to start at the basics for such a point.

I'm very happy to talk about taxonomy and nomenclature as well.

Please don't be intimidated! There's lots to talk about, and lots of levels to talk about stuff at! :rollhappy:

All best wishes,

Vic

After checking out a bunch of pictures of aphid colonies it occured to me I can see a clear resemblance of the pimply/warty area of the pouch behind the staminode of many barbata species. This pimply area is especially prominent in wardii, sukhakulii, and dayanum. After spending just a few minutes looking up natural history of aphids, there seems to be allot of aphid species specialized on certain species of plants.

This provides another hypothesis that barbata are still mimiciing other plant species by mimicing an infected segment of these plants.

This is pretty wild!!

 

[gonewild]

Do you have an assumption as to how many years (or time period) orchids with pouches have been evolving.
How much time is represented in the genetics you are looking at?
Are there fossil records of orchids with pouches?

 

[Braem]

Lance et alia,

as far as I know there is no fossil whatsoever that can be determined positively as being an orchid. Some decades ago, there were a few things published as "orchid fossils". In fact, they could have been just about anything you want to imagine plant like.

The (time) origin of the "appearance" of flowering plants is under debate. About five years ago (I am doing this from memory, so don't nail me down on a few years) there was an article in "Nature" or "Science" (I must have it somewhere) about a fossil plant from which the authors deduced that it was a flowering plants more than 100 million years old.

All about the molecular genetics, I will leave to Victor.

Guido






Maybe Victor has more on this.

Do you have an assumption as to how many years (or time period) orchids with pouches have been evolving.
How much time is represented in the genetics you are looking at?
Are there fossil records of orchids with pouches?

 

[Rick]

Do you have an assumption as to how many years (or time period) orchids with pouches have been evolving.
How much time is represented in the genetics you are looking at?
Are there fossil records of orchids with pouches?

I was trying to frame up a similar question, (so I hope I am not coopting or missrepresenting your question Lance).

Human DNA studies have used rates of mutation crossed referenced to the number of mutations in a loci to come up with some dates in human evolution. Has anything comparable done with slippers?

 

[Rick]

Fascinating! If you can compile some photos and even try to match them up with a Paph or two, that would be really neat to see.

Vic

This has been fascniating. I'm thinking of putting together a presentation for our orchid society. I'm going to need to do something better than the thumbnails of native bugs though.

 

[VAAlbert]

I was trying to frame up a similar question, (so I hope I am not coopting or missrepresenting your question Lance).

Human DNA studies have used rates of mutation crossed referenced to the number of mutations in a loci to come up with some dates in human evolution. Has anything comparable done with slippers?

Hi Rick et al.

Indeed, molecular 'dating' of the origins of plant groups has been attempted, and an estimate for the origin of Orchidaceae is ca. 50 million years ago. A better way of putting this is that the molecular phylogeny suggests that the divergence between the lily relative Astelia and Apostasia (Orchidaceae subfamily Apostasioideae; the 1st branch of the orchid family) occurred around that time.

The reference is:

Kåre Bremer
Early Cretaceous lineages of monocot flowering plants
PNAS 2000 97: 4707-4711; published online before print as 10.1073/pnas.080421597

On the same tree, monocot origins were estimated to have been early Cretaceous, at least 130 million years ago. Fossil angiosperms are known from around the same time. An undisputed monocot fossil dates back about 90 million years:

Gandolfo MA, Nixon KC, Crepet WL
Triuridaceae fossil flowers from the Upper Cretaceous of New Jersey
AMERICAN JOURNAL OF BOTANY 89 (12): 1940-1957 DEC 2002

There are no unequivocal orchid fossils that I know of. However, there are fossil euglossine bees in amber, and these are dated to 20-40 million years ago. The euglossines are the resin bees, the ones that pollintae Catasetiinae, etc. -->

Poinar G
Paleoeuglossa melissiflora gen. n., sp. n. (Euglossinae : Apidae), fossil orchid bees in Dominican amber
JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY 71 (1): 29-34 JAN 1998

No fossils of pouches or slipper orchids otherwise, but since the slippers are close to the bottom of the orchid family tree, one could expect them to be almost as old. Maybe about the same age as the orchids as a whole. My own attempts at molecularly dating the origins of the slippers were published here:

Albert, V. A. 1994. Cladistic relationships of the slipper orchids (Cypripedioideae: Orchidaceae) from congruent morphological and molecular data sets. Lindleyana 9: 115-132.

I calculated that the molecular divergence between Apostasia and Selenipedium was in the range of 49.3-69.0 million years ago. This is basically consistent with Bremer's estimate, above.

Furthermore, I calculated the time for the Selen/Cyp divergence to be ca. 15.3-21.4 million years ago. Then from Cyp and any given conduplicate-leaved genus (Paph, Phrag, Mex) --> 18.6-33.8 million years ago. Moreover, between:

Paph and Phrag --> 17.6-24.6 million years
Paph and Mex --> 16.4-23.0 million years
Paph delenatii and Paph glaucophyllum (or sukhakulii) --> 5.4-7.6 million years
Phrag schlimii (or lindenii) and Mex --> 7.7-10.8 million years
Phrag schlimii (or lindenii) and Mex --> Phrag lindleyanum --> 5.4-7.6 million years

So, if we believe these dates for the sake of argument, the slippers may have originated 50 million years ago or more, with all of the genera diversifying from one another by 18-33 million years ago. Furthermore, one can argue that Paphs and Phrags diversified within themselves around the same time in Earth history, some 10 million years or more after the conduplicate-leaved common ancestor evolved.

If you agree that one can infer from the slipper family tree that inflated pouches were the original (primitive) state for the Cypripedioideae (see my earlier posts), then that would mean inflated pouches could be somewhere around 50 million years old.

All best,

Vic

 

[kentuckiense]

I'd like to hear thoughts on my observations about P. bellatulum and P. concolor(and the other Brachys but to a lesser extent).

When I look at the above two species, I see a clutch of bird eggs. The spots, the petal/sepal shapes, and the prostrate/pendant/short inflorescences just really bring that image to mind. In addition, don't the Brachypetalums tend to grow on limestone cliffs or something of that nature? It would seem like such a place would be a popular place for birds to nest.

Anyway, the point is that bird nest are places that I would think a fly would love to visit. There would be fecal matter, possibly broken eggs, and even dead chicks. By mimicing a clutch of eggs, a bloom could attract the same flies that would be attracted the those eggs.

I know it's all simple speculation, but does anyone find this to be plausible at all? Have bellatulum/concolor pollination mechanisms been studied? Does anyone know what the eggs of the local birds look like?

 

[Braem]

Dear Victor,

lovely posting. But that is where I start having problems. Where is the tangible proof for all that. WHAT are you people looking at. WHICH part of the genome. WHY that part of the genome. etc. etc.

All I hear is: We have determined that ... we have calculated that ... etc. Were is your tangible proof that you really are hitting the right things?

Now to the bees. OK, I grant that we have bees that can be dated. But that means that we have bees that can be dated. Nothing more, nothing less. Its the old story about seing a person carrying a pencil. Does it mean that the person can write? NO! It only means that the person has a pensil and is capable of carrying it.
Because those bees NOWADAYS polinate certain orchids does not mean that they have pollinated certain orchids before.

We are running into a serious problem in this discussion. We should learn to walk first and then consider running.

Victor, in my opinion, there is no point in discussing results until we have discussed the materials amd methods. First we must do the "WHAT", the "HOW" and the "WHY" ... then we can talk about the results and more important about the INTERPRETATION of the results.

regards
Guido

Hi Rick et al.

Indeed, molecular 'dating' of the origins of plant groups has been attempted, and an estimate for the origin of Orchidaceae is ca. 50 million years ago. A better way of putting this is that the molecular phylogeny suggests that the divergence between the lily relative Astelia and Apostasia (Orchidaceae subfamily Apostasioideae; the 1st branch of the orchid family) occurred around that time.

The reference is:

Kåre Bremer
Early Cretaceous lineages of monocot flowering plants
PNAS 2000 97: 4707-4711; published online before print as 10.1073/pnas.080421597

On the same tree, monocot origins were estimated to have been early Cretaceous, at least 130 million years ago. Fossil angiosperms are known from around the same time. An undisputed monocot fossil dates back about 90 million years:

Gandolfo MA, Nixon KC, Crepet WL
Triuridaceae fossil flowers from the Upper Cretaceous of New Jersey
AMERICAN JOURNAL OF BOTANY 89 (12): 1940-1957 DEC 2002

There are no unequivocal orchid fossils that I know of. However, there are fossil euglossine bees in amber, and these are dated to 20-40 million years ago. The euglossines are the resin bees, the ones that pollintae Catasetiinae, etc. -->

Poinar G
Paleoeuglossa melissiflora gen. n., sp. n. (Euglossinae : Apidae), fossil orchid bees in Dominican amber
JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY 71 (1): 29-34 JAN 1998

No fossils of pouches or slipper orchids otherwise, but since the slippers are close to the bottom of the orchid family tree, one could expect them to be almost as old. Maybe about the same age as the orchids as a whole. My own attempts at molecularly dating the origins of the slippers were published here:

Albert, V. A. 1994. Cladistic relationships of the slipper orchids (Cypripedioideae: Orchidaceae) from congruent morphological and molecular data sets. Lindleyana 9: 115-132.

I calculated that the molecular divergence between Apostasia and Selenipedium was in the range of 49.3-69.0 million years ago. This is basically consistent with Bremer's estimate, above.

Furthermore, I calculated the time for the Selen/Cyp divergence to be ca. 15.3-21.4 million years ago. Then from Cyp and any given conduplicate-leaved genus (Paph, Phrag, Mex) --> 18.6-33.8 million years ago. Moreover, between:

Paph and Phrag --> 17.6-24.6 million years
Paph and Mex --> 16.4-23.0 million years
Paph delenatii and Paph glaucophyllum (or sukhakulii) --> 5.4-7.6 million years
Phrag schlimii (or lindenii) and Mex --> 7.7-10.8 million years
Phrag schlimii (or lindenii) and Mex --> Phrag lindleyanum --> 5.4-7.6 million years

So, if we believe these dates for the sake of argument, the slippers may have originated 50 million years ago or more, with all of the genera diversifying from one another by 18-33 million years ago. Furthermore, one can argue that Paphs and Phrags diversified within themselves around the same time in Earth history, some 10 million years or more after the conduplicate-leaved common ancestor evolved.

If you agree that one can infer from the slipper family tree that inflated pouches were the original (primitive) state for the Cypripedioideae (see my earlier posts), then that would mean inflated pouches could be somewhere around 50 million years old.

All best,

Vic

 

[Braem]

Evolution of Orchids

Folks,

this is from a recent article in the Orchid Review (Kotsybar, 2006).

"Orchid origins and adaptations: Some botanists say the degree to which orchid genera readily hybridise with one another indicates orchids are very recently evolved. They declare orchids must be very young in evolutionary terms as evidenced by the genetic compatibility of so many genera. Others insist the ubiquitous presence of orchids worldwide is best explained if orchid ancestors cam from Pangea - the ancient , single continent from which today's landmasses split, 225 million years ago. Mysteriously, the fossil record can validate neither theory. There simply are no confirmed fossilised orchids - not even seed or pollen microfossils. The prevailing theory that orchids split off from the modern lilies, which some resemble, has been staggered by recent DNA analyses, which designate asparagus as orchids' closest cousin."

Now that paragraph can easily be rephrased as follows:

"Orchid origins and adaptations: We don't have a clue. "

Now, this may change in the future, and I am happy to accept that molecular genetics may be the method of choice, but I would like to see a few facts. See my other post.

Guido