Quest for mold-resistant strains, Hawaii outdoor greenhouse grow

I think most people who use cannabis buy some weed from somebody, and don't know whether it's indica or sativa, let alone the name of the strain. Most people don't know that what's called a sativa today is actually a hybrid of original sativa and indica. And then a very, very few people think about the origins of the cannabis species.

Although I have fun dissecting the science from my non-biological-science background, I actually don't have the knowledge or experience to know how plausible are the conclusions they're arriving at for the ancient origins. In other words, they could be making gross assumptions or flat-out mistakes, although that is probably much less likely if the studies are peer reviewed.

That said, there are definitely pollen grains of truth in all of it. 🤓
 
@Fenderbender said, "Indica & Sativa diverged a million years ago."
Coming back now to what Fenderbender said...

It may be true... way back in 2010, McPartland and Guy did a "molecular clock" type test on cannabis DNA...

"They estimated that Humulus and Cannabis diverged from a common ancestor 27.8  mya. C. sativa and Cannabis indica diverged 1.05 million years ago, but this was not published because the taxa differ at only one nucleotide site." [ source ]​

But notice that last bit... "the taxa differ at only one nucleotide site." I think that means one base pair in the DNA of the genome, of which there are over 800 million base pairs. Well, that surely isn't showing a distinction between sativa and indica biotypes.

This lead me to another study, published by the University of Toronto in 2018, which found evidence in the DNA related to the difference between THC-producing cannabis and CBD-producing cannabis, as a result of gene duplication and invading viruses...

"The enzymes making THC and CBD are encoded by THCA and CBDA synthase genes, respectively. Both are found on chromosome 6 of the ten chromosomes the cannabis genome is packaged into.​
• • •​
The gene sequences for the THCA and CBDA synthases are nearly identical supporting the idea that they come from the same gene which was duplicated millions of years ago. Over time, one or both gene copies became scrambled by invading [viruses], and by evolving separately, they eventually came to produce two different enzymes -- CBDA synthase found in hemp (fibre-type), and THCA synthase in drug-type (marijuana)."​
[ Review | Study ]​

I believe this can be viewed as an ancient (pre-human) emergence of the THC-producing biotype from the CBD-producing biotype.

Let's suppose for the moment that the divergence of sativa and indica did happen about 1 million years ago, and that viral attack coupled with evolutionary adaptation gave rise to THC production. What was also happening 1 million years ago?

The ice age of the Pleistocene Era started 1.6 million years ago, so 1 million years ago is about one third of the way into the ice age.

From an article by Sensi Seeds, 2020, titled "The Evolution of Cannabis Sativa & the Cannabis Ancestor":

"[during the ice age]...vast swathes of the planet iced over. Continental glaciers (vast ice sheets that cover entire land masses all the way to sea level) stretched as far as 40 degrees latitude from the poles, and thousands of plant and animal species went extinct, or were pushed into “refuges” that provided favourable enough conditions for survival.​
• • •​
The Cannabis genus was lucky enough to survive, and it is thought that it did so by occupying various refuges in Central and Southern Asia. There is little doubt among scientists that this period would have seen some of the most dramatic evolutionary change within the genus, as it rushed to produce genotypes that would survive in a radically different set of habitats. It is thought that the adaptations that led to the development of “sativa”, “indica” and “ruderalis” biotypes is likely to have occurred during this time.​
It is also believed that during this time, the cannabis plant gained the ability to produce THC, due to a mutation in the cannabinoid synthase gene. Thus, by the time cannabis began to split off into the types that we know today, it already had the ability to produce THC. The evolutionary pressures acting on it since then, both human and environmental, have influenced how much THC the various populations produce."​

Now let's think back again to the Oligocene cannabis of 28 mya in the subtropical environment of what would become the Tibetan Plateau, which split from humulus (hops) around that time, and may have resembled Humulus japonicus with its cannabis-like leaves. And remember, the plateau rose for a period of 5 million years, which may have gradually caused the natural selection of THC production and the emergence of the indica biotype. That would have happened between 28 and 23 million years ago. (Since 23 mya is the beginning of the Miocene Period, we could call this adapted biotype, Miocene cannabis.)

So which is it... sativa and indica split around 1 million years ago, or they split between 28 and 23 million years ago?

Could the Oligocene cannabis have survived and evolved as the Tibetan Plateau rose to its present-day elevation?

I wrote earlier in this thread: "...The possible epicenter of cannabis ("center of origin"), eastern Tibetan Plateau, near Qinghai Lake, elevation 10,500 ft., according to the 2019 study by McPartland, Hegman, and Long."

According to Sharma (1977), cannabis grows up to 10,000 ft in the Himalayas, and apparently its THC potency tends to increase with elevation.

So, yes... the Oligocene cannabis of the Tibetan Plateau may have evolved into the Miocene cannabis.

EDIT: If only it were possible to do a DNA analysis of Oligocene cannabis vs. the Miocene cannabis!

:ciao:
 
the Oligocene cannabis of 28 mya in the subtropical environment of what would become the Tibetan Plateau,
I did some reading about the climate of Tibet in the Oligocene.
Eastern Tibet does seem to have been a wet, tropical environment during the Eocene-Oligocene transition (~33 mya), but central Tibet seems to have had an arid environment as far back as 26 mya.
Copied and pasted:
The time at which the Tibetan Plateau rose to its present high elevation remains controversial, with estimates ranging from 40 Ma to more recent than 7 Ma. New stable isotope analyses of modern and accurately dated ancient paleosol carbonate in the Nima basin of central Tibet point to an arid climate and high paleoelevation (4.5–5 km, comparable to today's setting) by 26 Ma. Oxygen isotope values of ancient (26 Ma) soil carbonate are both very negative and indistinguishable–after modest corrections for changes in global climate–from the lowest (least evaporated) oxygen isotope values of modern soil carbonates in the area.
Source


This paper seems to agree with that too, but is focussed more on South East Tibet.
 
I did some reading about the climate of Tibet in the Oligocene.
Eastern Tibet does seem to have been a wet, tropical environment during the Eocene-Oligocene transition (~33 mya), but central Tibet seems to have had an arid environment as far back as 26 mya.
Copied and pasted:
The time at which the Tibetan Plateau rose to its present high elevation remains controversial, with estimates ranging from 40 Ma to more recent than 7 Ma. New stable isotope analyses of modern and accurately dated ancient paleosol carbonate in the Nima basin of central Tibet point to an arid climate and high paleoelevation (4.5–5 km, comparable to today's setting) by 26 Ma. Oxygen isotope values of ancient (26 Ma) soil carbonate are both very negative and indistinguishable–after modest corrections for changes in global climate–from the lowest (least evaporated) oxygen isotope values of modern soil carbonates in the area.
Source


This paper seems to agree with that too, but is focussed more on South East Tibet.

OK, so the first paper you mentioned is from 2007. The paper I referred to is this one from 2020/2021, which makes these conclusions which I think generally apply to the whole Tibetan Plateau...
  • The geology and climate of the region came together during the Mesozoic era, 252-66 mya
  • The landscape was comprised of mountains and deep valleys
  • The deep valleys contained subtropical plants and animals
  • The area "did not rise as a pre-formed plateau... driven solely by the India–Eurasia collision"
  • "The Tibetan Plateau did not form until the Neogene", 23 mya to 2.58 mya
I drew this conclusion... So, at 28 mya the valleys were likely still subtropical, and began "drying out" over the period of the next 5 million years. And by 23 mya, the high-elevation, cold, dry plateau was formed.

Here's that post again:


EDIT: By the way, I asked... "There's lots of wild cannabis growing in Central Asia, but I wonder if any strains have been identified that haven't been contaminated with cultivated cannabis."

The Real Seed Company says, "...it’s unlikely there are any pristine populations of truly wild Cannabis".
 
Sorry, I guess I wasn't being clear. What I was trying to say is that the arid, high altitude ecosystem was also present at that time.
In fact, given that the study you posted is stating that the humid subtropical climate is present at the bottom of deep valleys, there have to be mountainous landscapes surrounding them. The study you posted also states that there were temperate climate regions there, as well as the subtropical valley floors.
Both the studies you posted, and the ones I found agree that the formation of the plateau was over a very long period of time, and elevations of 4000m+ have existed in that region from before the start of the Oligocene.
Pollen assays can point to the presence of a plant in a general area, but the diverse environment within that area clouds what region the cannabis actually evolved in, and when it filled any specific environmental niche.

I hope I'm not coming off as argumentative, I really like debating stuff like this, and having ones ideas challenged can lead to more confidence in conclusions.
 
Sorry, I guess I wasn't being clear. What I was trying to say is that the arid, high altitude ecosystem was also present at that time.
In fact, given that the study you posted is stating that the humid subtropical climate is present at the bottom of deep valleys, there have to be mountainous landscapes surrounding them. The study you posted also states that there were temperate climate regions there, as well as the subtropical valley floors.
Agreed.
Both the studies you posted, and the ones I found agree that the formation of the plateau was over a very long period of time, and elevations of 4000m+ have existed in that region from before the start of the Oligocene.
Agreed.
Pollen assays can point to the presence of a plant in a general area, but the diverse environment within that area clouds what region the cannabis actually evolved in, and when it filled any specific environmental niche.
Oh yeah, clouded indeed! Well, the technique they used to differentiate cannabis from humulus involved looking at the spatial pollen groupings ("assemblages"). From the McPartland (2019) study's abstract:

"To dissect these aggregate data, we used ecological proxies. C–H* pollen in a steppe assemblage (with Poaceae, Artemisia, Chenopodiaceae) was identified as wild-type Cannabis. C–H pollen in a forest assemblage (Alnus, Salix, Quercus, Robinia, Juglans) was identified as Humulus. C–H pollen curves that upsurged alongside crop pollen were identified as cultivated hemp. Subfossil seeds (fruits) at archaeological sites also served as evidence of cultivation. All sites were mapped using geographic information system software. The oldest C–H pollen consistent with Cannabis dated to 19.6 [mya], in northwestern northeast China. However, Cannabis and Humulus diverged 27.8 Ma, estimated by a molecular clock analysis. We bridged the temporal gap between the divergence date and the oldest pollen by mapping the earliest appearance of Artemisia. These data converge on the northeastern Tibetan Plateau, which we deduce as the Cannabis centre of origin, in the general vicinity of Qinghai Lake. This co-localizes with the first steppe community that evolved in Asia." (*C–H = Cannabis or Humulus)

EDIT: It appears the authors made an error. The oldest C-H pollen (actually humulus) was located in northeast China, about 330 miles east of Qinghai Lake, not "northwestern China".

I actually didn't catch this before, so thanks for bringing the focus here. The whole theory presented by the paper, arriving at the very specific center of origin, is dependent on the logical analysis summarized in the above excerpt. And it all boils down to this sentence: "We bridged the temporal gap between the divergence date and the oldest pollen by mapping the earliest appearance of Artemisia." There could be a problem here... let's see if I can break it down...
  1. They associate wild cannabis as part of a steppe community (semi-arid, warm/hot summer, cold winter)
  2. They date the oldest cannabis-or-humulus pollen to 19.6 mya (fossil pollen study, northeast China)
  3. They date the divergence of cannabis from humulus at 27.8 mya (DNA molecular clock test)
  4. They consider the earliest appearance of Artemisia (fossil pollen study)
First, the whole center-of-origin theory comes into existence, in the area of the northeast Tibetan Plateau, because of (2)—fossil pollen study, northeast China.

EDIT: The study that's referenced for the date, 19.6 mya, actually identifies the fossil pollen as humulus, and not "indeterminant C/H". (study PDF)

The thing that jumps out at me is, they are strongly associating the presence of Artemisia (pollen) with the presence of wild cannabis. Without this, they don't have a theory. In fact, if any of 1-4 are in fact incorrect, they don't have a theory. If the whole method of using "ecological proxies" to differentiate cannabis and humulus is unreliable, they don't have a theory.

But for the moment, let's assume that 1-4 are correct. Does the logical analysis hold up? They are bridging a "date" gap and coming up with a geographic center of origin...

(A) C-H pollen 19.6 mya (B) oldest Artemisia pollen ? mya (C) C/H divergence 27.8 mya (D) center of origin 27.8 mya

In this "equation", (B) is the critical element. Yes, they are drawing on data that shows Artemisia and Cannabis co-exist in steppe-type environments (arid, semi-arid). And yes, they are drawing on data that associates arid/semi-arid environments with Artemisia, and arriving at locating these arid/semi-arid environments in the region of the northeast Tibetan Plateau...

"...we deduced the location of Cannabis during the temporal “missing link” between its divergence date (27.8 [mya])​
and oldest pollen (19.6 [mya]), using two sets of indirect data. Bosboom et al. (2011) mapped an aridification zone arising at the Eocene–Oligocene boundary. The periphery of their zone is demarcated by the central Tarim Basin, southern Mongolia, and southeast of the Xining Basin. A best approximation of this palaeogeographic zone was transferred to a modern map in Fig. 4. The oldest C–H pollen consistent with Cannabis (site #1) is located at the south-eastern perimeter of the aridification zone (Fig. 4)."​

Bosboom (2011) says, a "...significant aridification step occurs at ~36.6 [mya] as recorded by regional sedimentary records of the Xining Basin along the northeastern Tibetan Plateau...".

So, hold on here! The location of the aridification zone might be in the right place, but McPartland's center of origin occurs at 28 mya, not 36 mya—that's a difference of 8 million years! A lot can happen in 8 million years. It is theorized that the Tibetan Plateau itself rose up over a period of 5 million years. Fast forward 8 million years from 36 mya, and we can consult the 2020/2021 paper I mentioned before (Spicer, et al) that discusses the climate on the Tibetan Plateau around the period of 28 mya to 23 mya (i.e. mountains and deep valleys).

At this point in the deep dive, as things are becoming quite convoluted, I'm inclined to pull back a bit and rely on some of my own knowledge...

I am very familiar with Artemisia in a subtropical environment, growing in the foothills in California. This was in an area with very mild year-round climate, and also semi-arid. Lots of Artemisia grew around the perennial creeks—I recall a couple of species. This is definitely a place where cannabis could have also grown, and hops as well. This type of environment is in potential conflict with McPartland's north China assessment of Artemisia, Humulus, and Cannabis, where he places cannabis with artemisia, and humulus with forest species. At any rate, perhaps we could say there is potential compatibility if we consider that a subtropical environment in northeast China, as described by Spicer et al, has a less arid range (valley floor) and a more arid range (foothills). And I don't see a compelling reason to consider the very arid/colder range (mountain). I see also that artemisia, humulus, and cannabis would favor a riverside or creekside environment (riparian zone) in a semi-arid climate, and there could be trees all around in such a zone.

So, I'm starting to feel that McPartland's "ecological proxies" are off, which would imply that differentiating the morphologically-identical cannabis and humulus pollen is, basically, impossible. I could be wrong.

Let's look at the logical analysis again...

(A) C-H pollen 19.6 mya
[northeast China] (B) oldest Artemisia pollen ? mya (C) C/H divergence 27.8 mya (D) center of origin 27.8 mya [northeast China]

So, (A) is solid if we consider that it's either cannabis or humulus, 19.6 mya, but we don't know for sure which. (B) is solid because artemisia pollen is unique (although I'm not sure of the time period), and artemisia, humulus, and cannabis could all occur in the same assemblage. (C) is solid as long as molecular clock DNA testing is reliable. (D) may still be plausible, given that the geographic position of (A) is about 330 miles east of the proposed center of origin, Qinghai Lake.

The thing that stands out for me now is, there's nothing definitive pointing to the entire area of what is now China as being the center general area of the origin of cannabis. I mean, there's no fossil record. We do have divergence of cannabis and humulus at 27.8 mya. And we do have humulus japonicus (wild hop) being native to China, and its leaf structure looking very similar to that of cannabis. So we can infer that maybe the fossil pollen of the ancient ancestor of this species, or even the ancient ancestor of cannabis, is what has been found in northeast China (19.6 mya), and perhaps exists in other places in China as well. And we have the temporal association of cannabis and humulus—i.e. when the divergence occurred, both species would tend to inhabit the same biomes. And we have a theory that the Tibetan Plateau at 28 mya was comprised of mountains and deep valleys that were subtropical/humid or subtropical/semi-arid and could have supported both cannabis and humulus.

McPartland's theory is perhaps challenged by the fact that the hard evidence (fossil pollen) only goes back to 19.6 mya, while the point of divergence from humulus is 27.8 mya—that's (another) difference of about 8 million years! A lot can happen in 8 million years. I mean, what if cannabis diverged from humulus somewhere distant from northeast China, and then dispersed to northeast China at some point during the 8 million years? And at 8 million years, I would think the temporal association (i.e. co-habitation of biomes) would be perhaps less likely, or less of a "signal" as they say. I don't know.

At this point, I'm more-or-less content to accept that the origin of cannabis may be about 28 million years ago, and it may have originated somewhere in northern China. ...until someone can convince me that there's convincing data on a more specific center of origin.


I hope I'm not coming off as argumentative, I really like debating stuff like this, and having ones ideas challenged can lead to more confidence in conclusions.
All good... thanks for your input!

:ciao:
 
Today in the veg house... foreground is Humboldt Dream, background is taller Blueberry, and to the right is HI-BISCUS. All clones, all in 10 gal. pots. Next to move to flower house is the Blueberry, then the Humboldt Dream—I have clones of both. I'm trying to stagger the flips now by 2 weeks. The HI-BISCUS will need to be re-cloned.
veg_house.jpg


Meanwhile in the flower house... White Widow clone in 10 gal., recently moved from veg. She was root bound before up-potting, so somewhat stunted.
flower_house.jpg


:ciao:
 
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