reason behind alkaloid content of plants

[teonanacatl]

has this been studied??? i know many people say that the reason lophs contain mesc is to deter predators because they eat it then trip and dont like it, or maybe its too bitter. but if this is the case why does t. peruvianus have it, its got huge violent spines to protect it. DMT in psychotria, isnt orally active so there is no benifit here. psilocybin, higher psilocybin:mushroom weight when young and so less potent when older, but still contains psilocybin so the idea that its there to protect the fruit untill its released its spores has flaws.

also the idea that these are produced as by products to get rid of excess nitrogen like we have urea doesnt make sense because then there would similar compounds in all plants. also older leaves would be packed with them as this is the only way i can think of plants excreting anything.

i believe that these alkaloids play a different role, mainly that they are there to store nitrogen and other minerals that can be easily realeased when needed. its been said that pachanois store mesc till winter then use it over winter. this means its using or excreting it in some way. if it shuts down and goes dormant then internal systems would take over and a store of nitrogen would come in handy. this is the same with dmt, concentraions are highest in the early morning and late after noon. this means it can store of make them at night then use them during the day. it doesnt however fit with psilocybe mushrooms though, it could infact be used to rid waste in them.

i would love to hear other peoples views on the subject and feel free to rip my theory to pieces with correct information.

[M S Smith]

Here are some snippets put together of a couple of different thoughts on the subject I had written in the past. I left out cactus evolution in relation to animal predation for simplicities sake.

~Michael~

There are many factors in regards to what supports the gradual evolution of a plant. A cactus is generally believed to have dropped its leaves due to the leaves causing greater transpiration, something that a desert plant found disadvantageous for survival (even tropical cacti are believed to have originally developed from hardened desert cacti). Therefore those plants with smaller leaves lost less water and therefore were able to survive better to pass on their genes. Then cacti with similar genes would again cross to create even smaller leaves until is all we have left in many cases is a spine, the remnant of the "leaf vein" (xylem and phloem tubes).

Now one can say also that cacti developed alkaloids by the same principle; that those plants who early on had the mutation of alkaloid production where able to survive the onslaught of bugs, animals, and fungus/molds better than their non-alkaloid containing relatives and therefore continued to interbreed and continue to increase alkaloids. But this makes little sense when one looks at cactus survival among species that don't carry any large degree of alkaloids. High alkaloid bearing plants can live right alongside low alkaloid bearing plants and suffer from similar outside agents, but it does not appear that the alkaloids necessarily prevent them from being attacked to any substantial degree less than their non-alkaloid bearing kin.

One must also consider the fact that not every feature of a plants evolution is necessarily for primary survival advantage. If the cactus that was developing smaller and smaller leaves through ages also had a gene in it that was producing significantly small amounts of alkaloids then the alkaloids are not the primary factor in evolution, but only a secondary factor as it was the plants survival due to small leaves that got it to its present point and not the alkaloids which simply increased due to the fact of being in the plant that was surviving due to lowered transpiration.

Another good example might be a plant that mutated in its flower and due to this mutation the flower became more attractive to pollinators and therefore was able to produce more seed to propagate the mutation. The mutation can continue to spread among the species, but what if along with the flower mutation there was also a mutation in an alkaloid producing gene. Though the flower is the main vector of its reason for advancing evolutionarily and surviving better the alkaloid gene gets to piggy-back upon the good fortune of the plant having produced a more attractive and easier pollinated flower.

What I really mean to say is that not every feature of a plant or animal, has evolved to the main benefit of the organism, particularly if another feature of it is of primary benefit in its evolutionary survival. Other genetic characteristics can get carried along. In some cases we can find that negative genetic traits can get passed on within a species if the more positive one benefits its survival. This is most prevalent in artificial crosses due to speed up time for full development, but such negative features seem to be pronounced much less in species that have evolved over millennia. (I could probably use modern dog breeding as an analogy, but I will spare everyone.)

In the end bugs and fungus/molds attack cacti with apparently little respect for alkaloid contents. And the likelihood is that these agents, with a much quicker generational cycle, would easily adapt (evolve) to any changes the cacti could produce over their longer generational cycles

Along with alkaloids as a defense mechanism I need to have more support for the evolution of spines as a defense mechanism as well. In my opinion spines are a product of the survival benefits of less transpiration while alkaloids are a byproduct of other primary evolutionary factors.

As for alkaloids playing a part in plant physiology I won’t disagree to any great degree, but there have been studies of some cacti that show no detectable alkaloids at all. But it certainly would appear that alkaloids are a predominant feature of Cactaceae, but again, and for many of the same reasons outlines above, their development of alkaloids probably has nothing to do with predators. Now of course the alkaloids would seem to be a more likely defense against smaller predators, such as insects and molds/fungus, but as we all know bugs and molds/fungus continue to attack even those plants that contain the highest levels of alkaloids. Alkaloids probably play a part in the internal regulatory features of cacti, but not as a defense mechanism.

[teonanacatl]

thats a interesting theory about the piggy back genes. is mescaline considered a trait evolved by cacti or a trait cacti evolved from. a good example is lophophora, which one came first??? my bet would be on diffusa which has then evolved by its self and evolved a very different chemical structure, williamsii i believe would remain very similar to its previous from as the populations can readily interbreed. but im sure ms smith can fill us in more about that.

the fact that not all plants contain alkaloids and that it would be expected that if they were used in storing products more would have them isnt nessesarily true, more new world plants contain them then old world plants yeah, this would point to them as a evolved feature. along way back if one line of plants developed this trait these days this could be evident in many families these days. evolution away from them could also occur. i like mssmiths theory which i will call the piggy back theory and i think this can be incorperated into the storage thoery.

things other then alkaloids could be used to store nutrients aswell and im sure that they could be found in almost every plant.

obviously mesc isnt made in the root but in the cells as a metabolite of photosynthisis. it could even be involved in photosynthisis which could be prooved by examining the percentage in the green layer under the skin, supposedly where all the mesc is anyway. mesc is obviously quite a stable molecule. unlike khats alkaloids (cathodine????) which are said to be destroyed by heat and light. in this case the plant could store minerals or even O2 or carbon which would be releases during the heat of the day which for both cacti and khat is extreme. i believe stoma close during the hottest parts of the day to conserve moisture. this also means CO2 and 02 induction is stopped so having molecules that are destroyed by heat would allow for stored CO2 and O2 that could be utilised during the day.

a study done on pachanoi cuttings from the same parent grown in the same conditions but with different soil pH's would give details on which groups of minerals are required for mescaline production. also long growing seasons where the plant doesnt go dormant could test the theory that mesc builds up untill winter and then the plant utilises the nutrients. if the plant used mesc as a storage facility then i suspect that once mescaline reached a certian level the plant would stop producing it or use it whilst producing it, could produce differnt growth. where as if its a waste product then it would keep being made and would reach toxic levels at which the plant would haveto exibit some symptoms.

now im sure many things here are incorrect and ive over looked somethings so someone please correct me.

[mescalito]

What's more interesting is that we have specific receptor sites for these chemicals that alter our consciousness and help us to connect with nature

[apothecary]

The common theory that alkaloids/thc/etc are for warding off animals is a bit unfounded imo.

If you think about it, no animal is gonna trip off a bite of cactus and then say "no more!". Lots of animals are recorded as being quite interested in hallucinogens.

Regardless, in my opinion active defense against attack from predators in plants is a one item list. Poison.

Things like bitter tasting flesh, and tough skin are passive defense mechanisms and it may just be, for example in Peyote that the "fittest" (re: survival of) ones where the bitterest ones, and the bitterness genes are closely linked to the ones that produce various alkaloids.

If alkaloid production was an active defense mechanism, it'd be a lot more present and "extrovert". e.g. the bufo toad, if you bite it, you're gonna trip for sure. The latex is everywhere, and you can easily see this is an active defense mechanism.

This of course doesn't explain alkaloids/thc/etc in plants that only have insect/invertebrae (slug, etc) predators, and no animals predators.

As such, I'm quite willing to accept a hybrid of Smiths and Macas theories.

[nabraxas]

yep

quote:

---

a hybrid of Smiths and Macas theories

---

why do poppies contain opium?

why does MJ produce THC?

i always leaned towards the idea that these things were there specifically for us to discover.

the really useful chems like asprin, opium & THC, were fairly easy.

basic psychedelics weren't hidden too well either, & their discovery may have started the whole "religeon" ball rolling.

seems the more interesting psychedelics, the PEA's had to wait a little while, but once we knew where & how to look.....

so, it seems to me that a whole pharmacopia has been integrated into the plant world & as our understanding increases drugs manifest which should improve our understanding further.

the fact that this hasn't happened, i blame on the commercial aspect ov research.

[Darklight]

I don't believe that plants do anything for one " reason ". That would be wasteful in energy and possibly unstable in evolutionary terms.

What you might be looking for is a set of causes that has either culminated or resulted in secondary metabolites as an outcome. The metabolites may have a direct use for the species or they may not, being waste products from a previously metabolically important path and are there in that form because they can be safely stored. Or it could even be a remnant process now irrelevant over time and not 'in use' but inherited from ancestors

Personally I'm thinking of DMT here, from experience but my work needs further research beyond the scope of this facility. I tried everything to get Acacia phlebophylla to proliferate in tissue culture, and over the years and dozens of subcultures all I got were increasingly stunted plants with no internodes, no roots and each sub resulted in smaller leaves than the one previously.

Then I reaslied DMT was on the IAA pathway. IAA is a naturally occurring auxin that stimulates- you guessed it- leaf size, root growth and internode length. I started adding things to the TC media working backwards down the path- l-tryptophan, something else ( can't recall ) and l-glutamine. And in one l-glutamine subculture we could go from internodal cuttings to quality rooted plantlets.

The fact is that phlebs grow on some pretty weird soil and rock in vivio. They may have needed something to help them get taller, send out strong roots, or dissolve some nutrients for use. DMT may or may not be good for keeping away insects, or it might be an end product with no use- or something inbetween

This is all conjecture mind. It would be possible to run experiements looking for DMT production in the non-glutamine media and comapring those plantlets with those grown in a glutamine media- but I'd need special guvvy permission, a few months spare and someone to wash the jars All it would prove was that DMT production exists as a necessary part of the plant's functioning in vitro, and maybe not even that

[teonanacatl]

quote:

---

Then I reaslied DMT was on the IAA pathway. IAA is a naturally occurring auxin that stimulates- you guessed it- leaf size, root growth and internode length.

---

i was thinking that last night aswell. which would be one reason they would store such complex structures, every step down would allow a different chemical to be used and then once broken down again it can again be used and so on. quite nifty really.

[t st tantra]

2 points

can you explain higher alkaloid levels in more mature plants?

its confusing when you include plants like mj and opium because they are the results of 1000's of years of selective breeding.

teo,your thinking parrallels my own.

t s t .

[devils_cactus]

once upon a time i spined and skinned a cactus then ate it piece by piece...common we've all been there

yuk...if i wasn't a determined human and say...a meer cat i would definently say..."heck no! fuck you cactus!!!"

[Happy Cadaver]

If alkaloids were produced to deter grazing animals, then they're doing a bad job as a certain group of humans are rapidly tracking down these specific alkaloid producing plants, propagating, harvesting and consuming them .

Maybe it's a survival mechanism. 'Humans like eating us, they'll protect us'. Very homocentric of course, we are the Centre of the Universe.

I wish we would be able to admit we don't know why If a plant was to juice up a human and extract the alkaloids out of it, what conclusion do you think the plant would come to as why we produce such chemicals? God, we don't even know why, we just are.

[apothecary]

tstantra, I included opium and mj because they are examples of plants that are psychoactive but not due to alkaloid content. If you don't think high THC content plants would be naturally occuring without selective breeding, then let me use another example.

Salvia Divinorum.

Higher levels of alkaloids can probably be explained simply by the fact that as the plant gets larger, it produces more byproducts of whatever naturally occuring proccesses create these alkaloids.

Just like a more mature plant is going to contain more moisture, fibre, and tougher skin, as will its alkaloid content by higher too.

Darcy, very interesting mental image there, cactus picks me up, stores me in a cupboard for 3-4 weeks, cracks open my skull and scoops the calcified pineal gland from my brain in an attempt to lick up the darkness induced DMT contained therein.

devils_cactus, I've never cut up and eaten a cactus. Only a few times have I cut a cactus, and that was to propagate it further, not hurt it.

[ 23. February 2005, 20:21: Message edited by: apothecary ]

[teonanacatl]

i went searching through some biochemistry books on secondary plant products today at uni and it seems many plants utilise the tryptophan, tryptamine pathway to store IAA. also the book had the pathway for mescaline production in the plant, will write it down and post it :D

the higher production of chems in older plants would depend on whether they used them for storage or disposal. photosynthisis, transperation, production of secondary chems and plant growth would all increase as the plant got older.

when i finish the books im reading now i might jump on this one and see how much i can digest before i fall asleep. currently got 2 weeks to read plants of the gods, soma the divine mushroom of immotality, wonderous mushroom, psilocybe mushrooms of the world, ethnobotany the study of a disapline, flesh of the gods and one on kava cultivars. anyway im pretty sure the research has been done and definetly doesnt point to alkaloids as defence mechanisms.

another example to disproove this, back when kratom was legal i found the easyest way to get catipillars off it and they loved it was to shake the plant cos they were all so stoned they would just fall off and lay on the grass lol.

[teonanacatl]

and what do you think would be stronger, a animals desire to eat or a humans desire to get high???

[Stonehenge]

Chemical production in plants is due first of all to mutations. Random mutations do occur throughout history in plants and animals. Those that confer an advantage, tend to be retained and those that don't are lost. When sugar was first produced by the first plant, it gave energy and the proto plant was successful and evolved into many species we see today. When a plant produces a chemical that is bitter, it puts off plant predators, as others have pointed out. This gives an advantage to the plant and the production of that chem is retained. Likewise, if a chem is produced that makes the animal dizzy, disorientated or sick, that animal is very unlikely to eat it again. Even if it doesn't deter all animals, if it gives more protection that it costs the plant in energy to produce it, that trait will likely be retained. Many animals do not produce mao's or didn't in the distant past. This can explain the production of dmt which also tastes bad.

Stoney

[delysid]

..I seem to recall on the tail end of a documentary on Wild Cats, some discussion about 'cleansing'

The question was : why do domesticated cats and dogs eat grass .. then vomit. Some examples were given.

Firstly, a variety of volcanic mud conting certain compounds was found to be 'used' by a large congregation of both pigs and small finch. At first glance it appeared the usual scene, pigs rolling in the mud, having way too much fun, with the birds frantically playing alongside them. Upon closer examination it seemed the pigs were 'eating' the mud, as were the finches. (the mud was quite light in colour, similar to clay) Now the reason given by the film-maker, was the calming, "antacid" effect of the mud, due to certain compunds (not mentioned). And both the finch and pig were 'using' the mud as a calmative to adjust their internal chemistry after a few weeks of feeding.

The second example moved swiftly to the large female cats .. lioness, leopard etc. Where the discussion regarding grass eating and purging came into focus. It appears that domestic cats and dogs do this as a body cleansing function. By eating the grass and adjusting stomach pH way out of normal levels, the animal can incite vomitting, which it does so casually.

The documentary then followed the path of a large cat into the jungle, where it was spied munching down on some of our old friend B.Caapi. It then lay there, on its back, the way so many domesticated cats do in front of a fire. The camera-man zoomed up on its eyes .. glassy .. biiiiig eyes .. with that all too familiar look to them. This was the first time I became aware that it is not only humans who know the secrets of plants.

It was a David Attenborough presentation .. I still recall his closing words : "What else about these hallucinatory realms does the Large Cat know.."

[delysid]

agreed that evolution is brought about through mutation , however disagree at it being 'random'.

obviously there are physical phenomena which drive evolution, which is why our eye sockets are depressed, protected, so as the eye is not damaged out on the end of some probuscus (a la snail)

modern science has its money on solar radiation as the great mutator. well founded too, nothing seems as potent a reactor than sunlight, inclusive of UVA and UVB emission and heat.

however it seems implausible that these alone can be the only mutanagenic forces.

plants and animals dont go about the place, randomly producing chemicals in desparate hope that they might force some evolutary change. The first mutanagenic force is the physical environ, including the sun. the resultant change internally might lead to the production of chemicals necessary for survival, but it is not a random event. Adrenalin comes to mind, as environmental change is measured by the animal, and awareness to danger increases, the onset of the fight or flight scenario builds, and adrenalin is released in large doses as an aid.

The events leading up to an environmental setting that calls for an evolutary change might be random.. but the resulatant chemistry is not random.

McKenna puts forth an argument for dietary influence as being the next greatest mutator in both plant and animal kingdom.

(which is why some species of fungi produces differring levels of (unwanted) strychnine and cyanide, dependant on the media in which it propagates. and why some animals, with an expanded food source, have greater ability for adaption and hardier constitution.)

..back to THC and the like being used as a retardant to attack. Unlikely, most of the time these compounds have a primary function, like being sticky to catch pollen or sweet smelling to attract pollenating bees, and that subsequently makes it pleasant/unleasant. Eucalyptus, mescaline, psilocybin, rubber, lavendar etc etc all have a primary function for metabolism, secondary to trying to ward off predators.

personally i believe psilcybin as the perfect metaboloid for the mushroom, what else would you choose to pump through that vast, intricate, delicate mycelial network, and wet-fleshed wooden trunk ? :D

2 cents

[Darklight]

teonanacatl:

i went searching through some biochemistry books on secondary plant products today at uni and it seems many plants utilise the tryptophan, tryptamine pathway to store IAA.

Yep a lot do, however this is the first time I have encountered any, incl quite a few other acacia species, which require supplementation along that pathway in order to maintain proper growth in vitro.

Not only that, it doesn't want to be spoon fed tryptophan in order to produce IAA, it wants to do it on its own- I had to go back down the path another two or three steps to glutamine before it started responding

[Hagakure]

delysid:

agreed that evolution is brought about through mutation , however disagree at it being 'random'.

obviously there are physical phenomena which drive evolution, which is why our eye sockets are depressed, protected, so as the eye is not damaged out on the end of some probuscus (a la snail)

modern science has its money on solar radiation as the great mutator. well founded too, nothing seems as potent a reactor than sunlight, inclusive of UVA and UVB emission and heat.

however it seems implausible that these alone can be the only mutanagenic forces.

plants and animals dont go about the place, randomly producing chemicals in desparate hope that they might force some evolutary change. The first mutanagenic force is the physical environ, including the sun. the resultant change internally might lead to the production of chemicals necessary for survival, but it is not a random event. Adrenalin comes to mind, as environmental change is measured by the animal, and awareness to danger increases, the onset of the fight or flight scenario builds, and adrenalin is released in large doses as an aid.

The events leading up to an environmental setting that calls for an evolutary change might be random.. but the resulatant chemistry is not random.

McKenna puts forth an argument for dietary influence as being the next greatest mutator in both plant and animal kingdom.

(which is why some species of fungi produces differring levels of (unwanted) strychnine and cyanide, dependant on the media in which it propagates. and why some animals, with an expanded food source, have greater ability for adaption and hardier constitution.)

i disagree with what you are saying but i just got back from a few beers and may be misunderstanding your later point.

mutations are completely random - from all we know you can not mutate in any direction. mutagens change dna randomly in ways like deletions, substitutions, frame shifting etc etc but all of these are random.

now what i think you are saying in the fifth paragraph when you liken the process to adrenalin is that mutations increase when the situation gets tough for the animal increasing diversity and increasing chances of survival. yeah?

this is false. mutations may be occurring all the time and are not affected in any way by increasing environmental pressures (unless of course those environmental pressures are increased mutagens).

it is the new selective pressure which gives importance to mutations which would otherwise be lost in the gene pool.

i will use a well tested and simple example to show what i mean. you could have a whole lot of brightly coloured small fish in an enclosed pool. the most brightly coloured will reproduce the most sucessfully and the offspring will get more and more colourful(more colourful = more sex = more babies).

introducing a predator species of fish however will change the situation and create a new selective pressure. these fish may have had a mutation which makes them a very pale colour or a mottled camoflage pattern. with the introduction of big hungry fish the colourful fish will be more obvious and easier to hunt therefore eaten first. these eaten fish wont be reproducing while the dull and mottled fish will.

it may appear that with pressure these small fish mutate to change and adapt to the situation. this is not so. what is happening is a shift in frequency of certain genotypes and therefore a different display of phenotypes.

okay on to your next part. i think what you are saying is that animals that are exposed to more mutagens are more likely to survive. animals that eat more mutagens adapt more. well this is a fair enough statement. but be aware that all of these mutations are random and selctive pressures are what does the seperating into a specialised organism that has its niche in the ecosystem.

i would assume that if you did an experiment with a series of organisms exposed to measurable quantities of mutagens you would get something of a bell curve in terms of adaptability. no mutagens at all (very hard to test - dna has correcting mechanisms but the odd errors get through without external mutagens present at all) would mean limited diversity in the population and less fitness when exposed to some kind of pressure. to many mutagens however will result in a whole lot of mutated fetuses which could very well die early and not live to spread genes.

so the right amount is needed.

btw modern science doesnt only have its money on ultra violet radiation. it is very much aware of mutagenic chemicals and has done a lot to document the different types of muttions caused by them (some cause bp substitutions others cause deletions etc etc)

i have listened to terrence mckenna's talks and from what i gather i think he is really just emphasising the importance of the change in diet of our caveman ancestors being responsible for more mutations. from what i gather (and i freely admit that i have not looked too deep into this specific matter) the current theories look at the increased evolution without factoring in more mutagens in the diet of these ancestors of ours.

bringing it back to the original question for why plants have these alkaloids i would agree with the piggyback genes etc but dont forget a few things which seem to be ignored.

bugs dont react like humans. attracted and repelled by different chemicals. in the desert, especially where biodiverstiy is limited and the numbers of plant predators a small group, i can very much seeing an on going battle between a specific bug and the cactus.

if the cactus with more mesc get eaten less - their offspring more likely to survive, then the bugs which are most tolerant to mesc more likely to survive so the bugs develop tolerance. and on and on the spiral goes.

i may have a poke around some journals later and see if the mesc theory of bug repellent is a theory or if they have shown it to be true.

unfortunately this is a topic i have a lot of interest in so i have put you all through a lot of reading. any questions on anything i say shout em out but more importantly crank out the corrections. not sure about a few details in there but the genetics stuff should be solid as a rock (i hope)

[t st tantra]

dont think we can assume the same mechanism for all these substances.

am curious about the uv flourescence of at least some of these substances.i think of dmt and mesc as being storage forms for future growth that may be activated by changes in uv levels[?].

t s t .

[Benzito]

As far as alkaloids deterring animals:

My rabbit once ate some of my morning glory vine, and tripped HARD for 3 days.

Sat in one place in the backyard, even when it was pissing down rain. Even though he normally runs around like a lunatic all day long.

He just sat there looking terrified the whole time.

However, he now tries to eat the MG at every chance he gets! He has had a few other cases of catatonia, and I can only interpret it as him tripping.

He has also just recently decided he likes wormwood. After a few months, in which he never touched it, he just went nuts and stripped a small plant in the space of two days!

So, he hasn't been deterred by alkaloids yet. And neither have I. :D

Just in-case your interested, the 'flying saucers' are his favourite MG. I've also got blue stars, and pearly gates but he's not as keen on them.

???

[Hagakure]

tst - yeah chances are they will have a variety of different reasons for their existence.

im curious if these UV levels would relate to the traditional special times for harvesting.

benzito - mammals seem to really like tripping. heard about rabbits, cats, deer, elephants, dogs and monkeys.

and come to think of it i think some beetles get hammered on some leaf that they consume - they just lie there in a coma like state, wake up, and go back for more. you would think natural selection would have taken these guys out already.

[Stonehenge]

Benzito, that is an interesting story but can you imagine an animal doing that in the wild? Any rabbit who sat in one place very long would be eaten. Hence, in the wild, the mg's defense mechanism works well. In a protected environment, other things happen.

Hagakure, you said it very well. Mutations are random and most of them are harmful to the organism, not beneficial. If even 1 in 10,000 gives an advantage, then that's the one that will be retained. Too many mutations will lead to extinction because the other 9,999 out of 10,000 are harmful. Mutagens are harmful in the short run but in the long run are neccessary.

Many plant medicines come about this way. If an alkaloid is produced that lowers blood pressure, any animal that eats it is likely to become dizzy or sick. Humans use it to treat conditions. Same with thc and many other things. Penicillin was developed by a fungus to kill other fungi and bacteria. It was a random mutation that resulted in the fungus' competitors dying off. With all the food to itself, the penicillin fungus thrived and the mutation was passed along.

Stoney

[M S Smith]

The Age of Mammals or the Cenozoic began about 65 million years ago (MYA) and conjointly with the decline of Dinosaurs. This is also the period in which the Cactaceae began, plants which evolved only within the New World. It would seem as though should cacti and mammals in particular evolved primarily from the same period we would have a larger degree of animals which would have evolved “primary” means of addressing the difficulty of eating spine and alkaloid bearing plants. But is seems clear that there are not any animals species which consider Cactaceae as their main food source, but rather most animals who eat cacti, the pads in particular since they are bearers of spines and alkaloids (and not the nectar, petals, fruit, or seed), have evolved with other primary food sources in mind.

If animal evolution didn’t adapt over time to the changes developing in the Cactaceae, and the animals which eat cacti today rely on other primary food source, then it seems unlikely that spines and alkaloids developed to ward of animal species, who as co-evolutionary creatures would have adapted if the necessity on cactus as a food source existed. Animals continue to eat cacti, in particular the Opuntieae Tribe, without deference to not having features specifically designed for such purposes. But it may be that the spines, which I support as evolving to limit transpiration, prevented co-evolutionary tracks if during this period of possible adaption the animals were able to look to other food sources.

Opuntiofagous vertebrates include:

Berlandier’s Tortoise

Galapagos Tortoise

Galapagos Iguana (two species)

Galapagos Dove

Galapagos Mockingbird

Genovesa Cactus Finch

Daphne Major Cactus Finch

Shasta Ground Sloth

Desert Cottontail

Nuttall’s Cottontail

Antelope Jackrabbit

Black-tailed Jackrabbit

White-tailed Jackrabbit

Spotted Ground Squirrel

Mountain Pocket Gopher

Banner-tailed Kangaroo Rat

Hispid Cotton Rat

White-throated Packrat

Desert Packrat

American Black Bear

Feral Burro

Wild Boar

Collared Peccary

Camel

Mule Deer

White-tailed Deer

Pronghorn

Bighorn Sheep

Steenbok (Bovidae)

Feral Goat

Uses of Opuntia ficus-indica as fodder for domesticated animals.

Source:

Cacti:Biology and Uses

Edited by Park S. Noble

University of California Press, 2002

Interestingly enough some 20 or so species of the Genus Opuntia (of some 180 species) that have been examined show alkaloids. Many of the tests didn’t even examine pads, but rather just fruit. The large presence of alkaloids in Opuntia species in particular, including some half dozen which contain mescaline, hasn’t seemed to bear much on whether the species are avoided by mammals.

I am not aware of the two other Tribes, Pereskieae and Cacteae, being the diets of anywhere near the amount that eat the flesh of Opuntieae, but would love to hear from others about it if they know something I don’t. Certainly many other non-Opuntieae Cactaceae bear alkaloids but it wouldn’t seem as though they are not eaten due to spines or alkaloids, features which haven’t prevented the ingestion of Opuntieae, but rather due to the prevalence of and thickness of spination which appears to have more to do with factors beyond animal predation. Small rodents have also been known to go after such large alkaloid bearers as the spineless Lophophora and Ariocarpus, but do not appear to be primarly food sources, but rather scavenged on and past over. This is at present likely due to the alkaloids, but only from creatures that hadn’t co-evolved with the alkaloids, but rather subsisted on other food and are put off by the alkaloids. But this certainly says nothing to support the evolution of alkaloids to prevent such eating.

I’ve rambled enough. I’m no authority so please be critical.

~Michael

[ 25. February 2005, 11:22: Message edited by: M S Smith ]

[teonanacatl]

i agree that mutations occur in the natural world all the time and thats why genetic diversity is so important, but as to plants developing chemicals overtime to deter animals that at the same time are also evolving at in some cases a quicker rate, every time the plant got bitterer then animals would be used to it. as we are also organic organisms we also share the use of alkaloids in our bodies to store and regulate chemicals. just because a plant produces a deadly toxin doesnt mean that it ment to and nor does it mean that its not evolving away from it.

its likely plants have enzymes to make these molecules and so its probably not hard for them, equilibrium would keep things going nicely. i believe we have reached a good conclusion and i will try to sum it up nicely but will probably fail.

the production of secondary plant metabolites to form structures capable of storing important organic compounds for later use or excretion of excess material is a evolutionary trait that follows the theory of natural selection. such metabolites can be caused by mutation occuring to the specific cells that are responsible for the creation of them and/or through the mutation of other cells that indirectly influence the creation of these organic compounds. mutations are completly random and may or may not be usefull to the plants survival. plants may produce organic compounds that serve more then one purpose, eg tastes bad and stores Auxins. however plants and animals that live together will evolve together and symbiosis or immunity between the two could eventuate.

now we just need to find out how to increase yeilds in our friends.