(Arboricultural-styled) 'Fact of the Day'

[Kveldssanger]

It's actually rather unfair to have biologists say that, as when explaining something one has to almost describe it in a human sort of way whilst still suggesting that plants are not like humans. That is what this author of the book I am reading stresses, and which is why I use certain words with inverted commas around them.

 

That comment by the biologist is rather nitpicky, as I think we all know they don't behave like mammals. There is nonetheless a large degree of similarity, though disparity presents itself as mammals and birds respond mainly to visuals / light, whilst insects and plants respond to chemicals primarily.

 

It seems almost pointless to try to not describe plants as if they were comparable to humans purely in order to teach, as one cannot teach the situation with ease to students and readers if they lack the entire basis (of which we don't even fully understand!) of how a plant functions within its paradigm.

 

I say biologists (and botanists) should focus on more important stuff than that. Pointing stuff out for the sake of pointing it out, when everyone knows it anyway, is a waste of time.

[Kveldssanger]

27/09/15. Fact #44.

 

Upon browsing (herbivory) of a plant (by insects, mammals, avifauna, etc), there is the potential for various direct responses from the plant. Many responses are considered to be under the banner of induced resistance, where physiological and chemical changes within the plant structure cause herbivores to be less attracted to further browsing, or cause herbivores to perform less favourably following further consumption.

 

However, the response may not always be beneficial for the plant in terms of resisting further herbivory. Induced susceptibility can and does occur, by where further browsing by herbivores improves their performance.

 

Other induced responses may be of no relevance to the plant-herbivore relationship. The healing of wounds, for example, is an induced response that has no direct impact upon herbivore performance.

 

It is also important to note that induced resistance is coming from the angle of the herbivore, and not the plant. Therefore, induced resistance may not benefit the plant - it only makes it harder for the herbivore. Induced defence, on the other hand, may improve plant fitness where there is risk of further herbivory - the plant may only improve its defence following a triggering event, because it is otherwise an inefficient use of resources to invest in such increased defence levels (where increased defence is not needed).

 

Further, where a plant consistently is faced with high levels of herbivory, induced responses may be permanently expressed to match the level of risk - and of course the opposite where there is low risk.

 

Sources:

 

Karban, R. (2015) Plant Sensing & Communication. USA: The University of Chicago Press.

 

Karban, R. & Myers, J. (1989) Induced plant responses to herbivory. Annual Review of Ecology and Systematics. 20. p331-348.

 

Nykänen, H., & Koricheva, J. (2004). Damage‐induced changes in woody plants and their effects on insect herbivore performance: a meta‐analysis. Oikos. 104 (2). p247-268.

Edited September 27, 2015 by Kveldssanger

[Kveldssanger]

Building on the above post, I think the following sums up the wonders of the plant world.

 

"Brassica nigra plants responded to incidental cues of moving snails (mucus) and became less palatable to snails before they were actually attacked; presumably mucus was a reliable predictor of increased risk."

 

So this begs the question...

 

...for this evolutionary trait to have come into existence, there must have been a time where the cabbage plant did not know what snails and mucus even were - nor could it even 'sense' it (mucus). It would have of course 'recognised' it was being defoliated, though if at one point it did not qualify mucus as an indicator of risk (because snails had only just realised how delicious and nutritious raw cabbage was!), it would not have receptors to identify that mucus was on its structure. How did it first begin to create receptors for identifying mucus as a means of predicting future herbivory, if it was not able to sense mucus at one point before (as it was not an indicator of risk)?

 

I do hope that made sense.

[Paul Cleaver]

Building on the above post, I think the following sums up the wonders of the plant world.

 

"Brassica nigra plants responded to incidental cues of moving snails (mucus) and became less palatable to snails before they were actually attacked; presumably mucus was a reliable predictor of increased risk."

 

So this begs the question...

 

...for this evolutionary trait to have come into existence, there must have been a time where the cabbage plant did not know what snails and mucus even were - nor could it even 'sense' it (mucus). It would have of course 'recognised' it was being defoliated, though if at one point it did not qualify mucus as an indicator of risk (because snails had only just realised how delicious and nutritious raw cabbage was!), it would not have receptors to identify that mucus was on its structure. How did it first begin to create receptors for identifying mucus as a means of predicting future herbivory, if it was not able to sense mucus at one point before (as it was not an indicator of risk)?

 

I do hope that made sense.

 

a chance mutation ?

[Kveldssanger]

It'd be a cracking coincidence if so. What would drive the chance mutation? The odds would surely be very low, with regards to receptors being developed within the leaf that identify the exact elements (and their mix within the mucus, all whilst excluding 'background' depositions on the leaf from other insects or environmental conditions) of mucus.

 

From reading this book I am building up a picture of an absurdly acute 'intelligence system' (not in the human sense of the word) within every plant.

[Paul Cleaver]

It'd be a cracking coincidence if so. What would drive the chance mutation? The odds would surely be very low, with regards to receptors being developed within the leaf that identify the exact elements (and their mix within the mucus, all whilst excluding 'background' depositions on the leaf from other insects or environmental conditions) of mucus.

 

From reading this book I am building up a picture of an absurdly acute 'intelligence system' (not in the human sense of the word) within every plant.

 

something happened genetically that made one plant slightly less edible than the other plants. The genes were passed on through seeds and several or several hundred mutations later over millions of years you get todays version. Just my thoughts.

[Kveldssanger]

Indeed, it would be on the genetic level. Perhaps the 'upregulation' (as I explained a few days back) of genes associated with response to herbivory, on one specimen, brought about the synthesis of adequate receptors to identify mucus and then have the plant respond to this receptor's signal by making themselves less palatable (but only to snails?).

[Paul Cleaver]

What would drive the chance mutation?

 

I don't know if its "driven" as such - any experts out there !

[Paul Cleaver]

Indeed, it would be on the genetic level. Perhaps the 'upregulation' (as I explained a few days back) of genes associated with response to herbivory, on one specimen, brought about the synthesis of adequate receptors to identify mucus and then have the plant respond to this receptor's signal by making themselves less palatable (but only to snails?).

 

I see your point and its fascinating but at some point before the "intelligence" it must have made an evolutionary leap of chance?

[Kveldssanger]

But how many sides to the dice of evolutionary chance are there?

 

I'm not nit-picking on purpose, I'm just awe struck by the sheer brilliance of the (chaotic?) system.

 

Ordo ab chao? How deep does the rabbit hole go?