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Henry J



Posts: 4565
Joined: Mar. 2005

(Permalink) Posted: June 15 2007,23:46   

Plants recognize their siblings, biologists discover
Quote
The next time you venture into your garden armed with plants, consider who you place next to whom. It turns out that the docile garden plant isn't as passive as widely assumed, at least not with strangers.

The botanical theory of relativity?

Henry

  
Ichthyic



Posts: 3325
Joined: May 2006

(Permalink) Posted: June 16 2007,00:17   

neat!

I knew lots of examples of allelopathic chemicals in plants, that work to reduce the growth, or just plain kill, non conspecifics, but surprisingly had never heard anything about kin selection in plants before.

unfortunately, I don't understand why the paper chose to twist the story and focus on this quote from Dudley:

 
Quote
Gardeners have known for a long time that some pairs of species get along better than others, and scientists are starting to catch up with why that happens,"


scientists have known for decades why THAT happens.

that plants can recognize KIN is an entirely different animal (pardon the pun).

My guess is that the story writers thought it more entertaining to write it like that for their "readers", and thought the whole "dinner party" analogy was somehow clever.

anywho, the point is it very much surpises me that such a simple experiment looking at Kin Selection in plants had never been tried before.

one of those "Doh!" moments, when you slap yourself in the head and say:

Why didn't I think of that?

I'll go farther than the article does and predict that as more studies are conducted, we will find that Kin selection is more common in plants with small scale seed distribution mechanisms.

IOW, plants that drop few large seeds, or don't have a lot of distance between parent and seedlings, will tend to exhibit this behavior more often than plants that rely on wind for seed distribution of many small seeds.

pretty basic prediction, really.  the less competition likely between parent and offspring, the less likely to develop a need for recognizing kin.

seriously, this is shocking to me that this is the first mention of kin selection in plants.

are there any botanists hanging around these parts that might shed a clearer light on this?

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"And the sea will grant each man new hope..."

-CC

  
nuytsia



Posts: 131
Joined: June 2006

(Permalink) Posted: June 16 2007,07:16   

Hmmm... interesting questions.

Seeds actually have a number of ways of trying to avoid germinating if established plants are already present.

Seeds are sensitive to nitrate levels in the surrounding medium. Where established plant are growing soil nitrate levels tend to be low. If levels are high it's suggest a low competition.
Similarly soil temperate fluctuations are used as a measure of competition. In an established environment the soil is insulated somewhat from the suns radiation during the day and losing heat during the night.
In bare/cleared areas diurnal soil levels can fluctaute wildly and again many seeds will repsond to that.
I have to do a lot of wild seed germination in my job and use of trace levels of KNO3 and comparison of constant and alternating incubator tests are a standard starting point.

---

The plant used in this work (Cakile) is an interesting member of the Brassicaceae, fruitwise, and from what I've observed probably exhibits two forms of dispersal.

(I've actually got a Cakile species under germination trial at the moment and it shows little in the way of dormancy. As soon as you extract the seeds from the fruits they tend to go - and quickly.)

The majority of the family have the typical dehiscent capsule that many might be familiar with, termed a siliqua (silicula applies to a minor shape change).

With Cakile the fruit is indehiscent and corky, usually holding a pair of seeds. The fruit actually splits into two pieces. The larger top half (normally holding a larger seed) drops of and one assumes is dispersed by wind and water hopefully to washed up on a beach several miles away. The lower half (the seed tends to be smaller) however doesn't appear to be particular dehiscent and I suspect that these seeds get either buried in the sand around the parent plant or if the infrutescence disintegrates somewhat you might get a tumbleweed effect. Either way these lower portions may well end placing several kin seeds in close proximatey.

This is perhaps why this plant was chosen for this work?

Interestingly similar behaviour is exhibited by beet (Beta vulgaris - Chenopdiaceae). Seabeet (B.vulgaris ssp. maritima) have dense fused woody fruitheads bearing 2-5 seeds.

Thinking through your idea a bit more, it's interesting to speculate on the consequences of fleshy fruits. Dispersal by passing through an animal gut strikes me as a situation where several seeds may be deposited in close proximity and those seeds may or may not be kin.

Not sure if that answers all your question?
I'm afraid I've had a fair amount of wine this evening. :-)

   
Ichthyic



Posts: 3325
Joined: May 2006

(Permalink) Posted: June 16 2007,13:35   

Quote
Seeds are sensitive to nitrate levels in the surrounding medium. Where established plant are growing soil nitrate levels tend to be low. If levels are high it's suggest a low competition.
Similarly soil temperate fluctuations are used as a measure of competition. In an established environment the soil is insulated somewhat from the suns radiation during the day and losing heat during the night.
In bare/cleared areas diurnal soil levels can fluctaute wildly and again many seeds will repsond to that.
I have to do a lot of wild seed germination in my job and use of trace levels of KNO3 and comparison of constant and alternating incubator tests are a standard starting point.


yes, I understand the potential mechanisms, but to invoke kin selection, there has to be quantitative differences shown between kin and non kin wrt these mechanisms.

It would surprise me greatly if it is even roughly accurate these questions have not been tested by botanists decades before now.

Quote
Interestingly similar behaviour is exhibited by beet (Beta vulgaris - Chenopdiaceae). Seabeet (B.vulgaris ssp. maritima) have dense fused woody fruitheads bearing 2-5 seeds.


similar behaviour meaning differential behavior wrt to kin?

do you have the reference?

so I still remain unclear:

Is this REALLY the first time kin selection has been demonstrated in plants?

--------------
"And the sea will grant each man new hope..."

-CC

  
nuytsia



Posts: 131
Joined: June 2006

(Permalink) Posted: June 16 2007,21:38   

[quote=Ichthyic,June 16 2007,13:35][/quote]
 
Quote


 
Quote
Interestingly similar behaviour is exhibited by beet (Beta vulgaris - Chenopdiaceae). Seabeet (B.vulgaris ssp. maritima) have dense fused woody fruitheads bearing 2-5 seeds.


similar behaviour meaning differential behavior wrt to kin?

do you have the reference?

so I still remain unclear:


Sorry! The comparative with Beta is that the seeds are dispersed in clumps (and they are a coastal species). So when germination takes place you can have a situation where several kin might be growing together. From observations from germinating Beta, seedlings are usually staggered over a few weeks. So would the seedlings allow for kin or do they try to suppress competition?

My interest in your original comment was on the aspect of dispersal mechanisms and the possibility for kin recognition. As you say some mechanisms might lend to this more than others. Ants and animal gut (myrmechory and endozoochory) over wind (anemochory)?

 
Quote
Is this REALLY the first time kin selection has been demonstrated in plants?


Don't know if this is a first but I've just read through your discussion on PT.
Related to that discussion - I don't think there are as many botanist as there are zoologist.... because "everyone" knows plants are boring! :angry:

I had some knowledge of plant root interactions but I haven't read on anything like this before. I was familiar with allelopathy and the use of plant root exudates as a cue for the germination of some parasitic plants. Of what I've read it's seemed obvious there's a lot going on in the soil we don't know about.

Cool little paper (I actually grabbed it this morning). It'll be interesting to see what follows this.

   
Ichthyic



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Joined: May 2006

(Permalink) Posted: June 16 2007,21:49   

Quote
Cool little paper (I actually grabbed it this morning). It'll be interesting to see what follows this.


indeed it will.

you might also be right about the total numbers issue; I only had one botanist as a friend in grad school, even though all the eco/bot/zoo guys were housed in the same building.

I do tend to agree that plants are often overlooked; unfortunate since they have a great many examples where one can observe speciation from directly trackable mutations in the field, just for one thing (I can think of a dozen different papers on polyploidy and new species for example).

plant genetics is damn fascinating stuff.

--------------
"And the sea will grant each man new hope..."

-CC

  
nuytsia



Posts: 131
Joined: June 2006

(Permalink) Posted: June 17 2007,01:32   

Yes there aren't many posts here on plants and this I think is the first one on living plants! :p

I'm involved in a small Australian conservation program and we've been trying to fund a few honors projects on seed biology and we've basically been told there that the students aren't interested.
It's a bit frustrating really.

   
Ichthyic



Posts: 3325
Joined: May 2006

(Permalink) Posted: June 17 2007,13:13   

Even with Irwin being from that part of the world, i have gained a long-term impression that conservation efforts in Australia are difficult to push at the best of times.

What's the impression from actually being there?

--------------
"And the sea will grant each man new hope..."

-CC

  
nuytsia



Posts: 131
Joined: June 2006

(Permalink) Posted: June 18 2007,03:48   

It's hard to say really. I've been out here 18 months and the circles I move in here and back in the UK are conservation minded.
In some way Australia seems a little more on top of their game. They take quarantine/plant health issues far more seriously than Britain does.
Green politics seems to be highly polarised at times. The major employer (by some margin) in Tassie is forestry and "tree huggers" are seen as public enemy number one by many. In more rural areas a green sticker on your car will get it vandalised fairly rapidly. The last election here I was rather startled to see large mobile signs in town say "Don't vote green". No actual alternative stated, just don't vote green.
I read somewhere a little while ago that Australia's atitude to it's wildlife is a legacy of British settlement. People desperately trying to change the land into a second Britain. In part it makes sense many of the original settlers didn't want to be here, after all.
Driving through central Tasmania you can kind of see that. It's pretty depressing. Huge tracks of land devoid of native trees. Hedgerows of Hawthorn. Windbreaks of Poplar (in areas prone to drought). Willow choked waterways. The commonest birds in towns are  Housesparrow, Starlings, Blackbirds, Pigeons and Goldfinches. There are a few places where you're hard pushed to find a native bird. (Edited: and still sounds bad...)
Australian attitudes to Australia do seem to be changing. Friends here comment on there parents thinking of the UK as home even if they were born in Australia. Most of the people I meet are pretty proud of being Australian and that attitude is kind of trickling down into it's native heritage as well. So perhaps the next generation will be far more pro-active in trying to preserve the native flora and fauna.

Presently in the circles I move, the feeling can get pretty dark, with lots of problems and little funding.
It felt a bit like that in the UK too, but Britain has only a fraction of the biodiversity that Australia has.

Botanising in Western Australia is pretty mind blowing stuff. On my first trip out I couldn't recall what I'd done in the morning by the middle of the afternoon. :-)
There, I ended on a high note.

   
Henry J



Posts: 4565
Joined: Mar. 2005

(Permalink) Posted: June 18 2007,22:41   

Re "You can hard pushed to find a native one in some places."

Crikey.

Henry

  
nuytsia



Posts: 131
Joined: June 2006

(Permalink) Posted: June 19 2007,03:49   

OoopS!
I knew I should have gone for the one word answer.
"Yes."  :D

   
Richard Simons



Posts: 425
Joined: Oct. 2006

(Permalink) Posted: June 19 2007,21:50   

Ichthyic: I agree that it is surprising that it has not been done before but I suspect that they are probably correct. Some root competition studies (between plants of two species, or plants of the same species) were done in the 50s and 60s but not much since that I know of (I have been out of the area for a while so I could be out of date here). I was slightly involved in root studies in the 60s and 70s and a major problem was getting the soil off the roots. Even a small amount can have a large effect on the dry weight and any macroscopic organic matter is almost impossible to remove. We used to wade into a local stream and use that as our running water source (drains quickly get plugged by soil). I would hate to have to separate two interwoven root systems, although I suppose these days there could be biochemical methods for estimating the amounts of each.

Another problem is that some roots are very sensitive to light and even a few seconds exposure can check their growth so clear pots or glass-walled pits are limited in their usefulness.

Roots are altogether frustrating to deal with and publications on root growth and morphology generally come slowly so very little has been done in recent years, really since the rise of 'publish or perish'. Most research on roots focuses on nutrient uptake, including VAMs (vesicular-arbuscular mycorrhiza - fungi that live in close association with roots and are important in nutrient uptake).

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All sweeping statements are wrong.

  
Ichthyic



Posts: 3325
Joined: May 2006

(Permalink) Posted: June 19 2007,22:01   

Quote
I would hate to have to separate two interwoven root systems, although I suppose these days there could be biochemical methods for estimating the amounts of each.


yes, if the issue is a physical one, why not simply tag the plants with a molecular marker?  then you don't have to worry about extracting the specific roots for an individual plant any more.

moreover, it would seem likely that intraspecific competition would be measurable in at least some species via easier to sample mechanisms.

overgrowing, allelopathy, or some other easily measurable thing.

--------------
"And the sea will grant each man new hope..."

-CC

  
Richard Simons



Posts: 425
Joined: Oct. 2006

(Permalink) Posted: June 20 2007,21:22   

Quote
why not simply tag the plants with a molecular marker?

I'm sure it could be done but it might not be easy to find a suitable marker. It would have to be something that is easy to get into the roots, does not interfere with root activity and is not easily moved from one root to another. To be useful it should also constitute a predictable fraction of the root mass as the aim would be to get an idea of the amount of root, not just its distribution.

BTW I wonder what the presence of related / non-related roots does to root activity, which is not necessarily closely correlated with root mass or root growth?

--------------
All sweeping statements are wrong.

  
Ichthyic



Posts: 3325
Joined: May 2006

(Permalink) Posted: June 20 2007,21:27   

what about one of the UV luminescent markers?

I've seen those used in plants before, but I don't know how it gets distributed in root cells.

Quote
BTW I wonder what the presence of related / non-related roots does to root activity, which is not necessarily closely correlated with root mass or root growth?


root activity meaning water/nutrient uptake rate?

--------------
"And the sea will grant each man new hope..."

-CC

  
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