Evolution of nepenthes

[StifflerMichael]

I believe also that the 'teeth' on the peristomes of some Nepenthes are adaptations for trapping. A paper was puplished in PNAS (Proceedings of the National Academy of Sciences, a high-quality scientific journal for those of tha might not know) sometime last year which argued quite well that the peristome is the main trapping mechanism of the plant, more so when the peristome is wet (Proc Natl Acad Sci USA. 2004 Sep 28;101(39):14138-43). It seems pretty likely, to me at least, that the insects venture to end of the teeth, loose their footing due to a decreased surface area and slip in...seems quite a bit more effective! It would of been pretty cool if they tested that.

 

[machete]

If I were to bet, it would be that the "teeth" are for keeping prey in more than stopping animals from getting to the prey. Most plants that try to keep animals at bay, develop thorns or spikes pointing out.

 

[Treaqum]

N. bical is one with a symbiotic relationship. The base of the tendril is hollow. The ants build nests in there. I suposse it's like an acasia where the ants protect the plant while feeding it and the plant gives it a home (acasia don't get fed by the ants though).

 

[TyFone]

I think the teeth is a more advanced trap mechanism..
Try to stand on a bit flat wet metal plate(thats hard).. Then try to stand on a wet metal pipe..(thats harder)

 

[TheAlphaWolf]

to expand on the bical thing, the ants get shelter and food since they can get into the trap and pull out big prey (they don't slip and they can swim). and the bical get's it's big prey removed so it doesn't rot.

 

[RainforestGuy]

My observation on these large oversized peristome development are for bringing smaller insects into the mouth of the pitchers. I don't believe for keeping large prey inside. Since it was only N. rajah known to prey on rats, careful observation of its peristome suggest that if rats were to be attracted and kept from escaping, the pitchers themselves would need to be of gargantuan sizes. Rajah does this well. Whereas N. hamata, edwardsiana, macrophylla, villosa, etc. are not huge pitchers and therefore probably fed on ants and smaller beetles which may walk to the end of the "plank" (like pirates having prisoners walk off planks to the ocean) and fall in. Nectar may also collect at the tips making it very slippery and seeing a glistening blob of syrup would attract anything to it. I seriously doubt these exaggerated peristome daggers were meant to keep prey from escaping. A scientific probe into the contecnts of each pitcher will suggest the kind of prey that plant is feeding on and that would end this discussion regarding mammal, bird, shrew or small tiny beetle prey!
With this being said, I am finding it very interesting what people see and believe about these fascinating plants. I just love these plants tremendously!!!!


MM

 

[witzelsucht]

I find it fascinating that Cephalotus has also developed something resembling teeth along the peristome. Since Nepenthes and Cephalotus are only very very distantly related it seems clear that the teeth are an advantage and I agree that it seems more likely to be related to capturing prey. The teeth in Cephalotus aren't very threatening.

The next question in my mind is what is the cost/benefit of bigger/fewer teeth (as in edwardsiana) vs. smaller/more teeth (as in villosa). There may be little difference - ie they both help capture insects at a similar cost to the plants. If that is the case then the difference could be more the result of genetic drift and other factors than the teeth themselves.

If there is a difference in the effectiveness of insect capture in the different sizes of teeth then my hypotheseis would be that it has something to do with the size of the insects. Different size of ants perhaps? If anyone wants to fund me for this study I would be happy to spend a few months on Kinabalu looking into it

Cheers,
Rich