Some thoughts about huge degree of variability in Myrmecodia

[Andreas Wistuba]

Having visited and studied quite a  number of habitats over the last few weeks and also digged through some older threads over the last few days I feel that some of the variation we see in Myrmecodia might very well be caused by hybridization between two or more species that occur in one habitat. 

 

E.g. in these two threads we see plants that all originate from one location but they all seem to be strikingly different: My plants and plants grown by Frank and Jay.

We see plants that all have some characteristics in common, such as the barrel shaped caudex and the blueish flowers but are strikingly different from each other in other characteristics.

 

What, if the red petioles in the "goose" are simply a characteristic that was inherited by a red petioled species such as M. platythyrea which is fairly widespread?

 

The horseshoe like arrangement of entry holes seen in my plant on the other hand might well be a trait inherited by a species such as M. jobiensis.

 

The variation that can be seen at some localities simply is too big for my taste. At one place near Nabire, I could easily count 10 clearly distinctive Myrmecodia "species" within 2-3 hours of intense search. However, several of these seemed to be restricted to just one or a few trees and I could not find them again elsewhere.

 

If we now consider ants as important pollinators that will not cross very large distances it's quite obvious, that most cross-pollination events will happen between plants that grow on just one or a few neighboring trees and in many cases seeds will be just the result of self pollination. If a hybrid plant is self pollinated and the offspring again is self pollinated or pollinated with it's mother or sister plants we'll soon have a kind of inbred strain in which the variability gets smaller and smaller.

 

The result will be exactly what can be seen: You have a population of very similar individuals on one tree or a group of trees that behaves almost like a species. In fact this might be a very effective way to speed up evolution. In fact, hybridization nowadays is considered a very important mechanism in the formation of new species.

 

Just food for thought - just a theory...

[Derrick]

This article may have important bearings on this subject but it only covers one species.  http://www.researchgate.net/publication/230170599_Genetic_relationship_of_myrmecophyte_%28Anthorrhiza_caerulea%29_individuals_within_and_among_territories_of_the_arboreal_ant_%28Dolichoderus_sp.%29_detected_using_random_amplified_polymorphic_DNA_markers

 

Also the subject of reticulate evolution.  https://en.wikipedia.org/wiki/Reticulate_evolution

 

   However, my guess is that ant population control (i e the first subject) may be the dominant force. There is, as far as I am aware, zero in the literature to indicate ANY hydnophyte hybridisation but that probably means nothing.

  Something, I have noticed in widespread taxa is that they sometimes show hints of more prominent features seen in species long distances away.  My thoughts are that such features may be part of their overall genomes that become far more dominant in localised populations because of the 'gardening' controls of resident ants and of course isolation. What a fascinating subject for a PhD.

 

   It has also been hypothesized that ants may relax 'normal' evolutionary forces.

edited.

[Derrick]

Angelina's (Just a beginner) study may have some insights. She reports ants removing petals in M. beccarii.  It would be most interesting to read her study.

[Stone Jaguar]

Andreas:

 

Thanks again for some fantastic images of these plants in natural settings.

 

For what it's worth, I think some of the problems that we have been having identifying these plants stems from our previous assumptions that there were only two related species occulting in sympatry, not three. Based on live material that I now have in hand from Triton Bay and Timika in NW Papua I am now convinced that there are at least three "good" species in the area you visited: Myrmecodia erinacea, M. alata, and what I'll call M. sp. Manokwari (IMO, the original "Goose" is alata, not the very large plant that Frank and I grow).

 

Compounding this problem, the key and description in Huxley and Jebb is a bit confusing. In couplet 10, M. erinacea is distinguished from M. alata by having longer leaves with undulate margins. M. alata is defined as having leaves generally <14 cm long, yet in the actual description later in the text on pg 297, the leaves of M. alata are listed as to 18 cm x 5 cm with extremes at 28 cm x 7 cm. Size here seems rather unreliable when compared to the very distinctive leaves that M. erinacea have.

 

 

I have two live M. erinacea at hand from Timika, and we have images of the mother plant fruiting in cultivation as well. One of the plants is now nearly mature size and has begun to flower (brevistylous) at least once weekly. This is a rather unique-looking species. The leaves are bullate, ~chartaceous, relatively long with very undulate margins. As an aside, I find it to be one of the most attractive Myrmecodia in cultivation. Corollas are very narrow/pin-shaped, tinged with blue at the apex and ~16 mm long.

 

 

Sorry for the photo quality.

 

The brevistylous M. cf. alata that I have here from Frank is the original "Goose" and appears to be very closely related to what your are growing on your end. It is relatively small, with  short, narrow, semi-succulent leaves with few lateral veins. The corollas are small (~10 mm) with the blue-violet tinged anthers located near the tip of the corolla well above the hairs.

 

The very large (my plant's stem is now well over 100 cm in length) plant in the "Goose" posting here, and also shown in the post on Manokwari, Irian Jaya is clearly related to both of the above species, but is quite distinct in several characters apart from its very large size and profuse branching.  Leaves are long, to >28 cm and thin-textured. The flowers are reliably 18-21 mm in length, anthers and corolla are pure white with the very occasional light blue tinge present on the tips of the corolla lobes, and anthers are located low down in the tube just below the hairs.

 

 

Upper flower from Frank's "Goose (= M. cf. alata). Lower flower from my "Goose" (= sp. nov.?). From my perspective, these flowers are clearly not from the same taxon, nor do they match those of M. erinacea.

 

All of these plants share heterostylous flowers, spine-rimmed alveoli, stellate or branched spines, deciduous stipules and yellow fruit. Huxley and Jebb document red/orange petioles occurring in several Myrmecodia populations.

 

After looking at some of your photos on FB, I was reminded of a number of populations of the showy-flowered orchid, Guarianthe (Cattleya) x guatemalensis that I have seen in the wild on the Pacific piedmont of Guatemala. It is still not uncommon to encounter large colonies of these naturally occurring hybrids on the same trees or even branches as both of their parents, G. aurantiaca and G. skinneri. These populations appear to be true syngameons, i.e. a small group of species where natural hybridization and subsequent introgression is occurring and where the still variable and very vigorous hybrid may be in the process of displacing its parents. Originally, at least two of these populations that occurred as visually stable units away from the parents were described as separate species (e.g. Cattleya pachecoi Ames & Correll). You are obviously familiar with similar well-known examples in Nepenthes. I can easily imagine a scenario where two of these three Myrmecodia species could occur in side-by-side sympatry in the area you visited, facilitating cross pollination by "shared" ant colonies, and the subsequent hybrid seed being dispersed by birds to another tree varying distances away. These plants in F1 and subsequent backcrosses would presumably blend the characteristics of the parents to result in something "neither fish nor fowl" when confronted with a key.

 

In closing I would also note that I cannot envisage how a cross between any combination of these three species would result in something that looks like the other. I can, however, see one that resembles the large plant in your collection and some of the plants in your in situ shots.

 

Thanks again for fantastic information and images from your most recent visit to Papua.

 

Cheers,

 

J

[Aurélien]

Hi Andreas,

 

Your therory is really interesting. So, we could assist to a kind of "microspeciation" made by the small distance made by the pollen. This will led to some eugenism or accomodation in a small territory.

 

Thus, albeit I never observe it, fruits of Hydnophytinae are dispersed by apes and birds, am I right ? I suspect that these animals made a biggest distance than ants, and will bring some genetic mixity in the populations, and also variability.

 

What do you think about it, following your experience and observations?

 

The best,

 

Aurélien

[jeff]

Bonjour

 

very interesting discussion

 

M.erinacea is heterostyly  with brevistyle and longistyle  flowers   not M.alata   no ?

 

on M.erinacea  ( H&J )

 

ring of hair halflway  up the tube

 

in brevistyle flower  anthers among hairs or at apex of tube; stigma at hairs

in longistyle flower  anthers at tube apex ;stigma above anthers

 

on M.alata  (H&J)

 

ring of hair  below or at mid tube

anthers  almost sessile  among hair , or in filaments1.5mm  above hairs; stigma below or above anthers

 

on the anthers interesting these blue  black flecks

 

jeff