Non-technical discussion

[Hugh Harries]

Sev,

Thanks for your kind words:

On 2009/11/5 Severino Magat <sev_...@yahoo.com> wrote
Dr Hugh (Harries),  Thanks a lot for your effort to explain the subject terms which . . . could lead to ignoring the message the author wishes to convey . . . to this e-forum . . . Good Day !  Sev Magat

It's nice to receive appreciation, but I wasn't looking for it, rather I was trying to stimulate some discussion about coconut evolution.  You are quite right to say that people may be put off from reading an e-mail if the subject line is not familiar to them.  That seems to have happened in this case because you replied, but nobody else did (so I have changed the title). 

The emails that I had in mind were from Alan Meerow about two recent publications:
 

• Ambiguous genetic relationships among coconut (Cocos nucifera L.) cultivars . . .
  
• Phylogenetic Analysis . . . Identifies Syagrus as Sister Group of the Coconut

but despite these technical sounding titles, the results can apply to help solve other more mundane problems, for example, mechanisation of harvesting. 

Before anything else, I must admit that I'm not competent to comment on the methods used for DNA analysis, but I would like to clear up a misunderstanding in the first paper where the authors say that "Harries [2] argued for a western Pacific origin, and later [3] opined for an origin in the Malesia biogeographic province (the Malay Peninsula, Indonesia, the Philippines and New Guinea)".

The Pacific speculation was on the origin of a wild coconut and, even though others accepted the idea, I eventually realized that the wild coconut originated by floating in the Tethys Sea. The Malesian origin was for a domestic coconut, and I also modified that idea by dating it at a period when rising sea-levels were submerging parts of one low-lying, continental region which eventually became the Malay Peninsula, Indonesia and the Philippines. 

The contrasting characteristics of the two forms convinces me that they could only co-exist in isolation from one another. Their subsequent introgression was a key event (and continues even now) so that all tall Cocos nucifera seen today are introgressed to a greater or lesser extent (including the Niu kafa and Niu vai),  For 30 years my ideas on origins, dissemination and introgression have been cited, not always favorably, but they have not been seriously challenged.

Until now? Which is why I am writing this.

In the second paper, Alan Meerow and his colleagues appear to be resuscitating earlier ideas of a south American origin because their results ". . . might indicate that an Atlantic dispersal of the progenitors of the coconut is likely, perhaps along now submerged mid- to south Atlantic stepping stones, since the diversity of Syagrus is concentrated in Eastern Brazil (Figs. 1–2). But as this event precedes the Andean orogeny (Fig. 2), a Pacific coast dispersal from a broadly distributed lowland rain forest ancestor of Syagrus and Cocos cannot be ruled out.

As with DNA analysis, I am not qualified to question the geology of continental south America but I can think of three points to make:

1. When the Andean orogeny uplifted that land mass to an altitude of 4,000 m, the primordial coconut remained floating at sea-level;
   
2. Whether continental temperatures were lowered by ice ages or raised by global warming, the coconut survived where it floated in tropical seas at about 30°C;
3. Coconuts did not evolve on one continent and simply drop into the sea already able to float kilometric, trans-oceanic distances; they evolved by floating between two (or more) land masses, gaining size (in the nut cavity and the fruit husk) as tectonic plates moved apart, centimeter by centimetre.
   

There may be other theories - in 2007 Kenneth Olsen received a $20,000 grant from the National Geographic Society to study coconut DNA in collaboration with Bee Gunn, a research specialist at the Missouri Botanical Garden. They may have ideas of their own.

Finally, how does this all to help solve the problem of the economic mechanisation of harvesting?

That will be the subject of my next e-mail.

Thank you Sev, Alan and anyone else who cares to comment.

Hugh

2009/11/5 Severino Magat <sev_...@yahoo.com>

Dr Hugh (Harries), Thanks a lot for your effort to explain the subject terms which to people who are not familiar with uncommon plant breeding and genetics terminologies could lead to ignoring the message the author wishes to convey. I like the way you explain deep technical or scientific knowledge as you usually relates to your significant experience and research work in many tropical countries. You're a blessing to this e-forum, indeed. More Power ! Good Day ! Sev Magat --- On Wed, 11/4/09, Hugh Harries <hugh.h...@gmail.com> wrote: From: Hugh Harries <hugh.h...@gmail.com> Subject: [Coconut:2783] What is meant by "introgressed-types" To: "Google coconut group" <coc...@googlegroups.com> Date: Wednesday, November 4, 2009, 11:11 PM One member has written directly to me to explain the terms "introgressed-wild-type" and "introgressed-domestic-type" that I used in a recent e-mail about coconut evolution (extract shown at the end). But I am replying via the group to explain why I favour these complicated-sounding categories in the hope that someone else will provide a clearer explanation.. Introgression, or  introgressive hybridization, can happen when two forms that  look different but can cross pollinate grow in one location. The first generation progeny would be quite uniform but uncontrolled pollination at each subsequent  generation would give rise to more variable, populations. In each population  one of the original forms would predominate and individuals  showing the contrasting form  would tend to disappear unless retained by intentional selection. So, for example, the common coconut (typica) on the Indian mainland has thick husk (but is not wild), in Thailand the preferred varieties have less husk and more water (domestic characteristics), while in Samoa individually extreme Niu kafa and Niu vai palms coexist  because the original Polynesian settlers valued both types and looked after them in every generation (palm and human), In summary, virtually all present day coconut populations are introgressed but which characteristics predominate will depend on which ancestral parent was most numerous when they came into contact and to what extent directed selection was more important than chance,  when seednuts were selected for germination. Finally, keep in mind that I am talking about phenotypes - what the palms look like. My guess is that genetic differences will be much less. For instance the extreme types in Samoa may have DNA fingerprints that are more similar to one another than to comparable types in either India or Thailand. . Hugh ============ Extract from previous email: Before domestication the wild-type coconut had a natural coastal range within the tropics  all around the Indian Ocean and halfway across the Pacific without human assistance because it evolved by floating. The domestic-type was selected for drinking and was carried by people to inland and upland sites, and to coastlines that could not be reached by floating. Wherever the wild and domestic coconuts came into contact uncontrolled cross-pollination produced introgressed-types with intermediate characteristics. Ancestors of the Polynesians took the introgressed-domestic-type eastwards into the Pacific - and also westwards to Madagascar - but it was not until the 16th century that coconut completed its global circumnavigation when Europeans took the introgressed-domestic-type to the Pacific coast of America and  introgressed-wild-type to the Atlantic coasts of America and Africa and to the Caribbean.

[lalith Perera]

Dear all,

 

I am looking for Plant breeding Policy documents from different countries. I am very much thankful to those who can send me a copy of that document of each country.

 

Lalith Perera 

---

From: Hugh Harries <hugh.h...@gmail.com>

To: Google coconut group <coc...@googlegroups.com>

Sent: Sun, November 22, 2009 12:10:14 PM
Subject: [Coconut:2816] Non-technical discussion

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