Charles R. Clement
2Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, 69067–375 Manaus, AM, Brazil
2Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, 69067–375 Manaus, AM, Brazil
The ar of the original residence of the coconut palm, Cocos nucifera, and also the level of its organic dispersal are not known. Advocates of a southern American beginning must explain why the is not aboriginal there and also why that shows best diversity in southern Asia. Conversely, proponents of an eastern origin must describe why there space no asian Cocoseae and also why the closest botanical relative to Cocos is in south America. Both hypotheses share the usual problems of how, when, where and in what direction long-distance dispersal occurred.
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These obstacles are resolved by accepting the C. Nucifera originated and dispersed by populating arising islands that the coral atoll ecosystem, where establishment conditions impose high an option pressures for survival. As soon as lifted by wave activity onto basically sterile, soilless coralline rocks just over sea level and exposed to the full affect of the sun, seednuts should germinate, root and establish vigorous populations. The cavity in ~ the nut augments the buoyancy listed by the thick husk, which in turn protects the embryo and, by delaying germination, all at once extends viability when floating and also provides a moisture-retentive rooting tool for the young seedling. These adaptations permit coconuts come disperse widely through the coral atoll ecosystem.
The monthly manufacturing of fruit and also the long floating term ensure that viable seednuts room always accessible in the lagoon to replace those ruined by hurricanes and also tsunamis, or to populate newly emerged coral atolls elsewhere. Long-distance dispersal is secondary, because it to be the spontaneous, independent hike of coral polyps on a prolonged geological time range that generated brand-new coral atolls in new areas where the coconuts would certainly be amongst the earliest inhabitants. The coconut palm came to be an intermittent, itinerant, pioneer endemic there, and additionally on perfect beaches on volcanic or huge islands and continental coastlines.
Keywords: Coconut palm, Cocos nucifera, coral atoll ecosystem, coral island, floating duration, lagoon, long-distance dispersal, migration, slow germination
When coconut palms (Cocos nucifera) are the subject of a scientific report, the introduce paragraphs can mention only a few of the multiple provides that do this pan-tropical crop invaluable to hundreds of smallholder farmers. A discuss the beauty and familiar appearance of coconut palms is hard to resist, and may be portrayed by a snapshot showing the graceful stems, sustaining a crown of fronds, curving end a dry lagoon, into which the ripe fruit can fall and float. The challenge of managing a long-lived monocotyledon the unknown beginning that can not be vegetatively propagated may additionally be mentioned.
Coconut palms are generally recognized as either high or dwarf, however intermediate growth habits (natural or man-made hybrids) are generally encountered. Relying on circumstances, the fruits vary in size, shape and also number, yet the wide selection of provides of practically every part of the coconut palm is common to all. The assumption that all contemporary coconuts are cultivated, and that their wild progenitors have been displaced and can no longer be recognized, has actually prejudiced research right into the origin and mode of dispersal of C. Nucifera. Wild coconuts developed naturally and also dispersed by floating without any kind of need for human assistance. Also though it to be demonstrated the coconut seednuts have the right to still germinate after ~ floating in sea water for as much as 110 days (Edmondson, 1941), inter-continental, trans-oceanic movement is generally attributed to seafarers, both old and modern. Opinions differ as to the center of origin, natural and human-mediated dispersal range, fruit size and proportions the buoyant fibrous mesocarp, particle cavity and also endosperm composition.
Coconuts were when the exemplar the botany"s "first family" – Principes – however recently, as the financial value that copra (dried coconut kernel) decreased in the 1960s, coconuts have pertained to be regarded as the unknown origin and also not endemic anywhere. Those coconut palms in abandoned commercial plantations top top Pacific islands have actually been condemned together an ‘artificial forest’ in contrast to ‘native woodland vegetation’, and also were ‘so widespread’ the the coconut became accepted together ‘typical that the vegetation’ on south Pacific atolls, such together the Tuamotus, ‘where in the 1830s that was rarely or non-existent’ (Stoddart, 1968). Yet, however rare, coconuts absolutely existed in the Tuamotos as long earlier as 1270–1360 year BP (Lepofsky et al., 1992) and also may have actually been current as wild coconuts prior to Polynesians presented the residential sort (Harries, 1978).
Hence, wild coconuts definitely evolved naturally and also dispersed by floating without any type of need for assistance before humans appeared, because the genus sail from sister genera countless years earlier (Baker and also Couvreur, 2013). Therefore, the attributes that permit seednuts come float, continue to be viable for long periods and also germinate in an overwhelming circumstances are central to knowledge coconut"s evolution.
It is the objective of this approach to propose that coconuts evolved and also dispersed in ~ the coral atoll ecosystem. In for this reason doing, how the attributes of wild coconuts may have developed will become clear. This will likewise suggest answers to some of the long-standing questions around the origin and dispersal that the wild coconut, together topics for further research:
Is its origin in Asia or America?
Is it native anywhere?
Did that disperse eastwards or westwards?
Did the float and establish spontaneously?
If so, just how widely did the spread?
When and also where did every this happen?
ORIGIN and DISPERSAL
Wherever that originated, and also by whatever way it dispersed, the coconut palm gracefully curving over a lagoon (Fig. 1) is not picturesque romanticism however a true ecological effect. Over there is a positive benefit to the population of coconuts, top top a small island, to have actually a expansion habit the supports a much larger variety of trees through a correspondingly bigger vegetation canopy than would be possible if all the palms thrived erect. As one of the an initial plants to with a new island, the coconut is no in competition with taller vegetation, but only with an additional palm of the same population. Though naturally receiving high light intensity, both indigenous overhead and from sunlight reflected indigenous the sea, every younger palms would certainly be compelled to prosper away from the shade of larger palm canopies over them. Stem curvature is likewise encouraged by the shallow rooting habit resulting from the high water table and undercutting wave action. On a coral atoll, the survival of the coconut palm relies on its capability to madness the freshwater lens the is found above the saline groundwater (Harries, 1981, 1992). These and also other components indicate one island origin, but are not necessarily conclusive.
Origin: Asia or America?
There have actually been propose of both Old human being and brand-new World origins for the genus Cocos. Botanists of the 17th century frequently regarded the species as Asiatic. The taxonomic discussion for one American beginning that Martius (1823–1850) advanced was based on similarities in between cocosoid palms aboriginal to central and southern America. At much the same time, coconut was explained as being in a international land and not used to any useful function in Amazonia (Wallace, 1853). In his publication Origin of grew Plants, de Candolle claimed he had changed his mind when he might find only two factors in favour of one American origin however ten in favour of Asia (de Candolle, 1855, pages 432–434, citing de Candolle, 1884, web page 976). Despite these opinions, one American beginning was wanted by chef (1901) and also his views were embraced by de Vries (1906), that tried to apply the brand-new science of genes to the problem. The succeeding speculation by chef (1910) that the dry climates of inner localities in south America to be the only problems where this palm can be intended to maintain its existence in a wild state was no acceptable to Odoardo Beccari. He had reassigned every Cocos species, except nucifera, to various other genera and suggested that the African species Jubaeopsis caffra had actually many much more affinities through C. Nucifera than any kind of other palm (Beccari, 1917). Today, the nearest botanical family member is in south America (Meerow et al., 2009), although whether it is Syagrus or Attalea is still somewhat ambiguous (A. W. Meerow, USDA-ARS-SHRS, national Germplasm Repository, USA, pers. Comm.), which makes an American beginning seem much more likely and also the absence of one endemic coconut more puzzling.
Strong assistance for Beccari come from a other Italian, Emilio Chiovenda, of the colonial Herbarium, Florence, and also a an international authority ~ above the flora of east Africa. He created ‘La culla del cocco’ (‘The cradle that the coconut’), a evaluation amounting to 185 pages giving in-depth conclusions around botanical, geological and also ethnological arguments in the first part (Chiovenda, 1921) and also historical arguments and also a recapitulation in the second component (Chiovenda, 1923; check out Supplementary Data for a synopsis the Chiovenda"s arguments and conclusions).
Chiovenda"s in-depth contribution was favourably obtained by botanic garden director in brothers (Hill, 1929, 1933) and also Indonesia (van Leeuwen, 1933). Limited support came from the German factory Society, whereby Werth (1933) welcomed an asian origin however not voluntarily establishment. In the USA, the manager of the Arnold Arboretum encourage ‘La culla del cocco’ as substantial and critical consideration of the trouble of American versus Old human being origin the the coconut (Merrill, 1938) and, when criticizing Heyerdahl"s epos Kon Tiki expedition, ultimately reiterated that Beccari and also Chiovenda had actually both ably refuted Cook"s 1901 and 1910 theories on the coconut in America (Merrill, 1954). It is easy, with hindsight 90 years later, to find discrepancies in several of Chiovenda"s statements, however it is same to acknowledge that he was on the right track (Harries, 1999).
Nevertheless, specifically what Chiovenda said is less vital than the truth his job-related was overlooked or misunderstood. Because that instance, Ridley (1930), writing about the dispersal of plants throughout the world, did not cite Chiovenda. Worse yet, Mayuranathan (1938) warned against basing conclusions about the original residence of the coconut on the works of historians, and cited only Chiovenda"s three recapitulation pages complying with the historical debates of the 2nd part. Together a result, Menon and Pandalai (1958) took just one sentence come dismiss Chiovenda together a historian, i m sorry is probably the factor why others who have actually written on the subject of coconut origin and also dispersal show up to have actually missed Chiovenda entirely. These encompass Fremond, Ziller and de Nuce de Lamothe (1966), Tammes and also Whitehead (1969), son (1974) and also Mahabale (1976).
When Martius suggested that the coconut had been transported by currents indigenous islands located to the west of central America come those of the Asiatic Archipelago, he had only viewed coconuts in Amazonia and also had not visited American west coast islands or Asia. Had actually he excellent so and seen the differences between the American coconut populations and also the variability both in ~ and amongst Asian populations, he could have stated that the coconut had floated comparatively quick distances between conveniently placed Pacific islands fairly than implying direct long-distance, trans-oceanic dispersal indigenous America come Asia. Or he could have pre-empted Cook"s ideas and also said the coconuts had been carried in boats throughout the Pacific (see Dennis and also Gunn, 1971, for a review). Although the beginning of coconut need to have arisen well before the genus Homo arose in Africa, some world thought the a wild coconut would be tiny and would certainly require human intervention to account for anything more than regional dispersal by floating.
It was the subsequent speculation by chef (1910), the the dry climates of inner localities in southern America to be the only conditions where this palm might be supposed to preserve its visibility in a wild state, that created Beccari (1917) come respond the C. Nucifera was qualified of keeping its visibility on sea coasts, that ocean currents to be responsible for its wide distribution and that coral islands were the locality best adapted to the voluntarily reproduction of the coconut palm. Citing Darwin, that agreed the coral islands to be mere water-washed reefs ‘to which all the terrestrial products that existed on castle must have actually been transported by the tide of the sea’. He maintained that the coconut palm had established itself, unaided by man, in the Palmyras, the Keelings and probably elsewhere. It to be on islands of this kind, v their scanty soil, nearly level v the water, that any kind of coconut washed up on the beach and able to germinate there is no competition indigenous pre-existing woodland vegetation would certainly grow and also prosper, free from the plenty of enemies that would certainly hinder that independent development on the shores the a continent or on among the good Asiatic archipelago (Beccari, 1917).
Discussing the origin of the coconut, Fosberg (1960) embraced that Beccari and also Chiovenda had detailed the preponderance of proof for coconut as an Old human being plant. In presenting his very own theory, he said it may have actually been trained from a wild types growing what in the current optimum range of the modern coconut, however with a smaller, less satisfactory fruit. End time, better forms were selected and planted and also the original centre the domestication to be lost. Since the coconut grew on lowland tropical continental coasts and also high islands, there seemed no means to small the possibility down come a coral island, and, if coconuts sprout when cast up ~ above the top of the beach, this happens wherein there were planted coconuts nearby.
Domestication in the Indo-Pacific area was additionally accepted by Purseglove (1968, 1972), who cited Beccari, listed that Chiovenda hosted the check out that the coconut source in lands, now submerged, what in the north-western Indian Ocean, and added his own belief that it is not crucial to invoke the help of man in the deliver of plants between the brand-new and Old Worlds, and also vice versa, prior to 1492. He accepted that coconut can not tolerate the shade from vegetation and also realized the an ancestor that had a fibrous mesocarp and the capability to float, and also had developed itself top top coral atolls or brand-new volcanic islands, would be free from such competition. To arrive at its current state, that originated and was trained in Melanesia, however it might not evolve over there in vacuo. The postulated the it was lugged by s currents from southern America come Polynesia, or by a southerly migration when Antarctica had actually a more favourable climate (an idea that has recently been revitalized by Pross et al., 2012).
Although Fosberg and Purseglove taken into consideration that a wild coconut could have survived in a far location, they took because that granted the it would certainly be inferior in size, less useful and not together widely distributed as the grew coconuts that were selected for (unspecified) premium qualities and were planted to replace it, eventually becoming the pan-tropical chop that castle were acquainted with. Like practically all other civilization who have thought around the beginning of the coconut, Fosberg and also Purseglove were constrained through the idea the all the coconuts they discovered were grew varieties that had been planted. As kid (1974) grammar it, inland every coconut tree owes its visibility to man and on the coasts most that them carry out so.
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In contrast to Fosberg and also Purseglove, a testimonial of coconut evolution, dissemination and also classification showed how natural an option for circulation by floating end a long period before human involvement can produce a wild coconut palm through the following characteristics (Harries, 1978): perennial expansion (50–100 years), few fruits (50–100 per year), huge fruit dimension (1–2 kg), special husk (up to 70 % of new weight), plentiful endosperm (200–300 g) through a high oil content (70 %), and slow germination (>200 days). Nobody of this parameters exceed the natural variety found in the Palmae, as exemplified through Nypa and also Lodoicea, however taken together they represent a formidable dispersal mechanism. They additionally represent, an extremely closely, the attributes of coconuts found as far apart as Palmyra Atoll in the Pacific Ocean and also the Seychelles archipelago in the Indian ocean (Harries, 1978). It was also realized the the spontaneous presence of normally dispersed, thick-husked coconuts would make coral atolls habitable before seednuts planted by settlers could bear fruit, however the vital and far-ranging relationship in between slow germination and also the atoll ecosystem was no appreciated at the time.