We use sequences of seven putatively independent, single copy WRKY loci originally isolated from Cocos nucifera in order to resolve the closest extant relative of the coconut, the evolutionary relationships of the other genera in the subtribe, determine how paleohistorical events shaped the evolution and biogeography of the Attaleinae, and demonstrate the utility of WRKY loci for phylogenetic inference within the Arecaceae. Our study focuses on reconstructing the phylogenetic relationships within the subtribe Attaleinae, and represents the most intensive sampling of the group so far in a molecular analysis. Further information on WRKY loci, including details of their evolution and orthology, can be found in the Discussion section of this paper. demonstrated the utility of WRKY genes for phylogenetic inference in Malvaceae. and by differentiating individuals from one another within T. The utility of WRKY loci for determining infraspecific relationships has been demonstrated by genetic mapping in Theobroma cacao L. Thus, to date, molecular systematics using plastid or nuclear markers have failed to unambiguously identify the sister genus of the coconut, determination of which is not only of biogeographic interest, but will also open fruitful avenues of inquiry regarding evolution of functional genes useful for crop improvement. ĭespite the importance of the Cocoseae, a well-resolved phylogeny for this tribe has been elusive, –. (monotypic, found in a restricted part of South Africa), the majority of the genera are Neotropical endemics. Dransf., monotypic), and Jubaeopsis Becc. With the exception of Cocos, two endemics in Madagascar ( Beccariophoenix Jum. Within the Cocoseae, the coconut is part of the moderate-sized subtribe Attaleinae, containing 11–12 genera. One genus, Elaeis Jacq., has both a species endemic to tropical America and another in Africa.
Cocoseae now encompasses 18–19 genera of predominantly Neotropical distribution. In addition to the distinctive endocarp, the tribe is well-marked by its once-branched inflorescence, inconspicuous prophyll, conspicuous and often woody peduncular bract, imbricate petals of female flowers, and a triovulate gynoecium. Uhl and Dransfield formalized the groups as tribe Cocoeae containing 22 genera classified within five subtribes, later reduced to 20 genera in three subtribes (more or less embracing Moore's alliances), with orthographic correction of the name to Cocoseae. The tribe was first recognized informally by Moore as “the cocosoid palms,” denoted by fruits with bony endocarps bearing three germination pores or “eyes.” He further delimited three subgroups as the Bactris Jacq., Cocos L., and Elaeis Jacq. (African oil palm), Bactris gasipaes Kunth (peach palm), and many other species of value in local economies. In addition to the coconut, this tribe also contains a number of other palms with significant economic importance, e.g., Elaeis guineensis Jacq. Moreover, in the recent literature on the subject by coconut geneticists, , there does not appear to be a clear distinction between the deeper phylogenetic history of the genus and its far more recent domestication.Ĭocos nucifera belongs to the monophyletic Cocoseae, –, one of thirteen tribes of Arecaceae subfam. Harries argued for a western Pacific origin, and later opined for an origin in the Malesia biogeographic province (the Malay Peninsula, Indonesia, the Philippines and New Guinea), an opinion supposedly shared by a majority of coconut specialists, but weakly supported with data. Beccari suggested an origin in Asia or the South Pacific, while Moore proposed Melanesia. A neotropical origin of Cocos was first proposed by de Candolle. Because of this wide geographic range, the biogeographic origins of the coconut have been one of the “abominable mysteries” of palm systematics for decades. Cocos nucifera is pantropically distributed, a present day range significantly influenced both by a seed well-adapted to oceanic dispersal and the species' importance to humans –. Besides its paradisiacal connotation, the coconut plays a vital role at many different economic levels. Cocos nucifera L., the coconut, is a charismatic monotypic genus forming a dominant part of littoral vegetation across the tropics.
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