Phylogeny and historical biogeography of the cocosoid palms (Arecaceae, Arecoideae, Cocoseae) inferred from sequences of six WRKY gene family loci.

Arecaceae tribe Cocoseae is the most economically important tribe of palms, including both coconut and African oil palm. It is mostly represented in the Neotropics, with one and two genera endemic to South Africa and Madagascar, respectively. Using primers for six single copy WRKY gene family loci, we amplified DNA from 96 samples representing all genera of the palm tribe Cocoseae as well as outgroup tribes Reinhardtieae and Roystoneae. We compared parsimony (MP), maximum likelihood (ML), and Bayesian (B) analysis of the supermatrix with three species-tree estimation approaches. Subtribe Elaeidinae is sister to the Bactridinae in all analyses. Within subtribe Attaleinae, Lytocaryum, previously nested in Syagrus, is now positioned by MP and ML as sister to the former, with high support; B maintains Lytocaryum embedded within Syagrus. Both MP and ML resolve Cocos as sister to Syagrus; B positions Cocos as sister to Attalea. Bactridineae is composed of two sister clades, Bactris and Desmoncus in one, for which there is morphological support, and a second comprising Acrocomia, Astrocaryum, and Aiphanes. Two B and one ML gene tree-species estimation approaches are incongruent with the supermatrix in a few critical intergeneric clades, but resolve the same infrageneric relationships. The biogeographic history of the Cocoseae is dominated by dispersal events. The tribe originated in the late Cretaceous in South America. Evaluated together, the supermatrix and species tree analyses presented in this paper provide the most accurate picture of the evolutionary history of the tribe to date, with more congruence than incongruence among the various methodologies.

Diversity of leaf anatomy within a single leaflet and between leaflets of four Butia (Arecaceae, Arecoideae) species.

This paper is an investigation into how the anatomy changes within a leaflet and between the leaflets of a single leaf blade of Butia. Four species of Butia were studied: Butiaparaguayensis, B.eriospatha, B.yatay and B.odorata. Changes in the anatomical characters are important because some have been used in keys to help separate the species. Recently, anatomical mid-rib characters were used in a key to separate species of Butia. We found that characters, such as abaxially projected or rounded mid-rib fibrous ring or number and arrangement of accessory bundles, do change within a single leaflet or between the leaflets of a single leaf blade. Growing conditions and leaf developmental maturity are also important factors that influence leaflet anatomy and may cause one to be misled in an identification key based on anatomical characters. We re-emphasize the importance of always sampling from the same part of the leaf, to have a broader sampling, be attentive to the environmental condition and health of the plant from which you are sampling and to consider population differences.

Cyclone tolerance in new world arecaceae: biogeographic variation and abiotic natural selection.

BACKGROUND AND AIMS: Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection. METHODS: New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts. KEY RESULTS: Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0.001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality. CONCLUSIONS: Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas.

Key to Syagrus identification using leaflet margin anatomy: Supplement to "A revision of Syagrus (Arecaceae)".

Presented here is an alternative method of identification for species of the Neotropical palm genus Syagrus. It makes use of anatomical characters found in the leaflet margins and can be used for identification when few other vegetative or reproductive morphological characters are available. This anatomical study demonstrates the vast diversity found in a single palm genus and may also help to gain understanding of some possible relationships within the genus.

Leaflet anatomy verifies relationships within Syagrus (Arecaceae) and aids in identification.

The current investigation was carried out to examine how palm anatomy may coincide with the current molecular analysis including the three recognized clades of Syagrus Mart. and to justify the splitting of acaulescent Syagrus species (e.g. Syagrus petraea (Mart.) Becc.) into several species. Free-hand cross-sections of leaflets were made and the comparison of these verifies the relationships suggested by the molecular data. Free-hand leaflet sections were also found to be useful in the identification of otherwise difficult-to-identify acaulescent Syagrus species. The result and conclusion is that anatomical data is valuable in helping to verify molecular data and that splitting the acaulescent species of Syagrus is justified by the differences discovered in their field habit and anatomy. These differences were used to produce an identification key that is based on the anatomy.

Phylogenetic analysis of seven WRKY genes across the palm subtribe Attaleinae (Arecaceae) [corrected] identifies Syagrus as sister group of the coconut.

BACKGROUND: The Cocoseae is one of 13 tribes of Arecaceae subfam. Arecoideae, and contains a number of palms with significant economic importance, including the monotypic and pantropical Cocos nucifera L., the coconut, the origins of which have been one of the "abominable mysteries" of palm systematics for decades. Previous studies with predominantly plastid genes weakly supported American ancestry for the coconut but ambiguous sister relationships. In this paper, we use multiple single copy nuclear loci to address the phylogeny of the Cocoseae subtribe Attaleinae, and resolve the closest extant relative of the coconut. METHODOLOGY/PRINCIPAL FINDINGS: We present the results of combined analysis of DNA sequences of seven WRKY transcription factor loci across 72 samples of Arecaceae tribe Cocoseae subtribe Attaleinae, representing all genera classified within the subtribe, and three outgroup taxa with maximum parsimony, maximum likelihood, and Bayesian approaches, producing highly congruent and well-resolved trees that robustly identify the genus Syagrus as sister to Cocos and resolve novel and well-supported relationships among the other genera of the Attaleinae. We also address incongruence among the gene trees with gene tree reconciliation analysis, and assign estimated ages to the nodes of our tree. CONCLUSIONS/SIGNIFICANCE: This study represents the as yet most extensive phylogenetic analyses of Cocoseae subtribe Attaleinae. We present a well-resolved and supported phylogeny of the subtribe that robustly indicates a sister relationship between Cocos and Syagrus. This is not only of biogeographic interest, but will also open fruitful avenues of inquiry regarding evolution of functional genes useful for crop improvement. Establishment of two major clades of American Attaleinae occurred in the Oligocene (ca. 37 MYBP) in Eastern Brazil. The divergence of Cocos from Syagrus is estimated at 35 MYBP. The biogeographic and morphological congruence that we see for clades resolved in the Attaleinae suggests that WRKY loci are informative markers for investigating the phylogenetic relationships of the palm family.