Palm stem anatomy: phylogenetic or climatic signal?

Abstract

The diversity of palm stem anatomy is now well known, but no study has dealt with the influence of climatic conditions. Here, we conducted research in order to establish whether this diversity follows a phylogenetic pattern and/or whether it is correlated with climatic factors. To answer this question, 98 genera and 137 species that cover the five palm subfamilies were sampled. Anatomical descriptors and measurements of vessel diameter were used in multiple correspondence analyses (MCAs) and hierarchical clustering in order to analyse correspondences between anatomy and climate [tropical rain forest (TRF) palms vs. palms growing in a climate with a dry period]. Qualitative anatomical descriptors were plotted on a recent phylogenetic tree. MCA outlined correlations between:(1) one-vessel palms and TRF palms; (2) two-vessel palms and 'dry period' palms; (3) small vessel diameter (< 144 μm) and 'dry period' palms; and (4) large vessel diameter (> 183 μm) and TRF palms. From phylogenetic analyses, Arecoideae (and, to a lesser extent, Calamoideae) is defined as the one-vessel subfamily, Coryphoideae as the two-vessel subfamily and Ceroxyloideae with three to several vessels per fibrous vascular bundle. Palm stem anatomy is thus correlated with climate (TRF vs. non-TRF), but also shows a phylogenetic signal. Therefore, it suggests that the diversification of Arecoideae and Coryphoideae coincided with the beginning of their ecological dominance. Baker WJ, Savolainen V, Asmussen-Lange CB, Chase MW, Dransfield J, Forest F, Harley MM, Uhl N, Wilkinson M. 2009. Complete generic-level phylogenetic analyses of palms (Arecaceae) with comparisons of supertree and supermatrix approaches. Systematic Biology 58: 240-256. Barrow SC. 1998. A monograph of Phoenix L. (Palmae: Coryphoideae). Kew Bulletin 53: 513-575. Bayton RP. 2007. A revision of Borassus L. (Arecaceae). Kew Bulletin 62: 561-585. Blach-Overgaard A, Kissling WD, Dransfield J, Balslev H, Svenning JC. 2013. Multimillion-year climatic effects on palm species diversity in Africa.

BeyondGenera Palmarum: progress and prospects in palm systematics

“…() were used heavily as evidence to underpin the GP2 classification, even though they were published after GP2. Since that time, the ‘palm supertree’ of Baker et al ., as it is often called, has been a springboard for many important comparative studies addressing biogeography and diversification (Baker & Couvreur, , , b; Kissling et al ., ; Eiserhardt et al ., ), biome origins (Couvreur, Forest & Baker, ; Couvreur & Baker, ), community assembly (Eiserhardt et al ., ) and the evolution of floral (Sannier et al ., ; Nadot et al ., ; Rudall, Ryder & Baker, ), vegetative (Couvreur et al ., ; Thomas & Boura, ) and chemical (Siles, Cela & Munné‐Bosch, ) traits.…”

Leaf anatomy inAllagoptera(Arecaceae)

“…Consequently, the number of metaxylem vessels in the leaves should not be very different from that of the stems. Therefore, some Allagoptera species are exceptions in the ‘one vessel’ subfamily proposed by Thomas & Boura () for Arecoideae.…”

“…The bundles have an abaxial position in the leaf lamina, agreeing with the results presented by Moraes (). Allagoptera belongs to Arecoideae, defined by Thomas & Boura () as the ‘one vessel’ subfamily, based on the number of metaxylem vessels in vascular bundles of the stem, and it would often be correlated with a tropical rain forest habitat. The vasculature is continuous in the plants.…”

Integrated Chronology, Flora and Faunas, and Paleoecology of the Alajuela Formation, Late Miocene of Panama

“…Most of the woods examined in longitudinal section (22 out of 24) have simple perforation plates and many of the woods (11 out of 38) have elaborate conformations of axial parenchyma (e.g., aliform, confluent, or wide bands). The rarity of growth rings, the presence of very large mean vessel diameters, abundant axial parenchyma, and the presence of both one- and two-vessel palms are all features found in taxa typical of Neotropical moist forests and rainforests [23, 24, 26–28]. …”