Phylogenomics and generic limits of Dypsidinae (Arecaceae), the largest palm radiation in Madagascar

Abstract

With 178 species, palm subtribe Dypsidinae is one of the largest plant radiations on Madagascar. A well-resolved species-level phylogeny is required not only to unpick the drivers of this spectacular radiation, but also to define natural and useful generic limits in this taxonomically difficult group. The only recent taxonomic revision of Dypsidinae recognised just four genera, including the large genus Dypsis (currently with 172 species), which was considered impossible to divide further based on morphology alone. Here we describe the first comprehensively sampled species-level phylogeny of Dypsidinae, including 157 described species (88% of the subtribe) as well as 10 samples of uncertain taxonomic identity (potentially new to science). Our tree is based on target sequence capture data for 161 nuclear DNA loci. The phylogenetic relationships recovered render Dypsis s.l. paraphyletic, requiring the resurrection of two previously synonymised genera. In total, we recognise six genera in Dypsidinae (Dypsis, Chrysalidocarpus, Marojejya, Vonitra, Lemurophoenix, Masoala), all of which are monophyletic and consistent with morphology.

A plastid phylogenomic framework for the palm family (Arecaceae)

“…Thus, plastid phylogenomics have been adopted extensively in recent studies of plant lineages both at deep and shallow taxonomic levels, such as in liverworts [68], ferns [69,70], gymnosperms [71], and angiosperms [5,10,13,31,34,37,[72][73][74], providing critical insights into the recalcitrant phylogenetic relationships within these groups. In contrast with the continuously increasing body of nuclear-based palm phylogenomic studies [39,41,49,[59][60][61][62][63], a comprehensive generic-level plastid phylogenomic study of the family is still lacking [47,58]. Here, we conducted a plastid phylogenomic analysis of palms based on a nearly complete generic-level sampling and aimed at (1) shedding new light on the relationships among tribes, subtribes, and genera of palms and (2) evaluating how plastome and nuclear histories differ across the family.…”

“…They represent one of the most diverse monocot families with ca. 181 genera and 2600 species [40][41][42], which are classified currently into five subfamilies and 28 tribes based on the results of extensive molecular phylogenetic studies [40]. Members of the palm family can be readily identified by their "woody" type growth, with primary thickening of their vascular tissues, plicate leaves with unique development, and inflorescences subtended by adaxial two-keeled bracts [43].…”

“…As an ecologically and economically important angiosperm family, the palms have attracted the attention of many botanists and evolutionary biologists [25,39,[41][42][43][44][45][46][47][48][49][50][51]. Molecular phylogenetic studies have greatly advanced our knowledge of the taxonomy and phylogeny of palms.…”

“…However, some tribal-level relationships in Arecoideae, Ceroxyloideae, and Coryphoideae were poorly resolved in this phylogenetic tree. Multiple phylogenomic studies based on large-scale nuclear or plastid genomic data were also conducted recently in different palm lineages, such as in Arecoideae [39,48], Dypsidinae [41], Calamoideae [49], Lepidocaryeae [61], Phytelepheae [62], Geonomateae [63], Brahea Mart. [64], and Raphia P. Beauv.…”

Genomic signatures of past megafrugivore-mediated dispersal in Malagasy palms

“…We selected species from the western part of the island, where megafrugivore animals were possibly most abundant in the past (Crowley, Godfrey, & Irwin, 2011). These savanna animal-dispersed palm species can be classified in three fruit size classes: large megafruits (30 cm in average lenght - Borassus madagascariensis ), medium-sized megafruits (5.5 cm - Hyphaene coriacea , 4.4 cm - Bismarckia nobilis ) and small fruits (< 4 cm; 1.3 cm - Chrysalidocarpus madagascariensis [previously Dypsis madagascariensis , Eiserhardt et al, 2022]) (Table 1). The relatively small fruits of C. madagascariensis can still be dispersed by extant frugivores (e.g., Eulemur macaco ; Adany et al, 1994), whereas the megafruits of the other three species are too large to be swallowed and dispersed by any extant native frugivore on Madagascar (Perry & Hartstone-Rose, 2010).…”