Phylogenetics and diversification history of African rattans (Calamoideae, Ancistrophyllinae)

Abstract

Even though African rain forests display high levels of local species diversity and endemism, their lower continental species diversity when compared with the Neotropics and Asia is paradoxical. This disparity is mainly thought to be linked to either important extinction events during the Pleistocene or at the Eocene-Oligocene boundary. African rattans or climbing palms are one of the most diverse clades of palms in Africa, representing one-third of all known species. Here, we reconstruct the phylogeny and temporal evolution of African rattans (Arecaceae: Calamoideae: Lepidocaryeae: Ancistrophyllinae) to test the two main hypotheses of palm evolution in Africa. We constructed a near-complete, dated species-level phylogenetic tree for subtribe Ancistrophyllinae using plastid and nuclear markers. The generic relationships between Ancistrophyllinae were fully resolved and species-level relationships are well to weakly supported. Ancistrophyllinae diversified during the Eocene with most species originating during the late Miocene after 10 Mya. This result is in agreement with several other studies suggesting a pre-Pleistocene origin of the extant African flora. Ancistrophyllinae display an anti-sigmoidal lineage-through-time plot with a moderate overall extinction fraction. Our simulations suggest important roles for an ancient extinction event at the Oligocene-Eocene boundary. In contrast, the hypothesis of an important extinction event in palms during the late Pliocene at 3 Mya is not supported. We suggest that the evolutionary history of African rattans has undergone a constant diversification rate punctuated by one or several important extinction events during the first part of the Cenozoic with most species diversity accumulating during the late Miocene and Pliocene.

Plant phylogeny as a window on the evolution of hyperdiversity in the tropical rainforest biome

“…For example, in palms, numerous species‐level studies have already been conducted in specific genera, often yielding useful insights into the diversification history of certain TRF areas (e.g. Neotropics, Roncal et al ., , ; Freitas et al ., ; Afrotropics, Faye et al ., ; Asian tropics, Bacon et al ., ). However, genera or similarly sized clades are usually geographically restricted, limiting the generality of such studies.…”

New species of Uvariopsis (Annonaceae) and Laccosperma (Arecaceae/Palmae) from Monts de Cristal, Gabon

“…To date none of these species have been collected flowering or fruiting, however, the vegetative characters alone suffice to clearly distinguish them. The total number of species in Laccosperma is now 7, although new species are yet to be described from West Africa (Faye et al 2016). …”

“…Laccosperma is distinguished from the latter two by the robust and rounded spines on its leaf sheath and stems coupled with hermaphroditic flowers (Sunderland 2012). Laccosperma was recently shown to be sister to Eremospatha (Faye et al 2016). …”

An endangered West African rattan palm: Eremospatha dransfieldii

“…De Wild. from cenrtral Africa based on phylogenetic analyses of molecular sequence data (Faye et al 2014, Faye et al 2016.…”