Molecular phylogenetics of Sarcolaenaceae (Malvales), Madagascar's largest endemic plant family

Abstract

With 72 species belonging to ten genera, Sarcolaenaceae are the largest and most diverse of Madagascar's endemic plant families. Comprising shrubs and trees, with members found in nearly all of this island nation's biogeographic regions, they are characterised by the presence of a distinctive extra‐floral involucre that is more or less accrescent, partially or completely covering or enveloping the fruit. We present the first molecular phylogenetic study of Sarcolaenaceae, using broad sampling that encompasses the family's taxonomic and morphological diversity, including 46 species representing all ten genera and sequence data from one nuclear marker (ITS) and three plastid regions (psaA‐ORF170, psbA‐trnH and rbcL), to reconstruct phylogenetic relationships using Bayesian inference and maximum likelihood. Results confirm the monophyly of Sarcolaenaceae and of eight of the ten genera; the monophyly of Rhodolaena remains ambiguous, although the taxa sampled were recovered in two well supported clades that are coherent in terms of morphology and geography. Only a single species of Eremolaena was available for study. The phylogenetic backbone of Sarcolaenaceae is not fully resolved, making it difficult to identify potential morphological synapomorphies or ecological preferences between and within genera. In the family, two monophyletic groups were, however, found [Pentachlaena + Eremolaena + Perrierodendron (Clade A) and Xyloolaena + Leptolaena + Sarcolaena + Mediusella + Xerochlamys (Clade B)] that are consistent with previous results based on morphology. Expanded species sampling and data from additional, more quickly evolving markers will be needed to produce a fully resolved phylogenetic tree for Sarcolaenaceae, which could then serve as a basis for exploring macroevolutionary patterns and processes in this remarkable family and reconstructing its biogeographic history.

Phenology of a dipterocarp forest with seasonal drought: Insights into the origin of general flowering

“…Recent phylogenetic and fossil data support this origin of Southeast Asian dipterocarps (Ducousso et al., ; Dutta et al., ). Other traits suggest that the Dipterocarpaceae may have evolved in a dry environment, and nearly all species outside of Malesia occur in seasonally dry forest or savanna ecosystems today (Appanah & Turnbull, ), as do their closest relatives, the Sarcolaenaceae, which diverged from Asian dipterocarps 88 million years ago (Aubriot et al., ; Ducousso et al., ). Geological data further indicate that the climate of Southeast Asia was also seasonally dry when the Dipterocarpaceae colonized Southeast Asia from India (Morley, ).…”

Integrative taxonomy and phylogeny of leafless Vanilla orchids from the South‐West Indian Ocean region reveal two new Malagasy species

“…Cases of diversification along West/East environmental gradients have already been addressed several times in Madagascan animals (e.g., Vences & Glaw, 2003;Yoder & Heckman, 2006;Glaw et al, 2009;Vences et al, 2009;Younger et al, 2019). In Malagasy plants, analogous cases of differentiation between western versus eastern species have been also reported within Canarium L. genus (Federman et al, 2018) and several genera of the Sarcolaenaceae (Randrianasolo & Miller, 1999;Aubriot et al, 2016). Nevertheless, it is noteworthy that the group of western Malagasy species has then given rise, by transoceanic dispersion, to V. roscheri in the Southeastern coast of Africa and to V. phalaenopsis in Seychelles.…”

Towards stable classifications

“…Bone, Cribb & Buerki, ; Chase et al ., ). Finally, in this issue, we present papers on fungi and lichens (Auxier et al ., ; Widhelm et al ., ), Alismatales (Platonova et al ., ; Volkova et al ., ), Amaryllidaceae (Souza et al ., ), Ranunculaceae (Lehtonen, Christenhusz & Falck, ), Malvales (Aubriot, Singh & Knapp, 2016b; Aubriot et al ., 2016b) and Malpighiales (Ghislain et al ., ). These and other similar papers are leading towards ever more stable classifications.…”