Wax flower (Hoya cumingiana). Credit: Ulrich Meve.
The wax flowers, which originated within the Oligocene, kind the plant genus Hoya, named after the English gardener Thomas Hoy. This genus—in addition to the associated genera—belongs to the genus group (tribus) of the Marsdenieae, which in flip belong to the massive plant household of the dogbane household (Apocynaceae).
Researchers from Bayreuth, Singapore, Le Mont Dore (France, New Caledonia), Brisbane (Australia) and Philadelphia (U.S.) have now re-examined the evolution of the wax flowers and their complicated relationship. The end result: The Marsdenieae will be assigned to 3 totally different evolutionary lineages that shaped greater than 30 million years in the past.
A small lineage contains only some surviving—so-called relict—species that happen solely within the South African area and on Madagascar. The two different lineages, nevertheless, are a lot richer, with about 360 species every, and have a very totally different biogeographic historical past. One of them is restricted to Southeast Asia and Pacific Islands: Numerous totally different species at the moment are widespread in Australia in addition to New Caledonia and New Guinea; the New Caledonian species got here in two waves from Australia.
This lineage consists of the waxflower, which is well-liked as a decorative plant, but in addition, for instance, the broad-leafed indigo (Marsdenia tinctoria). The different lineage unfold over the complete Old World tropics and subtropics and reached tropical America about 21.5 million years in the past. From right here, about 130 species, together with the climbing shrub cundurango (Ruehssia cundurango), which is called a drugs, unfold over the world of the current tropics.
The medicinal plant Cundurango (Ruehssia cundurango). Credit: Ulrich Meve.
The discovery of those three evolutionary lineages was solely attainable as a result of, along with morphological research lengthy established in plant systematics, focused molecular genetic research of the Marsdenieae had been carried out for the primary time. The plant systematics group on the University of Bayreuth analyzed 171 of the 740 species utilizing seven markers each from the chloroplast and nuclear genomes. In this manner, some inaccurate assignments in earlier taxonomic research could possibly be recognized.
As the researchers found, there have been many parallel developments, particularly in flower construction. For instance, giant funnel-shaped white flowers advanced independently at the very least 5 instances to adapt to pollinating moths. Because such parallel developments weren’t acknowledged as such in former instances, some species of the Marsdenieae had been usually assigned to the mistaken genus.
The examine, now revealed in TAXON, acknowledges and circumscribes 37 genera, two of that are described plant-systematically for the primary time. In addition, 26 species could possibly be assigned to the right genus.
“For the right plant-systematic classification of the Marsdenieae species, our examine gives a brand new key based mostly on morphological characters,” says Prof. Dr. Sigrid Liede-Schumann, Chair of Plant Systematics on the University of Bayreuth.
“However, molecular genetic analyses are generally indispensable for the dependable genus project of particular person species. Only on this foundation is it attainable to reliably make clear how the event of traits throughout the totally different genera are associated to one another—for instance, whether or not they’re unbiased parallel developments or successive developments in a bigger evolutionary context.”
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More info:
Sigrid Liede‐Schumann et al, Phylogeny of Marsdenieae (Apocynaceae, Asclepiadoideae) based mostly on chloroplast and nuclear loci, with a conspectus of the genera, TAXON (2022). DOI: 10.1002/tax.12713
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Wax flowers and their complicated relationship (2022, August 25)
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