idw – Informationsdienst Wissenschaft

Nachrichten, Termine, Experten

Grafik: idw-Logo
Science Video Project
idw-Abo

idw-News App:

AppStore

Google Play Store



Instance:
Share on: 
08/25/2022 17:03

The wax flowers and their complex relationship

Christian Wißler Pressestelle
Universität Bayreuth

    Wax flowers and numerous plant genera related to them evolved about 33 million years ago. Shortly thereafter, they split into three independent evolutionary lineages, according to a new international study led by Bayreuth plant systematist Prof. Dr. Sigrid Liede-Schumann. A total of 37 genera and 740 species emerged, distributed over the tropics and subtropics worldwide. Only the combination of well-established morphological studies with the latest molecular genetic analysis methods ensures a correct taxonomic description and classification. The research results have been published in the journal "Taxon".

    The wax flowers, which originated in the Oligocene, form the plant genus Hoya, named after the English gardener Thomas Hoy. This genus – as well as the related genera – belongs to the genus group (tribus) of the Marsdenieae, which in turn belong to the large plant family of the dogbane family (Apocynaceae). Researchers from Bayreuth, Singapore, Le Mont Dore (France, New Caledonia), Brisbane (Australia) and Philadelphia (USA) have now re-examined the evolution of the wax flowers and their complex relationship. The result: The Marsdenieae can be assigned to three different evolutionary lineages that formed more than 30 million years ago.

    A small lineage comprises only a few surviving – so-called relict – species that occur exclusively in the South African region and on Madagascar. The two other lineages, however, are much richer, with about 360 species each, and have a completely different biogeographic history. One of them is restricted to Southeast Asia and Pacific Islands: Numerous different species are now widespread in Australia as well as New Caledonia and New Guinea; the New Caledonian species came in two waves from Australia. This lineage includes the waxflower, which is popular as an ornamental plant, but also, for example, the broad-leafed indigo (Marsdenia tinctoria). The other lineage spread over the entire Old World tropics and subtropics and reached tropical America about 21.5 million years ago. From here, about 130 species, including the climbing shrub cundurango (Ruehssia cundurango), which is known as a medicine, spread over the area of the present tropics.

    The discovery of these three evolutionary lineages was only possible because, in addition to morphological studies long established in plant systematics, targeted molecular genetic studies of the Marsdenieae were carried out for the first time. The plant systematics group at the University of Bayreuth analyzed 171 of the 740 species using seven markes both from the chloroplast and nuclear genomes. In this way, some erroneous assignments in earlier taxonomic studies could be identified. As the researchers discovered, there were many parallel developments, especially in flower structure. For example, large funnel-shaped white flowers evolved independently at least five times to adapt to pollinating moths. Because such parallel developments were not recognized as such in former times, some species of the Marsdenieae were often assigned to the wrong genus.

    The study, now published in Taxon, recognizes and circumscribes 37 genera, two of which are described plant-systematically for the first time. In addition, 26 species could be assigned to the correct genus. "For the correct plant-systematic classification of the Marsdenieae species, our study provides a new key based on morphological characters. However, molecular genetic analyses are sometimes indispensable for the reliable genus assignment of individual species. Only on this basis is it possible to reliably clarify how the development of traits within the different genera are related to each other – for example, whether they are independent parallel developments or successive developments in a larger evolutionary context," says Prof. Dr. Sigrid Liede-Schumann, Chair of Plant Systematics at the University of Bayreuth.


    Contact for scientific information:

    Prof. Dr. Sigrid Liede-Schumann
    Plant Systematics
    University of Bayreuth
    Phone: +49 (0)921 / 55-2460
    E-mail: sigrid.liede@uni-bayreuth.de


    Original publication:

    Liede-Schumann, S.; Reuss, S. J.; Meve, U.; Gâteblé, G.; Livshultz, T.; Forster, P. I.; Wanntorp, L.; Rodda, M. 2022. Phylogeny of Marsdenieae (Apocynaceae, Asclepiadoideae) based on chloroplast and nuclear loci, with a conspectus of the genera. Taxon 71(4): 833-875. 2022. DOI: https://doi.org/10.1002/tax.12713


    Images

    Wax flower (Hoya cumingiana).
    Wax flower (Hoya cumingiana).
    Photo: Ulrich Meve.

    The medicinal plant Cundurango (Ruehssia cundurango).
    The medicinal plant Cundurango (Ruehssia cundurango).
    Photo: Ulrich Meve.


    Criteria of this press release:
    Journalists, Scientists and scholars, Students, Teachers and pupils, all interested persons
    Biology
    transregional, national
    Research results, Scientific Publications
    English


     

    Wax flower (Hoya cumingiana).


    For download

    x

    The medicinal plant Cundurango (Ruehssia cundurango).


    For download

    x

    Help

    Search / advanced search of the idw archives
    Combination of search terms

    You can combine search terms with and, or and/or not, e.g. Philo not logy.

    Brackets

    You can use brackets to separate combinations from each other, e.g. (Philo not logy) or (Psycho and logy).

    Phrases

    Coherent groups of words will be located as complete phrases if you put them into quotation marks, e.g. “Federal Republic of Germany”.

    Selection criteria

    You can also use the advanced search without entering search terms. It will then follow the criteria you have selected (e.g. country or subject area).

    If you have not selected any criteria in a given category, the entire category will be searched (e.g. all subject areas or all countries).