Researchers at the University of Wisconsin–Madison have identified a new species of baobab tree, Adansonia bozy, unique to Madagascar. The finding, published in Taxon, reclassifies northern populations previously grouped with Adansonia za, altering conservation priorities for the endangered trees across the island.
Reclassifying Malagasy Baobabs Through Genetic Analysis
Scientists have long recognized eight distinct species of baobabs distributed across Australia, continental Africa, and Madagascar. Six of those species reside on the Indian Ocean island. Researchers at the University of Wisconsin–Madison, collaborating with teams from the Missouri Botanical Garden and Iowa State University, have now added a ninth species to recognize a new species of baobab tree, Adansonia bozy.
Lead author Nisa Karimi pursued the discovery during her doctoral work in the former Department of Botany at UW–Madison. Morphologically, members of A. bozy
closely resemble Adansonia za, the species with which they were previously classified. However, targeted sequence capture—a phylogenetic method used to isolate and sequence hundreds of genes of interest—revealed significant genetic divergence.
“Despite it sharing morphologies to the species that it was later classified with, [A.bozy] is actually more closely related to two other groups in northern Madagascar than the species it was synonymized with,”
Nisa Karimi, lead author
David Baum, a co-author who has studied baobabs for over four decades, noted that defining plant species requires strict taxonomic boundaries. Any group that we choose to recognize in a taxonomy must consist of organisms more closely related to one another than to anything outside the group, according to Baum.
Navigating Remote Terrain and Slimy DNA Extractions
Collecting samples required fieldwork in remote regions of Madagascar. Because several baobab species share leaf shapes, visual identification in the field proves difficult. Karimi explained that to know what you’re looking at, you have to see them in flower
. Yet each species blooms for only about a month, opening their flowers exclusively after dusk high in the canopy, sometimes exceeding 100 feet above the ground.
Laboratory extraction presented its own obstacles. Plant tissues rich in polysaccharides produced a slimy substrate that tended to fragment high-quality DNA strands. Through trial and error, the research team isolated the clean genetic material necessary for sequencing.
Global Evolutionary History of the Baobabs
Beyond the new Madagascar species, broader genomic research sheds light on how baobabs populated three continents. A global team of plant genetics and genomics researchers—led by Tao Wan and Qing Feng Wang at the Wuhan Botanical Gardens in China alongside Ilia Leitch at the Royal Botanic Gardens, Kew—sequenced and assembled the genomes of all eight recognized species.
The findings indicate that all modern baobabs originated in Madagascar, beginning to diversify into distinct species around 21 million years ago. Ancient hybridization evident in the genomic data confirms that the ancestral species lived and interbred together on the island before geological shifts altered the landscape.
Ice ages and fluctuating sea levels subsequently drove speciation. Within the last 12 million years, seeds and seedlings from Malagasy ancestors floated across the ocean on debris rafts formed by storm-swollen rivers, eventually reaching mainland Africa and Australia.
Conservation Stakes for Endangered Malagasy Flora
The formal description of A. bozy
carries immediate consequences for conservation funding. Because conservation allocations in Madagascar frequently target threatened and endangered species, researchers expect the newly separated species to draw dedicated resources. At the same time, the reassignment of these individuals reduces the recognized population size of A. za
, which may prompt a reevaluation of its conservation status.
Further taxonomic revisions may follow. The research team suggests that another widespread species, A. rubropstipa, may also require division upon closer genetic inspection. Investigators intend to continue field studies across Madagascar to map the island’s botanical biodiversity.
“You can’t conserve anything if you don’t know how to describe and name them and understand how they’re related to other things on the landscape,”
Nisa Karimi, lead author
Funding and Institutional Support
Additional collaborative efforts involved institutions across multiple continents, underpinning a broader scientific effort to document how environmental pressures and ancient oceanic dispersal shaped the survivors.
