Loose Baobabs or upside down trees are serious Danger of extinction. The origin of this plant dates back to Madagascaraccording to a genomic study recently published in Nature. Two of these emblematic species are threatened with extinction. This study on the ‘baobab or upside down tree‘could help design new strategies for its conservation.
Genomic analyzes of all known species of the baobab or upside down treepublished in Naturethat’s what they suggest Madagascar It is the most likely place of origin of this iconic plant. This work provides crucial information about its evolutionary history and could aid in its development Conservation strategies in a constantly changing world.
Loose baobabs or upside down trees Africans, of the genus Adansonia, are recognized in the Malagasy language as the ‘mother of the forest’, as well as the ‘inverted tree” and the “tree of life«. There are eight morphologically distinct species, one of which occurs in Africa, another in northwestern Australia, and the other six are endemic to Madagascar. Nevertheless, the origin of the baobabs or upside down trees It has been a matter of debate due to the lack of fossil evidence.
Researchers in the study, conducted through an international collaboration between Wuhan Botanical Garden in China, Royal Botanic Gardens Kew in the United Kingdom, the University of Antananarivo in Madagascar and Queen Mary University of London in the United Kingdom, conducted genomic analyzes of eight species of baobab or upside down treewhere these data are combined with ecological analyses.
“Its origin has long been debated, given its unusual geographic distribution pattern. This is a matter of fundamental importance to deepen our knowledge of the history of this type of diversification, including the actual habitat suitable for their ancestors. On the other hand, the findings presented here represent a demonstration of the existence of extraordinary plant diversity on the island as a whole, highlighting the need for more conservation research in Madagascar in a changing world,” says Tao Wan, lead author of the research. research in the Wuhan Botanical Garden.
These analyzes suggest that the ancestral lineage of baobab or upside down tree It emerged about 41 million years ago and spread about 20 million years ago. Scientists discovered that the population history of baobabs or upside down trees It is closely linked to geological changes in Madagascar, especially sea level fluctuations.
“Our projection shows that in vast areas of Madagascar, when sea levels were low, changes occurred mainly on the west coast of the island, where the baobabs or upside down trees. The long-term change in sea level (rise and fall), together with local paleogeographical events – such as mountain rising or volcanic activity– they could jointly facilitate the configuration of environmental heterogeneity, which is crucial for the local adaptation of species,” the scientist emphasizes.
This is a remarkable example of species radiation on this island. This process was followed by long-distance dispersal to Africa and Australia. During this speciation process, a surprising thing happened differences in pollination mechanismsinvolving moths, bats and lemurs to obtain nectar as a reward.
“Plants almost certainly arrived in Africa and Australia floating on rafts of vegetation. Their long-distance dispersal was probably facilitated by the Indian Ocean Gyre, an ocean current that circulates southward past Madagascar, where it would collect seeds from the baobab or upside down tree, before the current turns east towards Australia, where they would reach. The current then circulates northwards before turning westwards past Mauritius and back to Africa, where it completes the bend,” Wan explains.
Andrew Leitch, from Queen Mary University of London, added: ‘We are delighted to be involved in this project which is revealing patterns of speciation in nature. baobab or upside down tree in Madagascar, followed by the astonishing long-distance dispersal of two species, one in Africa and the other in Australia. This was accompanied by the evolution of some Fascinating pollination syndromes involving moths, lemurs and bats”.
Re-evaluate the conservation of the baobab or upside-down tree
Based on data including phylogenetic relationships, gene flow and genetic diversity between the different species baobabs or upside down tree are serious Danger of extinctionresearchers point to Madagascar as the most likely center of origin for these trees. This conclusion provides the most coherent explanation for the current data, in contrast to hypotheses that suggest continental Africa or Australia as areas of origin.
From their genomes, they found that two of the Madagascar species have limited genetic variability and are rare, with small population sizes and narrow ecological niches (or habitat preferences), making them vulnerable to climate change and other environmental pressures, such as changing the land use. usage.
Furthermore, they found that a rare species shows evidence of ongoing, long-term interspecific hybridization with a more common species, making the rare species vulnerable to genetic flooding and loss of distinctiveness. “Therefore, we believe that the three rare species should have a high conservation status,” Wan argues.
“This work has provided new insights into speciation patterns in nature baobabs or upside down tree and shows how climate change has affected their distribution and speciation patterns over millions of years,” says Ilia Leitch of the Royal Botanic Gardens, Kew.
Furthermore, the findings allowed the researchers to investigate the conservation strategies and the condition of these plants. For example, propose that a higher conservation status be granted to the two critically endangered species of Malagasy baobabs or upside-down trees: A. suarezensis j A. grandidieri.
The increased levels of inbreeding, low genetic diversity and declining population size suggest that these two species They cannot withstand ecological shocks and may face a serious threat from climate change..
“It would be desirable to conduct more population genomic studies to find out how interspecific gene flow affects their adaptation and speciation,” Wan concludes.