A new study has uncovered the origins of baobabs, the tall and uniquely shaped deciduous trees which are famously spotted on the island of Madagascar. Also known as the “mother of the forest”, other species of these trees are native to Africa and Australia.
The study (‘The rise of baobab trees in Madagascar’) from researchers in the UK, China and Africa was published in Nature on Wednesday (May 15). Here is what it found about the evolution and spread of these trees and the dangers they face now.
First, what are baobab trees?
Baobabs are known for their great heights, with some extending up to 50 metres, and exceptionally long lifespans going up to 2,000 years. In India too, a few baobab trees exist, including one near the Golconda Fort in Andhra Pradesh that is believed to be more than 400 years old.
A path lined with baobab trees in Madagascar. (Via Wikimedia Commons)
The trees have trunks with large circumferences and thin, spindly branches. In local cultures, the trees are also revered because of the multiple uses their parts have, with the fruits and seeds being edible, the seed oil used for cooking and the bark fibre for clothing.
They are also called “upside down” trees because their tops resemble an uprooted plant turned upside down. Many legends surround the nickname, including an Arab one that says “The devil plucked up the tree and thrust the branches into the soil and left the roots in the air.” (‘The Baobabs: Pachycauls of Africa, Madagascar and Australia’ by Gerald E Wickens and Pat Lowe’)
In their book, Wickens and Lowe also wrote about the importance of conserving the tree as it is a keystone species. In any ecosystem, such species provide “essential resources, such as food or shelter, for a guild of animals in return for which the guild of animals provides an essential service, or mobile links, such as pollination or diaspore dispersal.” Simply, the absence of keystone species can have destabilising effects on entire ecosystems, given their centrality to them.
For example, “The baobabs play an important biological role in the conservation of ecosystems of which lemurs, sunbirds and hawk moths are important constituents,” they wrote.
The trees belong to the genus Adansonia, which comprises eight distinct species: Adansonia digitata found in continental Africa, Adansonia gregorii in Northwestern Australia, and six other species endemic to Madagascar.
What did the study find?
The study noted the threats these trees face and studied their genetic makeup. It said that three Madagascar species of the baobab trees are threatened with extinction according to the IUCN Red List of Threatened Species.
The remaining three are listed under the Least Concern category, meaning they do not face significant threats. According to the IUCN, these include residential and commercial development, livestock farming and ranching, which require clearing land.
But even in the case of species which are not directly threatened, “Their declining populations indicate that more rigorous conservation strategies are required to ensure the long-term survival of these culturally and globally important species. For that to happen, a detailed understanding of the genetics of baobabs is urgently needed,” the study said.
Genomic sequencing of the trees revealed an “overall consensus on the monophyly of the Malagasy lineage” from Madagascar. A BBC report on the study said, “According to DNA studies, the iconic trees first arose in Madagascar 21 million years ago. Their seeds were later carried on ocean currents to Australia and also to mainland Africa, evolving into distinct species.”
Building on earlier research, the study said climate change will pose “severe threats” for Adansonia suarezensi from Madagascar, “leading to its extinction before 2080.”
Further, an assessment of Adansonia suarezensis and Adansonia grandidieri suggested high levels of recent inbreeding, and given their distinct place in their ecology and low genetic diversity, they were likely to have “reduced resilience to ecological perturbations and habitat fragmentation”.
Source link : https://indianexpress.com/article/explained/explained-sci-tech/new-study-madagascar-baobab-trees-9335698/lite/
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Publish date : 2024-05-17 03:00:00
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