The sea coconut (Lodoicea maldivica) stands as a remarkable palm, famed for producing the world’s largest seed, often tipping the scales at more than 20 kilograms. The tree itself reaches monumental proportions among palms, sometimes exceeding 30 meters in height. Its leaves are vast and robust, and the seed’s shape has earned it a distinctive, almost human-like silhouette.
Growth is slow: trees take more than four decades to mature, fruits require seven years to ripen, then about six months to break down and two years to germinate. This lengthy development makes specimens outside their natural habitat rare, and the species is listed on the IUCN Red List as endangered.
A multinational scientific team studied Lodoicea maldivica in depth and reported surprising findings. Contrary to some conservation narratives, it appears that inbreeding may not be the decisive threat for this species, especially for populations that exist in small or isolated groups.
On the contrary, mating between unrelated individuals does not seem to induce the severe fitness costs sometimes observed in other endangered taxa. In fact, some evidence points toward the opposite: in this species, what researchers call overbreeding depression can occur when closely related trees mate, reducing fitness in offspring.
Lodoicea maldivica is a visual beacon in botanical gardens and wild landscapes alike. In a photograph taken at the Kandy Botanical Garden in Sri Lanka, the palm’s magnificence is evident, underscoring why it captures the imagination of collectors and scientists alike.
Originally discovered in 1563 by the Portuguese physician Garcia de Orta, this species has a lineage that traces from the Seychelles to the Maldives. De Orta found enormous seeds in coconuts and coined the term maldivian coconut, even though the tree’s natural habitat lies about 2,000 kilometers away, on the Seychelles islands.
Popular collector’s item
How did these massive seeds end up in the Maldives? The prevailing theory is that coconuts washed from Seychelles into the sea, drifting for months until currents carried them toward the Maldives. Their remarkable germination process allows seeds to survive long sea voyages, enabling such improbable journeys.
For centuries, Maldivian traders shipped these colossal nuts to India, where they were valued for supposed medicinal properties and as aphrodisiacs. Today, the seed itself lacks proven pharmacological effects, yet its rarity and symbolism keep it highly sought after by collectors.
Poaching remains the greatest threat to the species. In the wild, Lodoicea maldivica persists on just two islands in the Seychelles, Praslin and Curieuse, where roughly 8,200 individuals survive. The seed is a coveted object for collectors, and illegal trade continues to jeopardize the population.
The latest findings from researchers in Switzerland, the United Kingdom, and the Seychelles challenge a long-standing assumption: inbreeding may not be the primary driver of risk for this plant. The work suggests that endemism and isolation can shape the reproductive dynamics in ways that lessen the role of inbreeding depression.
“The results are not only important for conserving this iconic tree,” said study co-author Chris Kettle, “but they may influence conservation and restoration strategies for endangered trees elsewhere.”
Short-distance mating
Female trees find ample mating partners, often pollinated by several nearby hosts, which maintains genetic diversity. Yet the research indicates that offspring survival improves when parent trees are more closely related, an unusual pattern in plants and a surprise given the species’ isolation.
The evidence shows that cocos de mer frequently favor mating with near relatives. Short-distance matings among related individuals appear to be common, and the pattern may contribute to a balance between genetic variation and local adaptation. What’s more, the so-called overbreeding depression is a real phenomenon in this context, but it operates differently than classic inbreeding costs observed in other species.
Experts emphasize the need to understand reproductive ecology without relying on rigid assumptions. Protecting palm habitats remains essential, and ongoing work recognizes the role of pollinators and habitat integrity as key elements of conservation. A broad view of the palm’s ecology helps safeguard this emblematic species and its associated biodiversity.
In Seychelles’ ecosystems, the absence of strong inbreeding depression may be linked to several factors tied to the island’s long isolation. Studies suggest that rare long-distance pollination events can, on their own, maintain genetic diversity in these ancient trees.
Researchers advocate practical conservation steps, including targeted manual pollination and distributing fertilized seeds across a wide array of pollen donors, especially near mother trees. The goal is to bolster autochthonous seed sets while maintaining genetic flow across populations.
Overall, conservationists are urged to adopt a nuanced view of inbreeding and its significance for threatened plant populations. For species with limited gene flow, like Lodoicea, the traditional emphasis on avoiding any related mating may be less critical than ensuring habitat preservation and maintaining pollination opportunities over time.
Reference work: Nature article on Lodoicea maldivica and its genetics. (Nature. 2023)
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Citations: Environmental studies and botanical research from Swiss, British, and Seychellois teams support these conclusions, highlighting the complexity of genetics in island endemics and the need for tailored conservation strategies.