Every tree species has its unique story, but the Seychelles’ endangered coco de mer, or sea coconut palm tree, stands out with its distinctiveness. A recent study, published in Scientific Reports, sheds light on the surprising reproductive strategy of this iconic tree, challenging common assumptions about inbreeding depression in endangered species.
With only 8,200 individuals remaining, the coco de mer has faced challenges, including habitat decline and seed poaching for its remarkable seeds, which can weigh up to 18kg. Despite its limited range, this giant palm tree continues to captivate scientists and enthusiasts alike.
Contrary to expectations, the study reveals that inbreeding does not pose a significant threat to the coco de mer’s survival. Inbreeding depression, a concern for many endangered species, occurs when tiny populations have limited mating options, leading to weaker offspring. However, the coco de mer seems to defy this pattern.
Female coco de mer trees, though rare, have a diverse pool of mates to choose from. Multiple father trees pollinate them, and the research indicates that offspring survival improves when the parent trees are more closely related. This challenges the typical notion of inbreeding depression and suggests that the coco de mer may suffer from outbreeding depression, where offspring face similar deleterious consequences.
Chris Kettle, a co-author from the Alliance of Bioversity International and CIAT, emphasizes the significance of these findings for both conserving the coco de mer and potentially informing the conservation of other endangered trees. The study highlights the importance of understanding the unique reproductive ecology of species and challenges the general assumptions about inbreeding.
The absence of inbreeding depression in the coco de mer may be attributed to various factors related to the species’ evolution in isolation on islands. The researchers stress the importance of continued protection of the Vallée de Mai World Heritage Site, the largest stand of coco de mer, and the preservation of the endemic gecko, a vital pollinator for the tree.
The study provides valuable insights for the conservation and restoration of the coco de mer, suggesting strategies such as exposing seeds to a broad range of pollen donors and emphasizing planting efforts near mother trees. While the coco de mer may be an anomaly in terms of reproductive strategy, the research encourages further exploration of high-resolution genetic analysis for threatened tree species worldwide. Future steps for the coco de mer may include addressing the challenges of reintroducing the palm to areas where it faced clear-cutting centuries ago.