What happens to pristine island habitats when humans take over?

Untouched natural habitats for plants and animals are becoming scarce on planet earth. Wherever men settle, they hunt and gather and shape the environment to fit their needs – causing enormous pressure on flora and fauna. Cases where humans are totally absent best illustrate how strong this influence is. The Chernobyl disaster of 1986 devastated the lives of many, but was, astonishingly, a huge saviour for local wildlife [1]: when the effects of the explosion forcibly expelled 100,000 humans, nature readily filled the vacuum, albeit at a very high price [2]. Wildlife has to cope with long term exposure to radiation, but, nonetheless, populations of lynx, elk and wolves have boomed in the area.

All across the world, opposite trends prevail. Humans have taken over even remote and once-pristine island habitats. The Seychelles archipelago is one of these. Upon this heavenly group of islands, unique plant and animal species have been evolving in isolation for up to 70 million years in the absence of people. Foremost among these, and endemic to the islands of Praslin and Curieuse, is the Coco de Mer, an exceptional and astonishing plant.

Famous for its sensational seeds

This gigantic palm grows up to 30 m high, produces huge flowers, leaves up to 10 m wide and 20 m long, and the largest fruits and seeds in the plant world! But as extraordinary as it sounds, many things about this species may seem familiar.

You all know how it is with families. The mother does her best for her kids. She nurtures them, provides as much food and shelter as they need, and eventually they leave home to fend for themselves. It’s exactly the same with the Coco de Mer. The enormous fruits, weighing up to 20 kg, grow and develop on the tree for seven years. When they eventually mature, the seeds are released to disperse from the mother. And yet, they don’t move far from home.

A tight-knit family

The Coco de Mer grows in groups where neighbours are all closely related [3]. This means that the most likely mate for a female tree could well be a close family member. Occasionally a far-away male might contribute his pollen to the family group, introducing a little genetic novelty (not too dissimilar to the British Royal Family). But in the case of the Coco de Mer, a tight-knit family group isn’t necessarily a bad thing.

The naturally “structured” populations and peculiar fruits of the Coco de Mer are remarkable ecological features that have evolved over millions of years under the stable conditions on Praslin and Curieuse. As the soils there are naturally very nutrient-poor, the species has developed a way to cope with this. The young seedlings are able to survive their early years using the huge energy store provided by the mother within the giant seeds. Stay-at-home seeds also make use of the nutrients and rainwater that filters down the trunks of the mother palms standing just above them [4]. Yes, inbreeding is high in these populations, but the benefits of a mother’s attention appear to outweigh the potential negative costs of inbreeding [5].

Realm at risk

Nature takes an infinite number of unique forms. The beautifully-shaped Coco de Mer seeds have long been used to make bowls and decorative ornaments, and fetch a high price as tourist souvenirs; very few are left to grow into adult palms. So while the mother tree invests all her energy into her prize offspring, most of these don’t even get a chance of life. Coupled with the insatiable tourist demand for seeds as souvenirs, the forest is becoming increasingly fragmented and eroded, and the devastating effects of serious historical fires can still be seen. The queen of palms is facing real existential threats; is her realm at risk?

Securing a future for flora and fauna

The Chernobyl Explosion gave wildlife an exceptional opportunity to reclaim the land. In the Seychelles, and much of the rest of the world, people will continue to live in close contact with wild plant and animal life; and we need to tread more carefully. UNESCO has declared the islands of the Seychelles a world heritage site, and the trade in Coco de Mer seeds is now strictly controlled.

Humans have already done damage to many natural habitats; by better understanding the life strategies of plant and animal species – how they compete effectively for resources, and reproduce – we can minimise our future impact. Perhaps then wild populations will be able to adapt to the changed conditions, and flourish in the future.

Further information

[1] Newspaper article in The Guardian

[2] Video clip: The Animals of Chernobyl | The New York Times - YouTube

[3] Journal article : Morgan EJ, Määttänen K, Kaiser-Bunbury CN, Buser A, Fleischer-Dogley F, Kettle CJ. 2016. Development of 12 polymorphic microsatellite loci for the endangered Seychelles palmLodoicea maldivica (Arecaceae). Applications in Plant Sciences 4:1500119.

[4] Journal article, Edwards et al. 2015: here

[5] Journal article: Morgan et al. (submitted)