Darwin’s Doubts Revisited: Japanese Orchids Reveal Evolutionary Risks of Self-Pollination.

A team of researchers from Kobe University has discovered rare orchid species in Japan that reproduce entirely through self-pollination, never opening their flowers. This remarkable botanical finding not only highlights a unique reproductive strategy but also echoes Charles Darwin’s long-held skepticism about the evolutionary viability of such plants.

Over a century ago, Darwin cautioned against the dangers of perpetual self-fertilization in plants, famously stating that nature “abhors perpetual self-fertilization.” Botanist Suetsugu Kenji from Kobe University encountered a real-world example of this phenomenon on a handful of islands in Japan’s Northern Ryukyus—Kuroshima, Takeshima, and Yakushima—where certain orchid species propagate without ever blooming.

“I’ve always been fascinated by Darwin’s concerns regarding self-pollinating plants,” said Suetsugu. “Finding orchids that never open their flowers presented the perfect opportunity to reexamine the genetic and environmental conditions that make such a lifestyle possible.”

Working alongside local plant enthusiasts, Suetsugu and his team spent over a decade monitoring more than a hundred individual orchids. Their long-term field observations confirmed that these plants consistently reproduce without opening their flowers, a trait unseen in any other wild plant species.

To further understand the phenomenon, the team conducted detailed genetic analyses. Their findings, published in the Proceedings of the Royal Society B, revealed extreme genetic uniformity within the orchid populations—conclusive evidence that these species rely exclusively on self-pollination.

Interestingly, the study also uncovered that these orchids evolved from insect-pollinated ancestors that already exhibited very low genetic diversity. In this region, insect pollination proves largely ineffective. The native fruit flies responsible for pollination have limited flight ranges, often transferring pollen only between flowers on the same plant or those very nearby. As a result, even cross-pollination fails to introduce significant genetic variation—making it functionally similar to self-pollination.

Suetsugu pointed out, “Darwin feared that self-pollinating plants would eventually accumulate harmful mutations and reach an evolutionary dead end. While that risk remains, our data suggest that in such low-diversity environments, self-pollinating orchids might actually have an advantage by reliably producing fruit.”

Yet, the evolutionary edge may be short-lived. The researchers estimate that these orchid species are no more than 2,000 years old, and their complete lack of outcrossing raises concerns about their long-term survival—particularly in the face of climate change and habitat disruption.

“These orchids challenge our understanding of plant evolution,” Suetsugu noted. “But their existence may be fleeting. Their rarity underscores how delicate such evolutionary strategies can be.”

Despite the potential fate of these self-pollinating orchids, Suetsugu remains enthusiastic. “Each new discovery brings us a step closer to understanding the full range of nature’s evolutionary experiments.”

Source:https://phys.org/news/2025-05-fate-bloom.html

This is non-financial/medical advice and made using AI so could be wrong.