Genomic evidence points to a sharp decline in a Fijian bee
A new study of a native Fijian bee indicates that its effective population size has fallen dramatically over approximately the past 150 years. The finding concerns Hylaeus navai, one of several small, canopy-dwelling Hylaeus bees recently identified as endemic to Fiji.
According to a report on the study, published in Ecology and Evolution, the inferred decline coincides with the period since European colonization of the islands. The research examined the demographic history, genetic health, population structure and distribution of six Hylaeus species found in Fiji.
A bee that remained largely overlooked
Researchers discovered six endemic Fijian Hylaeus species in 2024. These bees had been largely overlooked in part because they tend to live, feed and reproduce in treetops rather than in more routinely sampled low vegetation.
The bees are also small: the report describes them as averaging roughly 3.9 millimeters in length. Their small size and canopy habitat may have helped keep them out of view while also making them vulnerable to changes in forest habitat.
The researchers describe the Fijian Hylaeus as carrying pollen internally and appearing specialized on red-flowering canopy plants. That observation challenges older assumptions that bees cannot see red. Their probable dependence on forest canopy environments and potentially limited foraging ranges are central to the conservation concern raised by the study.
What an effective population decline means
The study’s estimate concerns effective population size, a genomic measure used to infer how much genetic contribution a population has maintained across generations. It is not simply a head count of living bees. Even so, a steep reduction in that measure can signal a serious loss of genetic diversity and resilience.
The report characterizes the result as an extreme example of pollinator decline. Pollinators support wild plants and agricultural production, while habitat loss and pesticide use have contributed to broader concerns over the status of bees and butterflies worldwide.
Why the finding matters
- The species appears to be a forest-canopy specialist with a potentially restricted range.
- Its decline is inferred from genomic data over a long historical period.
- The work highlights how poorly sampled habitats can conceal vulnerable pollinator species.
- It adds urgency to understanding Fiji’s endemic bee diversity and the habitats those species depend on.
The new result does not identify a single demonstrated cause for the inferred decline. Instead, it places the demographic shift in a timeline that overlaps with major human and environmental change in Fiji after European colonization. The authors’ ecological observations underline why continued study of these small, canopy-associated bees is important: species that are hard to observe can also be easy to miss in conservation planning.
For the Fijian Hylaeus group, routine sampling of treetops was crucial to recognition in the first place. The genomic evidence now suggests that documenting where these bees occur, how their populations are structured and which forest plants they use will be important for assessing their prospects.
This article is based on reporting by Phys.org. Read the original article.
Originally published on phys.org
