Regent honeyeaters maintain genetic diversity in face of massive habitat threat

Regent honeyeaters, endemic to southeastern Australia, are keeping their genetic diversity despite population collapse over the past century, according to new research.

The study is published in the Proceedings of the Royal Society B: Biological Sciences.

Regent honeyeaters (Anthochaera Phrygia) are listed as critically endangered on the IUCN Red List of Threatened Species.

“The species has declined from hundreds of thousands of individuals to fewer than 300 over the past 100 years,” the authors write. This rapid population crash is the result of habitat destruction due to agriculture and development, invasive species and habitat alteration due to climate change.

Going further back, the researchers’ modelling shows a steady population decline 2,000–2,500 years ago. But this sharply accelerated within the past 500 years.

The new study sought to understand the impact of the regent honeyeater’s population collapse on the species’ genetic health. The team sequenced and compared whole genomes of 20 modern birds with 24 museum specimens which lived before 1919.

Specimens covered much of the regent honeyeater’s geographical distribution in Australia from Queensland in the north to Victoria in the south.

“Despite this substantial demographic collapse, the regent honeyeater has lost only 9% of its genetic diversity, with no evidence of inbreeding or connectivity loss,” the authors write.

In fact, the regent honeyeater has higher diversity than many other threatened bird species, the authors note.

Genetic diversity is critical for species to be able to adapt to environmental changes and pressures.

Future projections of how the species’ genome will change suggests that the lag between population decline and genetic diversity loss could be hiding future risk of genetic collapse as environmental suitability continues to degrade.

“While the current genetic diversity appears stable, the long-term consequences of genetic diversity loss and potential future inbreeding due to further declines should not be underestimated,” the authors write.

They stress the importance of targeted conservation efforts.

“Conservation strategies should aim to preserve genetic diversity and prevent inbreeding through habitat connectivity and, if necessary, genetic rescue efforts.”