Scientists decipher iconic Helmeted Honeyeater genome, paving way for genetic rescue operations

In a major milestone towards rescuing the critically endangered Helmeted Honeyeater, a team led by biologists from Monash University have deciphered the bird's genome. The genome sequence and other genetic information collected are published in a study today in GigaScience. The findings are a boost for genetic rescue efforts for the Helmeted Honeyeater subspecies, which is the emblem bird of the Australian State of Victoria. The number of Helmeted Honeyeaters has significantly declined over the 200 years since non-Indigenous people arrived in Australia. By the 1980s only around 50 birds were left at a single location, at Yellingbo Nature Conservation Reserve. Ongoing conservation efforts include habitat restoration and a captive breeding program, and there are now approximately 250 birds. However, these activities may not be enough to secure a long-term future for the Helmeted Honeyeater. Due to the small number of remaining individuals, all belonging to the same population, many mating events in the wild occur between birds that are genetically closely related. In addition to causing harm by inbreeding, small population size tends to lead to the accumulation of detrimental mutations. However, 'genetic rescue'—the introduction of genes from outside the small gene pool of the endangered population—can provide a solution to restoring the genetic health of wildlife populations. "Because the Helmeted Honeyeater is the last of its kind, genetic augmentation must come from a different subspecies," said study author Dr Alexandra Pavlova, from the Monash University School of Biological Sciences. "However, this kind of genetic mixing is not common: conservation managers generally avoid crossing subspecies for fear of losing local adaptation and distinctiveness." The new high-quality genome sequence and associated genetic tools will be of tremendous help to guide the process of 'mixing in' DNA from outside the current gene pool. In particular, the research team presents the first chromosome length genome sequence for the species - that is, the data quality is so high that the assembled sequences of genetic 'letters' span full chromosomes. They also produced a high-density genetic map, including more than 50,000 marker positions. "The genome sequence and the genetic map will be used to get the right balance between rescuing the helmeted honeyeater from extinction through inbreeding, while retaining unique features that make it a helmeted honeyeater," said lead author Dr Diana Robledo-Ruiz, also from the School of Biological Sciences. With the exceptional genomic resources now available, a new chapter for rescuing the Helmeted Honeyeater begins. But without the passion, commitment, and work of hundreds of people and many organisations, the Helmeted Honeyeater would already be extinct. "This support includes Victoria's Department of Environment, Land, Water and Planning (DELWP), Zoos Victoria and the Helmeted Honeyeater Recovery Team," said study co-author Professor Paul Sunnucks, also from the School of Biological Sciences. "Some individuals such as Bruce Quin of DELWP have devoted 30 years or more to conservation efforts of the species, and a highly effective community group, The Friends of the Helmeted Honeyeater, has provided a range of assistance for the conservation program for more than three decades," he said. "It is an inspiring case of people caring and making a real difference to biodiversity outcomes."