Scientists from Monash University and elsewhere have sequenced and assembled the nuclear and mitochondrial genomes of the helmeted honeyeater (Lichenostomus melanops cassidix), an emblem of the Australian state of Victoria.
The helmeted honeyeater is a small woodland bird in the superfamily Meliphagoidea.
Distinguished by its characteristic helmet of crown feathers, it is one of four subspecies of the yellow-tufted honeyeater (Lichenostomus melanops).
Endemic to the state of Victoria, Australia, the helmeted honeyeater was declared Victoria’s bird emblem in 1971.
It has been classified as Critically Endangered, and its sole population consists of just 250 individuals inhabiting the Yellingbo Nature Conservation Reserve.
The helmeted honeyeater has been subject to intensive conservation management, including captive breeding.
Despite this, the species population exhibits a small effective size, low genetic variation, and strong inbreeding depression.
To increase the genetic health of the helmeted honeyeater, Monash University researcher Alexandra Pavlova and her colleagues are working together to create a genetic rescue program by introducing genes from a subspecies outside the small gene pool of the endangered population.
“Because the helmeted honeyeater is the last of its kind, genetic augmentation must come from a different subspecies,” Dr. Pavlova said.
“However, this kind of genetic mixing is not common: conservation managers generally avoid crossing subspecies for fear of losing local adaptation and distinctiveness.”
“These issues can now potentially be avoided given the availability of the bird’s first chromosome-length genome sequence — that is, the quality of the data is so high that the assembled sequences of the genetic ‘letters’ cover entire chromosomes rather than the more commonly available genome sequences that are less complete and continuous.”
In addition, the researchers also produced a high-density genetic map, which includes more than 50,000 marker positions.
A genetic map with this many markers allows the scientists to follow exactly which part of every chromosome in an individual was inherited from each parent.
“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 Dr. Diana Robledo-Ruiz, a researcher at Monash University.
“Having such exceptional genomic resources now available begins a new chapter for rescuing the helmeted honeyeater.”
“However, without the passion, commitment, and work of hundreds of people and many organizations, the helmeted honeyeater would already be extinct.”
The results appear in the journal GigaScience.
Diana A. Robledo-Ruiz et al. 2022. Chromosome-length genome assembly and linkage map of a critically endangered Australian bird: the helmeted honeyeater. GigaScience 11: giac025; doi: 10.1093/gigascience/giac025
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