For numerous decades, the scientific community classified the yellow-eyed penguin (Megadyptes antipodes) as a singular species, broadly categorized into two distinct populations. However, a recent comprehensive genomic investigation has dramatically altered this perception, unveiling three profoundly divergent lineages that have been reproductively isolated for millennia—a timeframe significantly predating the human settlement of New Zealand (Aotearoa).
Geographical distribution of yellow-eyed penguins. Image credit: Guhlin et al., doi: 10.1038/s41559-026-03062-w.
Initially documented by Jacques Bernard Hombron and Honoré Jacquinot in 1841, yellow-eyed penguins are a critically endangered avian species indigenous to New Zealand.
These birds are held in high esteem as taonga (precious treasures) by the Māori, the Indigenous inhabitants of New Zealand, who refer to them by the names hoiho or takaraka.
Commencing in 2019, a lethal neonatal ailment, specifically respiratory distress syndrome, has adversely affected chicks on the New Zealand mainland, contributing to a precipitous drop in breeding pairs to fewer than 115.
“As one of the world’s most infrequently encountered penguin species, yellow-eyed penguins serve as a pivotal indicator of ecological vitality, with their population trends mirroring broader environmental shifts,” stated senior author Professor Jemma Geoghegan from the University of Otago, alongside her colleagues.
“Consequently, the preservation of yellow-eyed penguins is paramount for safeguarding biodiversity and maintaining the structural integrity of coastal ecosystems.”
“Furthermore, they represent an iconic element of the regional wildlife tourism sector, providing substantial economic benefits to local communities.”
“Therefore, their diminishing numbers signify a significant biodiversity crisis, coupled with a loss of cultural and economic value.”
In the course of the recent investigation, Professor Geoghegan and her collaborators conducted whole-genome sequencing on 249 yellow-eyed penguins sourced from the New Zealand mainland (representing the northern range) and the sub-Antarctic islands of Enderby (Auckland Islands) and Campbell Island (southern range).
Their initial expectation was to corroborate a straightforward dual-population structure. The discoveries, however, proved to be far more remarkable.
Employing a sophisticated array of advanced genomic methodologies, the research team identified three genetically distinct groups exhibiting virtually no gene flow between them.
The magnitude of their genetic divergence, the researchers concluded, substantiates the formal recognition of each group as a distinct subspecies.
“Within this study, we leveraged population genomics to scrutinize the evolutionary trajectory and susceptibility to disease among the endangered yellow-eyed penguin/hoiho, one of the planet’s most scarce penguin species,” Professor Geoghegan elaborated.
“Underwritten by Genomics Aotearoa, we generated complete genome data from 249 penguins across the entirety of mainland New Zealand and its subantarctic islands to gain a deeper understanding of the factors contributing to the mortality of mainland population chicks due to a severe respiratory ailment known as respiratory distress syndrome.”
“To our surprise, our findings indicated that hoiho comprise three deeply separated subspecies with no observable inter-population migration.”
“Our analytical results suggest that these populations have been geographically isolated for thousands of years, a duration significantly longer than previously hypothesized.”
“This implies that the critically endangered northern population is not merely a recent outgrowth of the southern populations but constitutes a unique evolutionary lineage in its own right.”
“We have identified candidate genes associated with immune function and respiratory physiology that may offer explanations for the northern population’s apparent singular vulnerability to respiratory distress syndrome.”
“These revelations furnish novel insights into the role of host genetics in wildlife pathology and carry substantial implications for conservation strategies.”
Following extensive consultations with Ngāi Tahu, the predominant iwi (tribe) of New Zealand’s South Island, who serve as kaitiaki (guardians) for this species, the study’s authors proposed new subspecies designations derived from Māori geographical terminology: Megadyptes antipodes murihiku (hoiho murihiku) for the northern population, Megadyptes antipodes motu maha (hoiho motu maha) for Enderby Island within the Auckland Islands archipelago, and Megadyptes antipodes motu ihupuku (hoiho motu ihupuku) for Campbell Island.
“Collaborating in partnership with Ngāi Tahu, the esteemed kaitiaki of hoiho, we aspire for this research to facilitate immediate and targeted conservation interventions for each distinct subspecies, with particular emphasis on the rapidly dwindling northern lineage, which presently comprises fewer than 115 breeding pairs,” stated Professor Geoghegan.
The research team’s publication has been officially released in the esteemed journal Nature Ecology & Evolution.
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J. Guhlin et al. Population genomics of yellow-eyed penguins uncovers subspecies divergence and candidate genes linked to respiratory distress syndrome. Nat Ecol Evol, published online May 12, 2026; doi: 10.1038/s41559-026-03062-w
