Sooty Albatross - cryptic genetic and morphological difference between Atlantic and Indian Ocean birds

[Michael Szabo]

Cryptic variation in the sooty albatross Phoebetria fusca: genetic and morphological differences between Atlantic and Indian Ocean birds

Dilini K. Abeyrama1 · Michelle M. Risi2,3 · Maelle Connan4 · Peter G. Ryan2 · Christopher W. Jones2,3 · Trevor Glass5 ·
Alexis M. Osborne2,3 · Antje Steinfurth3 · Andy Schofield3 · Pierre Pistorius4 · Danielle Keys4 · Yves Cherel6 ·
Theresa M. Burg

Conservation Genetics (2025) 26:117–128
https://doi.org/10.1007/s10592-024-01656-0
Abstratct: The southern oceans are home to a large variety of organisms, including many endemic species. High levels of endemism
are due in part to non-physical barriers limiting gene flow in marine species. The sooty albatross Phoebetria fusca is
an endangered seabird breeding on seven island groups in Atlantic and Indian Oceans. We sequenced the mitochondrial
control region (55 birds) and genotyped 10 microsatellite markers (88 birds) to examine the population genetics of sooty
albatrosses from Tristan da Cunha and Gough Island (Atlantic Ocean), and Marion Island, Île de la Possession (Crozet)
and Amsterdam Island (Indian Ocean), which together support > 99% of the global population. We also analysed the bill
sulcus colouration and quantified stable isotope composition of body feathers of breeding adults from Gough and Marion
Islands. Both genetic markers identified two clusters separating sooty albatrosses breeding in the Atlantic and Indian
Ocean basins. Standardized colour analysis also separated populations in the two ocean basins and revealed the sulcus of
sooty albatrosses on Gough Island is significantly more yellow than individuals on Marion Island. Stable isotope analysis
of body feathers showed significantly higher δ13C values from Marion sooty albatrosses compared to Gough conspecif-
ics, indicating different moulting areas. Sooty albatrosses breeding on islands in the two ocean basins differ from each
other in their genetics, morphology and ecological preferences. Accordingly, it is recommended that separate conservation
management plans be implemented for sooty albatrosses breeding in each ocean basin to prevent the loss of evolutionarily
significant units.