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Genetic analysis ends 20 years of debate over whether the Amsterdam albatross is separate species

By Helen Roddis - 21 Mar 2011 20:24:0 GMT
Genetic analysis ends 20 years of debate over whether the Amsterdam albatross is separate species

Image Credit: Vincent Legendre

Whether or not the Amsterdam albatross (Diomedea amsterdamensis) should be considered a separate species has long been a topic of debate in the scientific community.

Now, Dr Theresa Burg and researchers from the University of Lethbridge, Canada, have put paid to the conversation, with genetic analysis confirming that the world's rarest albatross is indeed a separate species.

The Amsterdam albatross is classified as Critically Endangered on the IUCN Red List. It is an extremely large albatross that breeds only on Amsterdam Island in the southern Indian Ocean, where its total population is made up of just 130 individuals. The Amsterdam albatross's breeding range is restricted further still, to a single area of the island known as the Plateau des Tourbieres.

First discovered in 1983, the Amsterdam albatross was considered to be a subspecies of the wandering albatross (Diomedea exulans).

However, the Amsterdam albatross differs in appearance from the wandering albatross, being slightly smaller and having distinctly browner plumage. They also lay their eggs at different times.

The Canadian researchers set out to resolve the debate, examining the levels of variation in the highly variable mitochondrial control regionof the birds' DNA to determine whether the albatrosses breeding on Amsterdam Island form a genetically distinct group.

The researchers discovered that the DNA of the Amsterdam albatross does vary significantly from wandering albatrosses. They also showed that it is highly likely that the Amsterdam albatross became a genetically distinct species up to 265,000 years ago.

The DNA results indicate that the albatrosses on Amsterdam Island should be considereda distinct, evolutionarily important population.

Dr Burg and her team suggest that the geographical isolation of the Amsterdam albatross is what led the birds to evolve into a separate species.

Scientists hope that now this Critically Endangered albatross has been recognised as a unique and distinct species, conservation efforts will increase.

Although numbers of the Amsterdam albatross actually increased in recent years, the species only breeds every other year and as few as 18 to 25 pairs breed annually on the island.

The species' survival is threatened by accidental entanglement in long-line fishing gear and nest-site disturbance by introduced predators and domestic animals. Disease is also an emerging concern, especially given the extremely low levels of genetic variation within the population.

The findings are published in the Journal of Avian Biology.