Scientists have discovered a new species of penguins on the remote islands of the Indian Ocean
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- Scientists have discovered a new species of penguins on the remote islands of the Indian Ocean
Penguins living on the remote Kerguelen Islands in the southern Indian Ocean have been described by scientists as a separate species, Pygoscelis kerguelensis. Outwardly, these birds differ little from other Papuan penguins, but a comparison of genomes and physical characteristics has shown that they belong to an independent evolutionary lineage. The authors of the study also proposed to revise the classification of the entire group, identifying four species instead of one widespread one. About how the differences between birds arose and why the new classification is important for their protection, see the "Izvestia" material.
Why has the new species been noticed only now?
Papuan penguins, also called Gentoo penguins, live on the islands and coasts of the Southern Ocean. They have a dark back, white underparts, an orange beak, and a wide white stripe over their eyes. Populations from different parts of the range are so similar that for a long time they were attributed to the same species, Pygoscelis papua, although the question of the number of species and subspecies remained a matter of dispute.
The work was carried out by an international group of researchers from Chile, the USA and other countries. The authors of an article in the journal Communications Biology studied the genomes of 64 Papuan penguins from ten breeding colonies. The sample covered almost the entire range of the group. The scientists also compared the size and other structural features of the birds, data on their behavior, nutrition and breeding grounds.
"There is hardly another penguin whose classification would cause as much controversy as the Papuan one," said Rauri Bowie, one of the leaders of the study, a professor at the University of California at Berkeley.
According to him, scientists have been discussing for more than a hundred years how many individual species or subspecies belong to this group.
Which four types were suggested to be distinguished
The analysis confirmed the existence of four main evolutionary lines. The authors suggested that each one should be considered an independent species. The northern Papuan penguin retains the name Pygoscelis papua; its range, according to the new classification, is limited to the Falkland Islands (Malvinas) and Martillo Island off the coast of South America.
The southern species, Pygoscelis ellsworthi, inhabits the Antarctic Peninsula and other Antarctic regions, as well as South Georgia. The eastern one, Pygoscelis taeniata, is associated with the islands of Crozet, Marion and Macquarie. The fourth one, the southeastern one, Pygoscelis kerguelensis, was first described by the authors of the work as a separate species from the population of the Kerguelen Islands. The researchers also suggest its connection with the nearby Heard Island, but the genetic data in this part of the analysis were obtained from birds from Kerguelen.
The new scheme doesn't just assign different names to birds. It changes the idea of the size of the range of each species. A population that previously looked like part of a large species may turn out to be small and limited to several islands if assessed separately.
The authors also reviewed the status of South Georgia penguins. In previous work, these birds were described as a separate species Pygoscelis poncetii. The new study recognizes their noticeable differences, but refers them to the southern species as a subspecies of P. ellsworthi poncetii. Therefore, the thesis from the university report on "the first new penguin species in more than a hundred years" requires caution: the classification of this group has changed even before the current publication.
How the islands separated related populations
At first glance, the ocean should not be a serious obstacle for seabirds. However, Papuan penguins usually return to their familiar nesting sites and relatively rarely settle far from their colonies. They feed on fish, krill, squid, and other available prey, so they don't always need to travel far in search of food. Over time, the inhabitants of isolated islands became less likely to mix with other populations.
An additional boundary was the Antarctic Polar Front, an area of the Southern Ocean on different sides of which the properties of water, including temperature and salinity, differ markedly. Populations to the north and south of it existed in different conditions. Researchers attribute the gradual accumulation of genetic differences to geographical isolation and adaptation to the local environment.
Genomic analysis revealed signs of selection related to various body functions in different lineages. In southern birds, the researchers noted genes related to heat exchange, fat accumulation, and light perception. The eastern line focuses on oxygen use and metabolism; the northern line focuses on digestion and muscle function. These are genetic signs of possible adaptation, rather than a direct measurement of how much better each group tolerates the cold or dives.
What could happen by 2050
Scientists have modeled the change in marine conditions suitable for each line by 2050 under a moderate climate change scenario. They took into account the temperature and salinity of the water, its acidity and primary productivity, an indicator associated with the basis of marine food chains.
According to the basic model, suitable conditions can be significantly reduced for the northern, eastern and southeastern lines. For a new species from the Kerguelen Islands, the researchers admit the preservation of some of the suitable conditions in the Heard Island area. The forecast for southern penguins is different: the area of a suitable marine environment may increase by about 9%, primarily in the area of the Antarctic Peninsula.
This is not a forecast for the extinction of three species by 2050. The authors explicitly warn that the model takes into account a limited set of variables and is not able to fully predict how birds will change their diet, behavior, or habitats. The calculation option, taking into account the depth of the sea, gave a more favorable picture for some territories. The results show a possible reduction in suitable habitat, not that all islands will necessarily become uninhabitable for penguins.
Why change the classification for the sake of protecting penguins
If we consider all Papuan penguins as one species, the growth of a large southern population may hide the problems of others. According to the estimates given in the article, the southern line accounts for about 65% of the total number of the group, the northern — 24%, the southeastern - 9%, and the eastern — about 2%. The authors note that information on the number of island colonies is outdated and needs to be updated. (Communications Biology)
Separate recognition of species will make it possible to assess the condition of each group, taking into account its own range and threats. The researchers propose updating the counts of birds in colonies and conducting conservation assessments separately. This is especially important for the inhabitants of remote islands: if the conditions around their colony deteriorate, a suitable new location may be too far away.
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