Abstract
BackgroundPenguins are flightless aquatic birds widely distributed in the Southern Hemisphere. The distinctive morphological and physiological features of penguins allow them to live an aquatic life, and some of them have successfully adapted to the hostile environments in Antarctica. To study the phylogenetic and population history of penguins and the molecular basis of their adaptations to Antarctica, we sequenced the genomes of the two Antarctic dwelling penguin species, the Adélie penguin [Pygoscelis adeliae] and emperor penguin [Aptenodytes forsteri].ResultsPhylogenetic dating suggests that early penguins arose ~60 million years ago, coinciding with a period of global warming. Analysis of effective population sizes reveals that the two penguin species experienced population expansions from ~1 million years ago to ~100 thousand years ago, but responded differently to the climatic cooling of the last glacial period. Comparative genomic analyses with other available avian genomes identified molecular changes in genes related to epidermal structure, phototransduction, lipid metabolism, and forelimb morphology.ConclusionsOur sequencing and initial analyses of the first two penguin genomes provide insights into the timing of penguin origin, fluctuations in effective population sizes of the two penguin species over the past 10 million years, and the potential associations between these biological patterns and global climate change. The molecular changes compared with other avian genomes reflect both shared and diverse adaptations of the two penguin species to the Antarctic environment.Electronic supplementary materialThe online version of this article (doi:10.1186/2047-217X-3-27) contains supplementary material, which is available to authorized users.
Highlights
Penguins are flightless aquatic birds widely distributed in the Southern Hemisphere
In the four subfamilies of β-keratin genes [39], we found that the numbers of keratinocyte β-keratin genes in the Adélie and emperor penguins are among the highest of all avian species (Figure 2A: emperor, 15; Adélie, 13) and only two other birds have ≥13 keratinocyte β-keratin genes (Pekin duck Anas platyrhynchos, 14; killdeer Charadrius vociferus, 13)
By comparing the genomes of 48 avian species, we found that most birds had four classes of cone opsin genes, while Adélie and emperor penguins
Summary
Penguins are flightless aquatic birds widely distributed in the Southern Hemisphere. The distinctive morphological and physiological features of penguins allow them to live an aquatic life, and some of them have successfully adapted to the hostile environments in Antarctica. Sphenisciformes (penguins), an avian order comprising six extant genera and 18 species [1], are flightless aquatic birds widely distributed in the Southern Hemisphere. The penguins living in Antarctica are subject to extremely low temperatures, high winds, and profound seasonal changes in the length of daylight [13]. To live in such a harsh environment, penguins have developed a complicated system in the head, wing, and legs for enhanced thermoregulation [14,15], and an effective management of energy storage for long-term fasting [16,17,18]. Because of their important roles in the Antarctic ecosystem and their sensitive responses to changes in marine and Antarctic climate, penguins are among the widely studied organisms in climate change research [19,20,21,22]
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