Was penguin evolution driven by a cooling Antarctic?

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Penguins are a remarkable group of flightless birds. We tend to think of them as Antarctic birds, but they actually inhabit an extremely diverse range of habitats from subzero Antarctic coastline to the tropical Galapagos Islands. Research we published today in the Biology Letters gives us new insight into how this diverse group evolved.

There are now 18 recognised species of penguins. All live predominantly in the Southern Hemisphere (those Galapagos penguins being the exception), in a wide range of climates.

The habitats of modern penguins can be grouped into four climate zones. The Galapagos penguin (Spheniscus mendiculus) lives in a tropical habitat and two other species, the Peruvian penguin (S. humbolti) and the Black–footed (S. demersus) live in the subtropical regions.

Meanwhile Adélie, Chinstrap and Gentoo species (belonging to the genus Pygoscelis), the King and Emperor penguins (genus Aptenodytes) and Macaroni and Rockhopper penguins (both species of Eudyptes) are classic polar penguins, living in the Antarctic and sub-Antarctic.

The remaining eight species of penguins — the Fiordland, Snares, Erect-crested, Royal, Yellow-eyed, Magellanic, White-flippered and Little Blue penguin — live in temperate regions of the world.

Where penguins live can tell us something about how they are related. We can also look at fossils. Fossil penguins have been recovered from a range of latitudes in the Southern Hemisphere — from New Zealand to Peru.

 

 

 

Written By: Sankar Subramanian
continue to source article at theconversation.com

2 COMMENTS

  1. @OP link – Interestingly Antarctica saw rapid cooling around the same time — 10-15 million years ago. At this time Antarctica developed a permanent ice cap that covered the entire continent. We connected these two dots and speculate that there might be connection between the rapid cooling of the Antarctic and the divergence of the penguin lineages.

    The elimination of land predators by (those or earlier) advancing ice-sheets would look relevant to penguins’ larger size and flightless nature.

    In the northern hemisphere:-

    Auks are superficially similar to penguins having black-and-white colours, upright posture and some of their habits. Nevertheless they are not closely related to penguins, but rather are believed to be an example of moderate convergent evolution.

    Several species have different names in Europe and North America. The guillemots of Europe are murres in North America, if they occur in both continents, and the Little Auk becomes the Dovekie.

    Some species, such as the Uria guillemots, nest in large colonies on cliff edges; others, like the Cepphus guillemots, breed in small groups on rocky coasts; and the puffins, auklets and some murrelets nest in burrows. All species except the Brachyramphus murrelets are colonial.

    While some of the northern hemisphere examples of convergent evolution resemble penguins and seek isolated islands to nest, their greater exposure to predators has left them with the ability to fly in the air as well as using their wings underwater.

    http://commons.wikimedia.org/wiki/File:Puffin.jpg

    http://www.pbase.com/hankvv/image/137887452

  2. I have seen documentaries about the extremely inhospitable place penguins lay eggs. I gather the strategy is, the more inhospitable, the less likely any predator would hassle them. They might use an island without mammals, but can’t see such a clumsy bird making it on the mainland. Do they?

    I wondered if in some way that huge march they do started out short and was gradually stretched because of changing ice shelf width.

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