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An
emperor penguin on the Ross Ice Shelf.
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Adaptation
Treasure Trove
There is no shortage of examples of clever adaptations
to Antarctica’s hostile environment. To protect against
the cold, penguins have adapted short overlapping feathers,
rounded bodies, and fat storage under the skin. Antarctica’s
only two flowering plants, Antarctic grass and Antarctic
pearlwort, have evolved structural changes as defense
against severe ultraviolet radiation from the sun. Some
Antarctic algae photosynthesize at –7°C, exceeding
the photosynthetic
capability
of algae from temperate regions.
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Nature
boasts many other instances of adaptive radiation. It occurs
when birds, insects, and other species colonize new islands
made by volcanoes. The mass extinction of the dinosaurs paved
the way for an adaptive radiation: mammals diversified into
many new species with special adaptations for running, swimming,
climbing, and other types of motion.
History
Hinges on the Itsy-Bitsy
The history of the Notothenioids’ rise to fame in Antarctica
reveals a central characteristic of evolution: One small change
can dramatically alter history. For the Notothenioids, one
adaptation—the development of the antifreeze gene—paved
the way for a multitude of other adaptations and new species.
Like these hardy fish, each species on Earth today arose from
other species through a chain of adaptations, one change making
the next one possible.
It’s
intriguing to ponder what the Antarctic marine ecosystem would
look like today if that tiny DNA mutation in one ancestor
had never happened.
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