Adaptive Radiation

How the Naupakas Came to Be
Virginia Hayes
Each of the Hawaiian islands emerged from the sea as naked as any newborn. But
as soon as the lava cooled, visitors began arriving. For the very first islands these visitors
had to cross the wide Pacific Ocean. Some of the obvious early colonizers were birds
who could fly such distances. Insects, too, were swept across the sea to take refuge there.
Plants would become the next pioneers to appear. Some of their seeds could have stuck to
the feet of the birds. Others had seeds that could float for a while and be carried on the
currents and before the winds (often called drift seeds or drift fruits
[]). What all of these new inhabitants
found was that in this fresh lonely world, even as small as it was, there was plenty of
space to spread out since so few types of living things had made the long journey. As the
plants spread, some of them changed to adapt to different places on the island. Some
grew in the moist forests while others could live on the hot, dry slopes of the volcanoes.
The birds and other animals that eventually arrived, also adapted to different ways of
living and different food sources. This process is called adaptive radiation
Another process involved in adaptive radiation is known as speciation.
[] This evolution of many different
species from one founding father or mother happens everywhere, but on islands such as
the Hawaiian islands (and other isolated places like mountain tops), it produces unique
organisms that are found no where else on Earth. These plants, animals, and birds are
called endemic to the particular place that they live. One group of Hawaii’s distinctive
endemic plants is the silver sword alliance
[]. These daisy family relatives
apparently all evolved from a single California tarweed. Another example are the
naupakas (Scaevola species
There is a well-known Hawaiian legend [] that explains how the beach naupaka and the mountain
naupaka were created. Scientists now know that all the naupakas evolved from three
species that arrived on the islands from somewhere else.