Hawai not an evolutionary dead end for marine life
London: Marine species were thought to colonize Hawaii and eventually diverge into an isolated native species, but were doomed to an evolutionary “dead end” with no further specialization and speciation.
However, Dr. Chris Bird and fellow researchers at the Hawaii Institute of Marine Biology (HIMB) have shown that Hawaii hosts three limpets (cone shaped marine snails, locally known as ‘opihi’) that defy classification as dead-enders.
The standard explanation for three species of ''opihi is that Hawaii was independently colonized three times. However, using DNA, fossil and geologic evidence, Bird has shown that Hawaii was successfully colonized only once by Japanese limpets, approximately 5 million years ago.
The opihi then speciated within the Hawaiian Archipelago along an ecological gradient, as they invaded deeper habitats, forming the three species that we observe today (in order from shallow to deep) ''opihi makai''auli, ''opihi ''alinalina, ''opihi ko''ele.
Bird proposes that differences in the timing of sperm and egg production and the ability to survive at particular shore levels led to the ''opihi radiation.
While ''opihi may look similar to the untrained eye, Bird demonstrates that each species possesses novel evolutionary adaptations that confer an advantage at a particular shore level, a hallmark signature of natural selection and adaptive radiation.
Prior to this report, no marine radiations had been found in Hawaii.
Bird’s findings concluded that Hawaii is not an evolutionary dead end for marine speciation.