Hawaiian Honeycreepers (Drepanidae)

    The Hawaiian honeycreepers provide another example of an adaptive radiation on an archipellago.  In Hawaii, at least until historical times, there were about 28 living species and 17 fossil species of birds in the family Drepanidae that pretty clearly have all evolved from a single ancestral species that colonized the Hawaiian islands some time in the past. These species show a great variety of morphologies and habits (see figure):  These species tend to be more cosmopolitan on the islands than the drosophilids, i.e. several of the species occur on more than one island.  However, 27 of the  45 living and fossil species inhabit(ed) just one island.  Moreover, 7 of the species inhabiting more than one island have different subspecies on different islands, indicating population divergence that is in process. This pattern is exactly what is expected from allopatric speciation on archipellagos, with the added realization that once a new species evolves it may occasionally colonize additional islands.
 

   The Hawaiian honeycreepers exhibit extensive diversification in bill shape and in the type of food that is eaten.  The family includes thin-billed species that feed on insects (e.g. Himatione sanguinea), long-billed species that feed on nectar (e.g. Drepanis funerea), thick-billed seed eaters (e.g. Psittirostra bailleui), and woodpecker-like species (e.g. Hemignathus wilsoni).  The arrows indicate inferred evolutionary transitions.  Not all species are portrayed.  (From D. J. Futuyma.  1998.  Evolutionary Biology.  Sinauer, Sunderland, MA.)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

             [ Back to Lecture 9 | Lecture Outlines | Bio 120 Home Page | Department of Biology | Duke University ]