Ornithocoprophilous Endemism in Pacific Basin Angiosperms

Evidence is presented for the existence of genetically distinct races or taxa of angiosperms which are restricted to deposits of seabird guana occurring on islands in the Pacific basin. Various lines of evidence suggest that these ornithocoprophilous plants can be considered somewhat weedy nitrophilous halophytes. Many of the morphological characters by which they are distinguished from their nearest non—coprophilous relatives seem to be adaptively related to the unusual nature of their habitat. Other not obviously adaptive characters may have become fixed by genetic drift in these small populations. A possible mode of origin of guano endemism is proposed.