Morphological Assortment and the Assembly of Communities of Introduced Passeriforms on Oceanic Islands: Tahiti Versus Oahu

Abstract

We conducted an ecomorphological analysis on the introduced passeriforms of Ta- hiti and tested for community patterns reported for the introduced passeriforms of Oahu, Hawaii. Although the island of Tahiti is similar to Oahu in size, distance from the equator, and number of passeriform introductions, the two islands differ greatly in rates of introduction success: on Oahu 27 of 43 (63%) introductions have been successful, whereas on Tahiti only 7 of 41 (17%) have been successful. Possible explanations for this difference include unfavorable environmen- tal conditions, differences in the timing of the introductions, differences in the taxonomic diver- sity of the sets of introduced species, and differences in habitat diversity between the islands. Despite the difference in rates of introduction success, the same pattern of morphological over- dispersion seen on Oahu also occurs on Tahiti. The pattern of morphological overdispersion is consistent with the hypothesis that interspecific competition has influenced the assembly of this community.