Adaptive radiation is well known on remote islands. Species proliferate in these isolated environments to fill the available ecological space. In this paper I examine the role of random versus deterministic processes in the evolution of communities on the remote islands of Polynesia. How predictable is the process of species formation, and how similar are the communities that arise in parallel environments on different islands? I first examine this question for the Hawaiian Islands. Phylogenetic analysis, using information from morphology, ecology, and molecular sequences, coupled with the relative ages of the islands, was used to examine convergence of ecological equivalents among endemic lineages of spiders (genus Tetragnatha) that have diversified within the archipelago. The results indicate that similar sets of "ecomorphs" have evolved largely independently on each island. I have recently expanded the research to consider two additional hot-spot oceanic archipelagoes in southern Polynesia: The Marquesas, and Society Islands. Comparing the different archipelagoes, the data suggest that adaptive radiation of the same genus Tetragnatha has occurred, although to a lesser extent, in the Marquesas and Society archipelagoes, and the nature of the adaptive changes is strikingly similar to what has occurred in Hawaii. However, the lineages in each archipelago are unrelated. The conservation concerns arising from alien invasion are similar in each of the archipelagoes. However, unlike the native communities, the species composition of alien spiders has little in common between the different island groups.
Keywords: Hawaiian spiders
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA