During the Holocene colonization of islands in the Pacific and Caribbean by agropastoral and horticulturalist communities, a variety of proxies (material, genetic, zoogeographic etc.) indicate... Show moreDuring the Holocene colonization of islands in the Pacific and Caribbean by agropastoral and horticulturalist communities, a variety of proxies (material, genetic, zoogeographic etc.) indicate substantial inter-island and inter-community contact. It has been suggested that this contact represents an adaptive response to mitigate intrinsic demographic fragility during the initial phases of island colonization, and that this exogamous imperative faded in the aftermath of initial dispersal as overall population density increased. Here, we evaluate this model by synthesizing and comparing increasingly available 87Sr/86Sr data from funerary populations in the Pacific and Caribbean. After performing basic hygienic discrimination, we conclude that the Caribbean data—both from across the region, and on an intra-site/island basis—lend support to this model, with high early in-migration succeeded by comparatively low in-migration in a relationship which, based on chi-square tests, is statistically significant (1, N = 290) = 4.046, p = 0.044). The Pacific situation is more complex, with data from the Bismarck Archipelago and northern Solomon Islands skewing the analysis. However, in considering these data in detail, we demonstrate that there are reasons to suppose that the Pacific data may also tentatively support a model of high rates of in-migration being replaced later in settlement histories by comparatively low rates. We conclude by highlighting future directions for this incipient research program. Show less
This thesis deals with the associations between parasitic snails and their mushroom coral hosts. Gittenberger has spent 800 hours under water and searched about 60,000 coral discs for these... Show moreThis thesis deals with the associations between parasitic snails and their mushroom coral hosts. Gittenberger has spent 800 hours under water and searched about 60,000 coral discs for these parasites. He dived in Egypt, the Maldives, Thailand, Malaysia, Japan, Palau, the Philippines, Indonesia and Australia. Places that are less popular with divers, like very deep or shallow sites, areas with strong currents, murky water, or sandy bottoms, received special attention. The greatest biodiversity was found off Sulawesi, a region that needs protection. Except for shell morphology, molecular, anatomical and ecological characters of the snails were studied. As a result it turned out that many more species exist than hitherto thought. Some dozens of unnamed cryptic ones were discovered. These can be distinguished most clearly by their DNA and their host specificity. The species of parasitic snails evolved most probably by bypassing the defence mechanism of one or a few coral species. Most of the data support a sympatric speciation model for these taxa. The molecular phylogenies of the parasites and their hosts were compared to investigate the amount of co-evolution. Show less
