The islands of French Polynesia cover an area the size of Europe, though total land area is smaller than Rhode Island. Each hot spot archipelago (Societies, Marquesas, Australs) is chronologically arranged. With the advent of molecular techniques, relatively precise estimations of timing and source of colonization have become feasible. We compile data for the region, first examining colonization (some lineages dispersed from the west, others from the east). Within archipelagos, blackflies ( Simulium ) provide the best example of adaptive radiation in the Societies, though a similar radiation occurs in weevils ( Rhyncogonus ). Both lineages indicate that Tahiti hosts the highest diversity. The more remote Marquesas show clear examples of adaptive radiation in birds, arthropods and snails. The Austral Islands, though generally depauperate, host astonishing diversity on the single island of Rapa, while lineages on other islands are generally widespread but with large genetic distances between islands. More recent human colonization has changed the face of Polynesian biogeography. Molecular markers highlight the rapidity of Polynesian human (plus commensal) migrations and the importance of admixture from other populations during the period of prehistoric human voyages. However, recent increase in traffic has brought many new, invasive species to the region, with the future of the indigenous biota uncertain.

Dispersal plays a key role in shaping biological and ecological processes such as the distribution of spatially-structured populations or the pace and scale of invasion. Here we have studied the relationship between long-distance dispersal behaviour of a pest-controlling money spider, Erigone atra, and the distribution of maternally acquired endosymbionts within the wider meta-population. This spider persists in heterogeneous environments because of its ability to recolonise areas through active long-distance airborne dispersal using silk as a sail, in a process termed 'ballooning'. We show that there is spatial heterogeneity in the prevalence of two maternally acquired endosymbiont infections within the wider E. atra meta-population and we demonstrate through several independent approaches a link between the presence of one of these endosymbionts, Rickettsia, and the tendency for long-distance movement. This novel finding that particular endosymbionts can influence host dispersal is of broad importance given the extremely widespread occurrence of similar bacteria within arthropod communities. A bacterial phenotype that limits dispersal has the potential not only to reduce gene flow and thus contribute to degrees of reproductive isolation within species, but also to influence species distribution and thus overall community composition.

Adaptive radiation of partulid land snails in the tropical Pacific has produced an extraordinary array of distinctive morphological, ecological and behavioural types. Here we use part of the nuclear ribosomal RNA gene cluster to investigate the relationships within and between the three partulid genera, Partula, Samoana and Eua. The genera cluster separately, with Samoana and Partula forming monophyletic groups. With one exception, the molecular data generally support the previous generic classification based on genital morphology, even in species that show a number of characteristics otherwise atypical of the genus. Convergent evolution explains morphological similarities between members of different genera. The phylogeny suggests that Samoana has colonized the Pacific from west to east, originating in the area where Eua, believed to be the most ancient partulid genus, is found. An unexplained anomaly is the reported occurrence of a single species of Samoana in the Mariana Islands of the western Pacific. The genus Partula has a disjunct distribution, encompassing islands both to the east and west of the range occupied by Eua. Partula seems to have spread both eastward and westward after the splitting of the Partula lineage.