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Aim The diversity and composition of species pools within oceanic archipelagos is determined by a combination of colonization, abiotic tolerance, in situ diversification, biotic interactions and extinction. The signature of biogeographic events and evolutionary processes, however, may be masked by recent coalescence and hybridization between closely related species. We used the species-rich plant genus Cyrtandra (Gesneriaceae) to investigate the roles of colonization and hybridization in shaping community assemblages on the geologically young Hawai'i Island. Location Hawaiian Islands. Taxon Cyrtandra (Gesneriaceae). Methods We sampled 29 Cyrtandra taxa and putative hybrids across the main Hawaiian Islands and generated single nucleotide polymorphisms (SNPs) from nine single-copy nuclear genes. Maximum likelihood and Bayesian inference were used to reconstruct phylogenetic relationships, divergence times were estimated using secondary calibrations and island ages, and ancestral area estimation was done using likelihood models. Lastly, we used a Bayesian population assignment test and principal components analysis to infer population genetic structure. Results Cyrtandra colonization of the main Hawaiian Islands appears to have followed the progression rule, whereby the oldest high Hawaiian Islands (Kaua'i and O'ahu) were colonized first, followed by colonization of the younger islands as habitat became available. Hawai'i Island was colonized four times, with two dispersal events from O'ahu and two from Maui Nui. The different colonization events gave rise to significantly uneven numbers of species, and hybridization among the incipient lineages was detected in the form of intermediate genotypes. Main conclusions Our investigation into community assembly in a species-rich plant genus on a geologically young oceanic island revealed a history of multiple colonizations and hybridization among colonizing lineages. The rapid diversification (3.5 species/My) of one of four Cyrtandra lineages on Hawai'i Island may be the result of hybridization between genetically diverse lineages that stem from independent colonization events. Multiple colonization events followed by a merging of lineages may be particularly common during early-stage community assembly on islands and, through the generation of genetic variation, may be especially important for species diversification.

Island archaeology is a well-established field within the wider discipline, but African contributions to it remain scarce. The Canary Islands are unusual in the broader African context for their relatively long history of occupation (~2000 years) and the intensity with which archaeological research has been, and is, undertaken there. Much of that research, however, has focused on specifically Canarian issues, including efforts to demonstrate connections between the islands’ initial settlement and the Classical Mediterranean world. Relatively little of it has been conducted within the broader comparative framework that an island archaeology perspective provides. Additionally, much of the Canarian literature is not directly accessible to non-Hispanophones. In response, I synthesize what is currently known about the archaeology of the Canary Islands, focusing on determining when, how, and by whom they were first settled; the impacts of human settlement on their environments; inter-island variability in precolonial subsistence, social, and political trajectories; and the record left by European contact and subsequent colonization, which began in the 14th century AD. As well as pointing to further opportunities for research within the archipelago, I simultaneously map out several areas where archaeological work there could contribute to wider debates in island archaeology as a whole.

Aim The use of intuitive or explicit biogeographical reconstruction techniques to estimate the timing of species radiations on the Hawaiian Islands, while often incorporating evidence on the timing of island formation, may be misleading if the effects of extinction are overlooked. Using phylogenies of the bark louse genus Ptycta (Psocidae), we compared results from biogeographical character mapping with those from molecular dating analyses. These results were used to evaluate the 'progression model', which predicts an oldest-to-youngest pattern of island colonization. Location The main Hawaiian Islands (Kauai, Oahu, Maui, Lanai, Molokai and Hawaii). Methods With a data set including 101 Hawaiian Ptycta specimens and 18 outgroup species, we constructed molecular phylogenies based on sequences of the nuclear gene wingless and mitochondrial genes 12S, 16S and cytochrome c oxidase subunit I (COI). Maximum-likelihood, maximum-parsimony and Bayesian phylogenetic analyses were used. We used BEAST to estimate a time-calibrated tree under a relaxed clock model. Results Our analyses suggested a single colonization event, followed by extensive movement of Ptycta among islands and species radiations within and between islands. This monophyletic radiation is composed of two well-supported clades that are also supported by two synapomorphic characters of the male genitalia. Main conclusions Very different biogeographical patterns are inferred by molecular dating versus approaches based on character mapping. Simple biogeographical reconstruction over the molecular phylogeny supports a pattern of youngest-to-oldest island colonization, the reverse of that predicted by the 'progression model', and implies that this radiation could be as young as the most recent islands of Maui (1.4 Ma) or Hawaii (0.5 Ma). Molecular dating, however, infers a pattern consistent with oldest-to-youngest island colonization, and suggests a lineage age of 7.1 Ma. Extinction on the oldest island of Kauai may account for the differences in results between the two analyses.