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The approximately 320 atolls of the world, scattered across the tropical oceanic basins, constitute a unique type of ecosystem in that they are each an integrated unit consisting of island, coral reef, and lagoon components. Atolls have a complex geology, ecology, and biogeography, which can be fully appreciated only by transcending the classic boundary thinking of marine and terrestrial realms. The atolls we observe today were shaped by Quaternary sea-level fluctuations, which imposed strong environmental filters on their communities. As entirely biogenic, reef-borne structures, the islands of atolls depend upon marine productivity, which catalyzes island community assembly. Island species communities exist in complex dynamic equilibria with the surrounding oceanographic conditions. Energy fluxes and element cycles of the atoll system readily cross habitat boundaries and create a productive, diverse, and biomass-rich ecosystem on land and underwater. Past human disturbances and future global change put atolls at the forefront of conservation and ecological restoration. [ABSTRACT FROM AUTHOR]

DNA barcoding has been largely successful in differentiating animal species, but the most effective loci and evaluative methods for plants are still debated. Floras of young, oceanic islands are a challenging test of DNA barcodes, because of rapid speciation, high incidence of hybridization and polyploidy. We used character-based, tree-based and genetic distance-based methods to test DNA barcoding of 385 species of native Hawaiian plants constituting 20 lineages at the nuclear ITS(2) locus, nine lineages at each of the plastid loci trnH-psbA and rbcL , eight lineages at the plastid locus matK and four lineages with concatenated data. We also incorporated geographical range information and tested if varying sample sizes within a lineage influenced identification success. Average discrimination success was low (22% maximum) with all methods of analysis across all loci. The character-based method generally provided the highest identification success, there were limited benefits from incorporating geographical data and no relationship between number of species sampled in a lineage and identification success was found. Percentages of identification success are the lowest reported in a DNA barcoding study of comparable scale, and multi-species groups that radiated in the Hawaiian archipelago probably cannot be identified based on current DNA barcoding loci and methodologies. [ABSTRACT FROM AUTHOR]

Aims The 50th anniversary of the publication of the seminal book, The Theory of Island Biogeography, by Robert H. MacArthur and Edward O. Wilson, is a timely moment to review and identify key research foci that could advance island biology. Here, we take a collaborative horizon-scanning approach to identify 50 fundamental questions for the continued development of the field. Location Worldwide. Methods We adapted a well-established methodology of horizon scanning to identify priority research questions in island biology, and initiated it during the Island Biology 2016 conference held in the Azores. A multidisciplinary working group prepared an initial pool of 187 questions. A series of online surveys was then used to refine a list of the 50 top priority questions. The final shortlist was restricted to questions with a broad conceptual scope, and which should be answerable through achievable research approaches. Results Questions were structured around four broad and partially overlapping island topics, including: (Macro)Ecology and Biogeography, (Macro)Evolution, Community Ecology, and Conservation and Management. These topics were then subdivided according to the following subject areas: global diversity patterns (five questions in total); island ontogeny and past climate change (4); island rules and syndromes (3); island biogeography theory (4); immigration-speciation-extinction dynamics (5); speciation and diversification (4); dispersal and colonization (3); community assembly (6); biotic interactions (2); global change (5); conservation and management policies (5); and invasive alien species (4). Main conclusions Collectively, this cross-disciplinary set of topics covering the 50 fundamental questions has the potential to stimulate and guide future research in island biology. By covering fields ranging from biogeography, community ecology and evolution to global change, this horizon scan may help to foster the formation of interdisciplinary research networks, enhancing joint efforts to better understand the past, present and future of island biotas. [ABSTRACT FROM AUTHOR]

We investigated whether the plants of the Galápagos Archipelago and Cocos Island, which are each other's closest neighboring insular systems, show any such sister relationships. Five genera of vascular plants have endemics in both archipelagos, including plants with different life histories and dispersal mechanisms: tree ferns, epiphytes, trees, herbs, and shrubs, with adaptations for dispersal by wind or birds (two genera each) or with no obvious dispersal adaptation (one genus). We obtained molecular phylogenies for these genera to test the hypothesis of phytogeographical links between the islands. The phylogenies for all five genera were not consistent with this hypothesis, but they supported floristic studies in revealing no direct phytogeographical links between the islands. We attribute this lack of floristic affinity primarily to air and ocean circulation patterns that limit dispersal between Galápagos and Cocos and to a low frequency of interisland bird movements. There are also major ecological differences between them, and Cocos Island is quite small, which limits the chance of random dispersal events and subsequent establishment. [ABSTRACT FROM AUTHOR]