Some genetic traits in Solomon island populations. I. Introduction: people and habitats

To introduce a set of genetic studies among Solomon Islanders, four tribal groups on Bougainville and Malaita Islands are described. They were observed in 1966 and 1968 by social anthropologists and biomedical scientists from Harvard University. The groups varied in habitat and way of life from fishermen living on artificial islets in a saltwater lagoon (the Lau, on Malaita) to shifting agriculturists (the Nasioi, on Bougainville, and the Kwaio and Baegu, on Malaita). The Nasioi were darker than the Malaitans and spoke a non-Austronesian rather than a Melanesian language; they were also more Westernized. Coverage of residents in designated hamlets ranged from 78% to over 95%. In all, 1,626 persons were studied: 256 Nasioi, 443 Kwaio, 442 Lau, and 485 Baegu. Genetic differences have been found between the Nasioi and the Malaitans, and between the Lau and the other Malaitans.     

Characterization of a Strain of Fukuyoa paulensis (Dinophyceae) from the Western Mediterranean Sea

A single cell of the dinoflagellate genus Fukuyoa was isolated from the island of Formentera (Balearic Islands, west Mediterranean Sea), cultured, and characterized by morphological and molecular methods and toxin analyses. This is the first report of the Gambierdiscus lineage (genera Fukuyoa and Gambierdiscus) from the western Mediterranean Sea, which is cooler than its eastern basin. Molecular analyses revealed that the Mediterranean strain belongs to F. paulensis and that it bears LSU rDNA sequences identical to New Zealand, Australian, and Brazilian strains. It also shared an identical sequence of the more variable ITS‐rDNA with the Brazilian strain. Toxin analyses showed the presence of maitotoxin, 54‐deoxyCTX1B, and gambieric acid A. This is the first observation of the two latter compounds in a Fukuyoa strain. Therefore, both Gambierdiscus and Fukuyoa should be considered when as contributing to ciguatera fish poisoning. Different strains of Fukuyoa form a complex of morphologically cryptic lineages where F. paulensis stands as the most distantly related nominal species. The comparison of the ITS2 secondary structures revealed the absence of CBCs among strains. The study of the morphological and molecular traits depicted an unresolved taxonomic scenario impacted by the low strains sampling.     

Raptors as legitimate secondary dispersers of weed seeds

Although raptors are not usually seen as seed dispersers, we demonstrate their important ecological role as legitimate seed dispersers of weeds. On the oceanic island of Fuerteventura in the Canary Islands, up to 11 000 weed seeds from a total of 39 and 62 different plant species, respectively, were found in 300 and 319 pellets, respectively, of two native predatory birds, the Common Buzzard Buteo buteo and the Eurasian Kestrel Falco tinnunculus, which consumed European Rabbits Oryctolagus cuniculus and Barbary Ground Squirrels Atlantoxerus getulus, both invasive mammals that carried these seeds in their guts. Four and seven weed species appeared with a frequency of occurrence greater than 10% in the pellets of Kestrels and Buzzards, respectively. Despite the time interval between pellet collection and germination experiments, almost 10% of planted seeds germinated, even after passing through two digestive processes, one inside the mammal and another inside the raptor. Our study encourages a change of perspective in this regard, as raptors may be involved in complex interactive dispersal processes on a wider geographical scale.     

Wing morphology of the active flyer Calliphora vicina (Diptera: Calliphoridae) during its invasion of a sub‐Antarctic archipelago where insect flightlessness is the rule

The cosmopolitan blowfly Calliphora vicina became established in the sub‐Antarctic Kerguelen Islands in the late 1970s, following a warming period that allowed its full development. Although temperature and wind may limit flight activity, the fly invaded the archipelago, reaching sites remote from the introduction point. Most native competitors have converged to flightlessness as a response to stringent environmental conditions and therefore the flight strategy of C. vicina might be either a handicap or a competitive advantage under ongoing climate change. Using geometric morphometrics, we investigated whether the wing had changed over time in C. vicina within the archipelago (1998 vs. 2009) and compared its morphology with that of a continental population from a temperate area (1983 vs. 2009). Wing shape plasticity to temperature was also experimentally investigated. We found no clues of relaxed selection on flight morphology in the range invaded. However, rapid changes of wing shape occurred over time in females from the Kerguelen Islands compared with both males and females of the continental population, despite a shorter time‐lag between samples in the former. The thermal reaction norms for wing shape found for C. vicina from Kerguelen were also different from those of the continental population, but it remains unknown whether this resulted from or preceded the introduction. These combined findings are consistent with a fingerprint of local adaptation in the invasive population. However, the adaptive significance of the changes, in terms of their aerodynamic consequences and the future evolution of C. vicina in the Kerguelen Islands, requires further investigation. From an evolutionary standpoint, sustaining flight capability under the novel sub‐Antarctic conditions might be critical to the invasive success of C. vicina as most competitors are flightless.     

Habitat relationships of forest birds on Tutuila Island, American Samoa

Aim Our knowledge of landbirds on tropical Pacific islands is often comprised of brief, one-time surveys. We know little of species’ habitat preferences, and this information is critical for understanding the resource requirements or population status of native species and the impacts of human activity on island birds. Location Tutuila Island, American Samoa. Methods The spatial patterns in forest birds were investigated. This island harbours large tracts of native forest, a variety of disturbed and non-native forests, and some relatively healthy bird populations. The distribution of birds was correlated with forest types using habitat data collected at fifty-seven sites and avian census data collected monthly for 1–4 years at these sites. Results Differences in location and in vegetation structure and composition between native and non-native habitats are important influences on the distribution of birds on Tutuila. Among native species, for example, the purple-capped fruit-dove (Ptilinopus porphyraceus Temminck) is dependent upon native habitat, the Samoan starling (Aplonis atrifusca Peale) occurs in all habitats, and the cardinal honeyeater (Myzomela cardinalis Gmelin) is more abundant in low elevation, non-native habitat. Conclusions This research reinforces the importance of quantitative assessment of habitat relationships in the study and conservation of Pacific birds.     

Adaptive radiation and genetic differentiation in the woodySonchus alliance (Asteraceae:Sonchinae) in the Canary Islands

The woodySonchus alliance consists of 19 species ofSonchus subg.Dendrosonchus, one species ofSonchus subg.Sonchus and species of five genera (i.e.Babcockia, Sventenia, Taeckholmia, Lactucosonchus, Prenanthes), and is restricted primarily to the archipelago of the Canaries in the Macaronesian phytogeographical region. An enzyme electrophoretic study, including 13 loci, was conducted to assess genetic diversity within and divergence among species of the alliance. Nei's genetic identities (distances) between genera and/or subgenera range from 0.490 (0.714) to 0.980 (0.013), and pairwise comparisons of all populations show relatively high genetic identities, with a mean of 0.804. The high identities further support the genetic cohesiveness of the alliance and its single origin on the Macaronesian islands. Species in the alliance also show about 50%; higher total genetic diversity (H_T) than the mean for other oceanic endemics. There is greater divergence between endemics or species on older islands compared to those on younger islands, which suggests that time is a factor for divergence at allozyme loci. Furthermore, populations on older islands have higher total genetic diversities and lower identities than conspecific populations on younger islands. These results imply early colonization, radiation, and divergence of the woodySonchus alliance on older islands followed by subsequent colonization to younger islands. The taxonomic distribution of alleles in the alliance indicates lineage sorting also played a role in divergence among species. Lineage sorting may also produce nonconcordance with either taxonomic designation or the pattern of variation obtained from other molecular markers such as ITS sequences of nrDNA. Timing for the origin and radiation of the alliance agrees with the estimate based on ITS sequences, and suggests that the early divergence and rapid radiation took place during the Late Tertiary on either Gran Canaria or Tenerife.     

Origin and dispersion pathways of guava in the Galapagos Islands inferred through genetics and historical records

Guava (Psidium guajava) is an aggressive invasive plant in the Galapagos Islands. Determining its provenance and genetic diversity could explain its adaptability and spread, and how this relates to past human activities. With this purpose, we analyzed 11 SSR markers in guava individuals from Isabela, Santa Cruz, San Cristobal, and Floreana islands in the Galapagos, as well as from mainland Ecuador. The mainland guava population appeared genetically differentiated from the Galapagos populations, with higher genetic diversity levels found in the former. We consistently found that the Central Highlands region of mainland Ecuador is one of the most likely origins of the Galapagos populations. Moreover, the guavas from Isabela and Floreana show a potential genetic input from southern mainland Ecuador, while the population from San Cristobal would be linked to the coastal mainland regions. Interestingly, the proposed origins for the Galapagos guava coincide with the first human settlings of the archipelago. Through approximate Bayesian computation, we propose a model where San Cristobal was the first island to be colonized by guava from the mainland, and then, it would have spread to Floreana and finally to Santa Cruz; Isabela would have been seeded from Floreana. An independent trajectory could also have contributed to the invasion of Floreana and Isabela. The pathway shown in our model agrees with the human colonization history of the different islands in the Galapagos. Our model, in conjunction with the clustering patterns of the individuals (based on genetic distances), suggests that guava introduction history in the Galapagos archipelago was driven by either a single event or a series of introduction events in rapid succession. We thus show that genetic analyses supported by historical sources can be used to track the arrival and spread of invasive species in novel habitats and the potential role of human activities in such processes.