Sandra Reis

First record of Aedes albopictus (Skuse 1894) on São tomé island

Biological invasions have critical impacts on native biodiversity and human societies and especially on oceanic islands that are fragile and threatened ecosystems. The invasive tiger mosquito Aedes (Stegomyia) albopictus (Skuse, 1894) native to Southeast Asia has been introduced during the past 30 years almost everywhere in the world, including the Americas, the Pacific, Europe and Africa. It has been reported for the first time in the Gulf of Guinea in 2000, first in Cameroon, then in Bioko Island in 2003 and more recently in Gabon in 2007. Here we report the first record of Ae. albopictus on São Tomé Island. Although we cannot estimate precisely the year of introduction on São Tomé Island, it most likely arrived within the last 10 years. By sequencing the mitochondrial cytochrome c oxidase gene from individual adults, we detected three haplotypes already present in mainland Africa. More studies are needed to explore the dynamics of its expansion and competition with insular native mosquitoes.

Insularity effects on bird immune parameters: A comparison between island and mainland populations in West Africa

Abstract Oceanic islands share several environmental characteristics that have been shown to drive convergent evolutionary changes in island organisms. One change that is often assumed but has seldom been examined is the evolution of weaker immune systems in island species. The reduction in species richness on islands is expected to lead to a reduced parasite pressure and, given that immune function is costly, island animals should show a reduced immune response. However, alternative hypotheses exist; for example, the slower pace of life on islands could favor the reorganization of the immune system components (innate vs. acquired immunity) on islands. Thus far, few island species have been studied and no general patterns have emerged. Here, we compared two immune parameters of birds from São Tomé and Príncipe islands to those of their close relatives at similar latitudes on the mainland (Gabon, West Africa). On islands, the acquired humoral component (total immunoglobulins) was lower for most species, whereas no clear pattern was detected for the innate component (haptoglobin levels). These different responses did not seem to arise from a reorganization of the two immune components, as both total immunoglobulins and haptoglobin levels were positively associated. This work adds to the few empirical studies conducted so far which suggest that changes in immune parameters in response to insularity are not as straightforward as initially thought.

A test of the European Pleistocene refugial paradigm, using a Western Palaearctic endemic bird species

Hewitts paradigm for effects of Pleistocene glaciations on European populations assumes their isolation in peninsular refugia during glacial maxima, followed by re-colonization of broader Europe during interstadials. This paradigm is well supported by studies of poorly dispersing taxa, but highly dispersive birds have not been included. To test this paradigm, we use the dunnock (Prunella modularis), a Western Palaearctic endemic whose range includes all major European refugia. MtDNA gene tree, multilocus species tree and species delimitation analyses indicate the presence of three distinct lineages: one in the Iberian refugium, one in the Caucasus refugium, and one comprising the Italian and Balkan refugia and broader Europe. Our gene flow analysis suggests isolation of both the Iberian and Caucasus lineages but extensive exchange between Italy, the Balkans and broader Europe. Demographic stability could not be rejected for any refugial population, except the very recent expansion in the Caucasus. By contrast, northern European populations may have experienced two expansion periods. Iberia and Caucasus had much smaller historical populations than other populations. Although our results support the paradigm, in general, they also suggest that in highly dispersive taxa, isolation of neighbouring refugia was incomplete, resulting in large super-refugial populations.