Background: SINEs (Short INterspersed Elements) are homoplasy-free and co-dominant genetic markers which are considered to represent useful tools for population genetic studies, and could help clarifying the speciation processes ongoing within the major malaria vector in Africa, Anopheles gambiae s.s. Here, we report the results of the analysis of the insertion polymorphism of a nearly 200 bp-long SINE (SINE200) within genome areas of high differentiation (i.e. "speciation islands") of M and S A. gambiae molecular forms.

The main Afrotropical malaria vector, Anopheles gambiae sensu stricto, is undergoing a process of sympatric ecological diversification leading to at least two incipient species (the M and S molecular forms) showing heterogeneous levels of divergence across the genome. The physically unlinked centromeric regions on all three chromosomes of these closely related taxa contain fixed nucleotide differences which have been found in nearly complete linkage disequilibrium in geographic areas of no or low M-S hybridization. Assays diagnostic for SNP and structural differences between M and S forms in the three centromeric regions were applied in samples from the western extreme of their range of sympatry, the only area where high frequencies of putative M/S hybrids have been reported. The results reveal a level of admixture not observed in the rest of the range. In particular, we found: i) heterozygous genotypes at each marker, although at frequencies lower than expected under panmixia; ii) virtually all possible genotypic combinations between markers on different chromosomes, although genetic association was nevertheless detected; iii) discordant M and S genotypes at two X-linked markers near the centromere, suggestive of introgression and inter-locus recombination. These results could be indicative either of a secondary contact zone between M and S, or of the maintenance of ancestral polymorphisms. This issue and the perspectives opened by these results in the study of the M and S incipient speciation process are discussed.

A molecular analysis was carried out on the European hermit beetles (the Osmoderma eremita species complex) to explore their genetic diversification and the robustness of previous morphologically based taxonomic arrangements. Complete sequences of mtDNA cytochrome C oxidase I gene were obtained from 26 individuals. Mean levels of interspecific sequence divergence ranged from 0.044 to 0.186. The results indicate a clear-cut distinction between two clades. The first one includes the W-European O. eremita Scopoli 1763; and the two Italian endemic taxa Osmoderma italicum Sparacio, 2000 and Osmoderma cristinae Sparacio, 1994; from southern peninsular Italy and Sicily, respectively. The second one includes the widespread E-European Osmoderma barnabita; and the southern Balcanic Osmoderma lassallei Baraud and Tauzin, 1991 from Greece and European Turkey. Within the two clades, molecular and morphological data well support a specific rank for O. lassallei and O. barnabita on one side, and for O. eremita and O. cristinae on the other side, while the taxonomic position of O. italicum, more closely related to O. eremita, is still uncertain. Current geographical distribution, interspecific genetic diversification, and very low levels of intraspecific genetic divergence in western European populations of O. eremita sensu stricto are hypothesized to be the result of multiple speciation events (mainly occurred in refugial forest areas of the Italian and Balkan peninsulas and Sicily before and during the Pleistocene glacial peaks), followed by fast post-glacial northward and westward expansion of some species.

Results of a molecular analysis on the European hermit beetles (the <em>Osmoderma</em> <em>eremita</em> species-complex), recently published in a companion paper, are shortly dis- cussed and commented. These results indicate a clear-cut distinction between two clades. The first one includes the W-European <em>O. eremita</em> Scopoli, 1763, and the two Italian endemic taxa <em>O. italicum</em> Sparacio, 2000 and <em>O. cristinae</em> Sparacio, 1994, from southern peninsular Italy and Sicily, respectively. The second one includes the widespread E-European<em> O. barnabita</em> Motschulsky, 1845 (<strong>nom. resurr</strong>.), and the southern Balcanic <em>O. lassallei</em> Baraud &amp; Tauzin, 1991 from Greece and European Turkey. Within the two clades, molecular data well support a specific rank for <em>O. lassallei</em> and <em>O. barn­abita</em> on one side, and of <em>O.</em> <em>eremita</em> and <em>O. cristinae</em> on the other side, while the taxonomic position of <em>O. italicum</em>, more closely related with <em>O. eremita</em>, is still uncertain, waiting for analysis of additional specimens of this very rare taxon. Current geographical distribution, interspecific genetic diversification, and relatively low levels of intraspecific genetic divergence in <em>O. eremita</em> sensu stricto, are hypothesized to be the result of multiple speciation events (mainly occurred in refugial forest areas of the Italian and Balkan peninsulas and Sicily before and during the Pleistocene glacial peaks), followed by fast post-glacial northward and westward expansion of some species. The need of further genetic data on the rare and threatened hermit beetle species and the importance of more detailed information on their distribution ranges are emphasized and discussed, in order to plan conservation strategies in the near future. An updated worldwide checklist of the species of the genus <em>Osmoderma</em> is finally presented.

Molecular analyses on the Brassicogethes coracinus species complex (pollen beetles associated with Brassicaceae) were performed to explore genetic and ecological diversification, and robustness of the current morphologically based classification. Complete COI sequences (1,542 bp) were obtained from 69 individuals assigned to 10 recognized species and from 5 individuals of the designated outgroup (B. aeneus). Mean interspecific divergence within the clade varied from 0.005 to 0.283. The species B. epeirosi, B. subaeneus and B. cantabricus were associated with the tribe Arabideae and found to occupy basal most positions in the phylogeny, whereas all other species, mostly associated with the tribe Hesperideae, grouped together. In the latter group, B. erysimicola and B. coracinus occupied a basal position adjacent to a wider cluster of mixed haplotypes, likely, due to incomplete lineage sorting or past hybridization events. New data based on nuclear genetic markers are currently being collected to pursue a multilocus analysis. © Springer-Verlag 2012

Despite the effectiveness of mass distribution of long-lasting insecticidal nets (LLINs) in reducing malaria transmission in Africa, in hyperendemic areas such as Burkina Faso the burden of malaria remains high. We here report the results of a 4-month survey on the feeding habits and Plasmodium infection in malaria vectors from a village in Burkina Faso one year following a national LLIN distribution programme. Low values of human blood index (HBI) observed in the major malaria vectors in the area (Anopheles coluzzii: N = 263, 20.1%; An. arabiensis: 5.8%, N = 103) are consistent with the hypothesis that LLINs reduced the availability of human hosts to mosquitoes. A regression meta-analysis of data from a systematic review of published studies reporting HBI and sporozoite rates (SR) for An. gambiae complex revealed that the observed SR values (An. coluzzii: 7.6%, N = 503; An. arabiensis: 5.3%, N = 225) are out of the ranges expected based on the low HBI observed. We hypothesize that a small fraction of inhabitants unprotected by bednets acts as a “core group” repeatedly exposed to mosquito bites, representing the major Plasmodium reservoir for the vectors, able to maintain a high risk of transmission even in a village protected by LLINs.

Impacts of introgressive hybridisation may range from genomic erosion and species collapse to rapid adaptation and speciation but opportunities to study these dynamics are rare. We investigated the extent, causes and consequences of a hybrid zone between Anopheles coluzzii and Anopheles gambiae in Guinea-Bissau, where high hybridisation rates appear to be stable at least since the 1990s. Anopheles gambiae was genetically partitioned into inland and coastal subpopulations, separated by a central region dominated by A. coluzzii. Surprisingly, whole genome sequencing revealed that the coastal region harbours a hybrid form characterised by an A. gambiae-like sex chromosome and massive introgression of A. coluzzii autosomal alleles. Local selection on chromosomal inversions may play a role in this process, suggesting potential for spatiotemporal stability of the coastal hybrid form and providing resilience against introgression of medically-important loci and traits, found to be more prevalent in inland A. gambiae.

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