Philaenus spumarius is a widespread insect species in the Holarctic region. Here, by focusing on the mtDNA gene COI but also using the COII and Cyt b genes and the nuclear gene EF-1α, we tried to explain how and when its current biogeographic pattern evolved by providing time estimates of the main demographic and evolutionary events and investigating its colonization patterns in and out of Eurasia. Evidence of recent divergence and expansion events at less than 0.5 Ma ago indicate that climate fluctuations in the Mid-Late Pleistocene were important in shaping the current phylogeographic pattern of the species. Data support a first split and differentiation of P. spumarius into two main mitochondrial lineages: the “western”, in the Mediterranean region and the “eastern”, in Anatolia/Caucasus. It also supports a following differentiation of the “western” lineage into two sub-lineages: the “western-Mediterranean”, in Iberia and the “eastern-Mediterranean” in the Balkans. The recent pattern seems to result from postglacial range expansion from Iberia and Caucasus/Anatolia, thus not following one of the four common paradigms. Unexpected patterns of recent gene-flow events between Mediterranean peninsulas, a close relationship between Iberia and North Africa, as well as high levels of genetic diversity being maintained in northern Europe were found. The mitochondrial pattern does not exactly match to the nuclear pattern suggesting that the current biogeographic pattern of P. spumarius may be the result of both secondary admixture and incomplete lineage sorting. The hypothesis of recent colonization of North America from both western and northern Europe is corroborated by our data and probably resulted from accidental human translocations. A probable British origin for the populations of the Azores and New Zealand was revealed, however, for the Azores the distribution of populations in high altitude native forests is somewhat puzzling and may imply a natural colonization of the archipelago.
Human‐mediated introductions of species may have profound impacts on native ecosystems. One potential impact with largely unforeseen consequences is the potential admixture of introduced with autochthonous species through hybridization. Throughout the world, bumblebees have been deliberately introduced for crop pollination with known negative impacts on native pollinators. Given the likely allochthonous origin of commercial bumblebees used in Portugal (subspecies Bombus terrestris terrestris and B. t. dalmatinus ), our aim was to assess their putative introgression with the native Iberian subspecies B. terrestris lusitanicus. We analysed one mitochondrial gene, cytochrome c oxidase subunit I (COX1) and genomic data involving thousands of genome‐wide restriction‐site‐associated DNA markers (RAD‐seq). In the mitochondrial COX1 analyses, we detected one relatively common haplotype in commercial bumblebees, also present in wild samples collected nearby the greenhouses where the commercial hives are used. In the RAD‐seq analysis, we found a clear genetic differentiation between native and commercial lineages. Furthermore, we detected candidate hybrids in the wild, as well as putatively escaped commercial bumblebees, some of which being potentially fertile males. Although we cannot assess directly the fitness effects of introgressed alleles, there is a risk of maladaptive allele introgression to the local bumblebee subspecies, which can negatively impact autochthon populations. One immediate recommendation to farmers is for the proper disposal of hive boxes, after their use in greenhouses, so as to minimize the risk of escapees contaminating native populations. On the other hand, the feasibility of using local subspecies B. t. lusitanicus , preferably with local production, should be evaluated.
We provide a comprehensive overview of those Lepidopteran invasions to Europe that result from increasing globalisation and also review expansion of species within Europe. A total of 97 non-native Lepidoptera species (about 1% of the known fauna), in 20 families and 11 superfamilies have established so far in
DNA barcodes have great potential to assist in species identification, especially when high taxonomical expertise is required. We investigated the utility of the 5' mitochondrial cytochrome c oxidase I (COI) region to discriminate between 13 European cicada species. These included all nine species currently recognized under the genus Tettigettalna, from which seven are endemic to the southern Iberian Peninsula. These cicadas have species-specific male calling songs but are morphologically very similar. Mean COI divergence between congeners ranged from 0.4% to 10.6%, but this gene was proven insufficient to determine species limits within genus Tettigettalna because a barcoding gap was absent for several of its species, that is, the highest intraspecific distance exceeded the lowest interspecific distance. The genetic data conflicted with current taxonomic classification for T. argentata and T. mariae. Neighbour-joining and Bayesian analyses revealed that T. argentata is geographically structured (clades North and South) and might constitute a species complex together with T. aneabi and T. mariae. The latter diverges very little from the southern clade of T. argentata and shares with it its most common haplotype. T. mariae is often in sympatry with T. argentata but it remains unclear whether introgression or incomplete lineage sorting may be responsible for the sharing of haplotypes. T. helianthemi and T. defauti also show high intraspecific variation that might signal hidden cryptic diversity. These taxonomic conflicts must be re-evaluated with further studies using additional genes and extensive morphological and acoustic analyses.
Ongoing climate change is expected to cause an increase in temperature and a reduction of precipitation levels in the Mediterranean region, which might cause changes in many species distributions. These effects negatively influence species gene pools, decreasing genetic variability and adaptive potential. Here, we use mitochondrial DNA and RADseq to analyse population genetic structure and genetic diversity of the bumblebee species Bombus terrestris (subspecies Bombus terrestris lusitanicus), in the Iberian Peninsula. Although this subspecies shows a panmictic pattern of population structure across Iberia and beyond, we found differentiation between subspecies B. t. lusitanicus and B. t. africanus, probably caused by the existence of barriers to gene flow between Iberia and North Africa. Furthermore, the results revealed that the Iberian Peninsula harbours a large fraction of B. terrestris intraspecific genetic variation, with the highest number of mitochondrial haplotypes found when compared with any other region in Europe studied so far, suggesting a potential role for the Iberian Peninsula as a glacial refugium. Our findings strengthen the idea that Iberia is a very important source of diversity for the global genetic pool of this species, because rare alleles might play a role in population resilience against human- or climate-mediated changes.
Understanding patterns of population differentiation and gene flow in insect vectors of plant diseases is crucial for the implementation of management programs of disease. We investigated morphological and genome-wide variation across the distribution range of the spittlebug Philaenus spumarius (Linnaeus, 1758) (Hemiptera, Auchenorrhyncha, Aphrophoridae), presently the most important vector of the plant pathogenic bacterium Xylella fastidiosa Wells et al., 1987 in Europe. We found genome-wide divergence between P. spumarius and a very closely related species, P. tesselatus Melichar, 1899, at RAD sequencing markers. The two species may be identified by the morphology of male genitalia but are not differentiated at mitochondrial COI, making DNA barcoding with this gene ineffective. This highlights the importance of using integrative approaches in taxonomy. We detected admixture between P. tesselatus from Morocco and P. spumarius from the Iberian Peninsula, suggesting gene-flow between them. Within P. spumarius, we found a pattern of isolation-by-distance in European populations, likely acting alongside other factors restricting gene flow. Varying levels of co-occurrence of different lineages, showing heterogeneous levels of admixture, suggest other isolation mechanisms. The transatlantic populations of North America and Azores were genetically closer to the British population analyzed here, suggesting an origin from North-Western Europe, as already detected with mitochondrial DNA. Nevertheless, these may have been produced through different colonization events. We detected SNPs with signatures of positive selection associated with environmental variables, especially related to extremes and range variation in temperature and precipitation. The population genomics approach provided new insights into the patterns of divergence, gene flow and adaptation in these spittlebugs and led to several hypotheses that require further local investigation.
Morocco has been the subject of very few expeditions on the last century with the objective of studying small cicadas. In the summer of 2014 an expedition was carried out to Morocco to update our knowledge with acoustic recordings and genetic data of these poorly known species. We describe here two new small-sized cicadas that could not be directly assigned to any species of North African cicadas: Tettigettalna afroamissa sp. nov. and Berberigetta dimelodica gen. nov. & sp. nov. In respect to T. afroamissa it is the first species of the genus to be found outside Europe and we frame this taxon within the evolutionary history of the genus. Acoustic analysis of this species allows us to confidently separate T. afroamissa from its congeners. With B. dimelodica, a small species showing a remarkable calling song characterized by an abrupt frequency modulation, a new genus had to be erected. Bayesian inference and maximum likelihood phylogenetic analyses with DNA-barcode sequences of Cytochrome C Oxidase 1 support the monophyly of both species, their distinctness and revealed genetic structure within B. dimelodica. Alongside the descriptions we also provide GPS coordinates of collection points, distributions and habitat preferences.
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