Browsing by Author "Silva, Sara E."
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- Assessing genotype-phenotype associations in three dorsal colour morphs in the meadow spittlebug Philaenus spumarius (L.) (Hemiptera: Aphrophoridae) using genomic and transcriptomic resourcesPublication . Rodrigues, Ana S. B.; Silva, Sara E.; Pina-Martins, Francisco; Loureiro, João; Castro, Mariana; Gharbi, Karim; Johnson, Kevin P.; Dietrich, Christopher H.; Borges, P.A.V.; Quartau, J. A.; Jiggins, Chris D.; Paulo, Octávio S.; Seabra, Sofia G.Colour polymorphisms are common among animal species. When combined with genetic and ecological data, these polymorphisms can be excellent systems in which to understand adaptation and the molecular changes underlying phenotypic evolution. The meadow spittlebug, Philaenus spumarius (L.) (Hemiptera, Aphrophoridae), a widespread insect species in the Holarctic region, exhibits a striking dorsal colour/pattern balanced polymorphism. Although experimental crosses have revealed the Mendelian inheritance of this trait, its genetic basis remains unknown. In this study we aimed to identify candidate genomic regions associated with the colour balanced polymorphism in this species.
- Genomic Patterns of Iberian Wild Bees Reveal Levels of Diversity, Differentiation and Population Structure, Supporting the “Refugia within Refugia” HypothesisPublication . Sousa, Paulo de; Henriques, André; Silva, Sara E.; Carvalheiro, Luísa G.; Smagghe, Guy; Michez, Denis; Wood, Thomas J.; Paulo, Octávio S.We used a population genomic approach to unravel the population structure, genetic differentiation, and genetic diversity of three widespread wild bee species across the Iberian Peninsula, Andrena agilissima, Andrena flavipes and Lasioglossum malachurum. Our results demonstrated that genetic lineages in the Ebro River valley or near the Pyrenees mountains are different from the rest of Iberia. This relatively congruent pattern across species once more supports the hypothesis of “refugia within refugia” in the Iberian Peninsula. The results for A. flavipes and A. agilissima showed an unexpected pattern of genetic differentiation, with the generalist polylectic A. flavipes having lower levels of genetic diversity (Ho = 0.0807, He = 0.2883) and higher differentiation (FST = 0.5611), while the specialist oligolectic A. agilissima had higher genetic diversity (Ho = 0.2104, He = 0.3282) and lower differentiation values (FST = 0.0957). For L. malachurum, the smallest and the only social species showed the lowest inbreeding coefficient (FIS = 0.1009) and the lowest differentiation level (FST = 0.0663). Overall, our results, suggest that this pattern of population structure and genetic diversity could be explained by the combined role of past climate changes and the life-history traits of the species (i.e., size, sociality and host-plant specialization), supporting the role of the Iberian refugia as a biodiversity hotspot.
- Genomic signatures of introgression between commercial and native bumblebees, Bombus terrestris, in Western Iberian Peninsula - implications for conservation and trade regulationPublication . Seabra, Sofia G.; Silva, Sara E.; Nunes, Vera L.; Sousa, Vitor C.; Martins, Joana; Marabuto, Eduardo; Rodrigues, Ana S.B.; Pina-Martins, Francisco; Laurentino, Telma G.; Rebelo, Maria Teresa; Figueiredo, Elisabete; Paulo, Octávio S.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
- Genomic signatures of introgression between commercial and native bumblebees, Bombus terrestris, in western Iberian Peninsula—Implications for conservation and trade regulationPublication . Seabra, Sofia G.; Silva, Sara E.; Nunes, Vera L.; Sousa, Vitor C; Martins, Joana; Marabuto, Eduardo; Rodrigues, Ana S. B.; Pina Martins, Francisco; Laurentino, Telma G.; Rebelo, Maria Teresa; Figueiredo, Elisabete; Paulo, Octávio S.Human‐mediated introductions of species may have profound impacts on native eco ‐systems. 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 pol ‐lination with known negative impacts on native pollinators. Given the likely alloch ‐thonous origin of commercial bumblebees used in Portugal (subspecies Bombus terrestris terrestris and B. t. dalmatinus), our aim was to assess their putative introgres‐sion with the native Iberian subspecies B. terrestris lusitanicus. We analysed one mito ‐chondrial 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 green ‐houses 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 commercialbumblebees, some of which being potentially fertile males. Although we cannot as ‐sess 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 feasibilityof using local subspecies B. t. lusitanicus, preferably with local production, should be evaluated.
- New Mitochondrial and Nuclear Evidences Support Recent Demographic Expansion and an Atypical Phylogeographic Pattern in the Spittlebug Philaenus spumarius (Hemiptera, Aphrophoridae)Publication . Rodrigues, Ana S. B.; Silva, Sara E.; Marabuto, Eduardo; Silva, Diogo N.; Wilson, Mike R.; Thompson, Vinton; Yurtsever, Selçuk; Halkka, Antti; Borges, P.A.V.; Quartau, J. A.; Paulo, Octávio S.; Seabra, Sofia G.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.
- Population genomics of Bombus terrestris reveals high but unstructured genetic diversity in a potential glacial refugiumPublication . Silva, Sara E.; Seabra, Sofia G.; Carvalheiro, Luísa G.; Nunes, Vera L.; Marabuto, Eduardo; Mendes, Raquel; Rodrigues, Ana S.B.; Pina-Martins, Francisco; Yurtsever, Selçuc; Laurentino, Telma G.; Figueiredo, Elisabete; Rebelo, Maria T.; Paulo, Octávio S.Ongoing climate change is expected to cause temperature rise and reduction of precipitation levels in the Mediterranean region, which might cause changes in many species’ distribution. These effects negatively impact 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 B. terrestris lusitanicus), in the Iberian Peninsula. While this subspecies shows a panmictic pattern of population structure across Iberia and beyond, we found differentiation between subspecies lusitanicus and subspecies africanus, likely caused by the existence of barriers to gene flow between Iberia and North Africa. Furthermore, 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 to any other region in Europe studied so far, suggesting a potential glacial refugium role for the Iberian Peninsula. Our findings strengthen the idea that Iberia is a very important source of diversity for the global genetic pool of this species, as rare alleles may play a role in population resilience against human or climate-mediated changes
- Testing drivers of acoustic divergence in cicadas (Cicadidae: Tettigettalna )Publication . Gonçalves Mendes, Raquel; Nunes, Vera L.; Marabuto, Eduardo; Costa, Gonçalo J.; Silva, Sara E.; Paulo, Octávio S.; Simões, Paula C.Divergence in acoustic signals may have a crucial role in the speciation process of ani-mals that rely on sound for intra-specific recognition and mate attraction. The acous-tic adaptation hypothesis (AAH) postulates that signals should diverge according to the physical properties of the signalling environment. To be efficient, signals should maximize transmission and decrease degradation. To test which drivers of divergence exert the most influence in a speciose group of insects, we used a phylogenetic ap-proach to the evolution of acoustic signals in the cicada genus Tettigettalna, inves-tigating the relationship between acoustic traits (and their mode of evolution) and body size, climate and micro-/macro- habitat usage. Different traits showed different evolutionary paths. While acoustic divergence was generally independent of phyloge-netic history, some temporal variables’ divergence was associated with genetic drift. We found support for ecological adaptation at the temporal but not the spectral level. Temporal patterns are correlated with micro- and macro- habitat usage and tempera-ture stochasticity in ways that run against the AAH predictions, degrading signals more easily. These traits are likely to have evolved as an anti- predator strategy in conspicuous environments and low-density populations. Our results support a role of ecological selection, not excluding a likely role of sexual selection in the evolution of Tettigettalna calling songs, which should be further investigated in an integrative approach.