Evidence for divergent selection between the molecular forms of Anopheles gambiae: role of predation

The molecular forms of Anopheles gambiae are undergoing speciation. They are characterized by a strong assortative mating and they display partial habitat segregation. The M form is mostly found in flooded/irrigated areas whereas the S form dominates in the surrounding areas, but the ecological factors that shape this habitat segregation are not known. Resource competition has been demonstrated between species undergoing divergent selection, but resource competition is not the only factor that can lead to divergence. In a field experiment using transplantation of first instar larvae, we evaluated the role of larval predators in mediating habitat segregation between the forms. We found a significant difference in the ability of the molecular forms to exploit the different larval sites conditioned on the presence of predators. In absence of predation, the molecular forms outcompeted each other in their respective natural habitats however, the developmental success of the M form was significantly higher than that of the S form in both habitats under predator pressure. Our results provide the first empirical evidence for specific adaptive differences between the molecular forms and stress the role of larval predation as one of the mechanisms contributing to their divergence.https://doi.org/10.1186/1471-2148-8-

Data from: Rates and processes of aeolian soil erosion in West Greenland

In arid landscapes across the globe, aeolian processes are key drivers of landscape change, but arid Arctic regions are often overlooked. In the Kangerlussuaq region of West Greenland, strong katabatic winds have removed discrete patches of soil and vegetation, exposing unproductive glacial till and bedrock. Although lake-sediment records suggest that landscape destabilization began approximately 1000 years ago, the upland soil erosion has never been directly dated. We use a novel application of lichenometry to estimate the rates and timing of soil erosion. We show that the formation of deflation patches occurred approximately 800–230 years ago, in general agreement with lake-sediment records. In West Greenland, the ‘Little Ice Age’ (AD 1350–1880) was characterized by a cold and arid climate, conditions that increased susceptibility to erosion. On average, deflation patches are expanding at a rate of 2.5 cm yr−1, and variation in the rate of patch expansion cannot be explained by proximity to the Greenland Ice Sheet (GrIS), slope, aspect, elevation, or patch size. An erosional threshold exists in this aeolian system, with climate conditions necessary for patch formation likely harsher than those necessary for continued patch expansion, a result that has implications for land management in arid regions. Currently, deflation patches are expanding throughout the study region and are forming in areas close to the GrIS, but future deflation rates are dependent on projected climate and potential land-use changes. Our results stress the importance of aeolian processes in arid polar landscapes such as Kangerlussuaq, and demonstrate the use of aeolian landforms in paleoclimate reconstructions and predicting future landscape change

Larval developmental success (measured as the number of adults per cage) of the molecular forms in presence and absence of predators in puddles and rice fields

<p><b>Copyright information:</b></p><p>Taken from "Evidence for divergent selection between the molecular forms of : role of predation"</p><p>http://www.biomedcentral.com/1471-2148/8/5</p><p>BMC Evolutionary Biology 2008;8():5-5.</p><p>Published online 11 Jan 2008</p><p>PMCID:PMC2217532.</p><p></p> The box extends between the 25and the 75percentile (across the inter quartile range – IQR) and the median is denoted by a thick line. The whiskers extend up to the most extreme value, up to 1.5 times the IQR and values located over 2 IQR from the median are shown. The triangles extend from the mean (base) to 1 SD (tip)

Predator composition in rice fields (empty squares) and puddles (filled squares)

<p><b>Copyright information:</b></p><p>Taken from "Evidence for divergent selection between the molecular forms of : role of predation"</p><p>http://www.biomedcentral.com/1471-2148/8/5</p><p>BMC Evolutionary Biology 2008;8():5-5.</p><p>Published online 11 Jan 2008</p><p>PMCID:PMC2217532.</p><p></p> Bars denote mean density in 10 samples of rice fields and 9 samples of puddles of each predator. Stars above bars denote significant difference in a single test. Inset shows clustering of samples based on their predator composition using Principal Component (PC) analysis. Coordinates are the first (horizontal) and second principal components. The first PC represented overall predator abundance because its eigenvector's loadings were positive and similar in magnitude (except for the negative loading of the dragonfly; not shown). It alone accounted for 38% of the total variation and together with the second PC, 64% of the total variation was captured

Status and trends of terrestrial arthropod abundance and diversity in the North Atlantic region of the Arctic

The Circumpolar Biodiversity Monitoring Programme (CBMP) provides an opportunity to improve our knowledge of Arctic arthropod diversity, but initial baseline studies are required to summarise the status and trends of planned target groups of species known as Focal Ecosystem Components (FECs). We begin this process by collating available data for a relatively well-studied region in the Arctic, the North Atlantic region, summarising the diversity of key terrestrial arthropod FECs, and compiling trends for some representative species. We found the FEC classification system to be challenging to implement, but identified some key groups to target in the initial phases of the programme. Long-term data are scarce and exhibit high levels of spatial and temporal variability. Nevertheless, we found that a number of species and groups are in decline, mirroring patterns in other regions of the world. We emphasise that terrestrial arthropods require higher priority within future Arctic monitoring programmes