@article{BreitkopfSchlueterXuetal.2013,
  author    = {Breitkopf, Hendrik and Schl{\"u}ter, P. M. and Xu, S. and Schiestl, Florian P. and Cozzolino, S. and Scopece, G.},
  title     = {Pollinator shifts between Ophrys sphegodes populations: might adaptation to different pollinators drive population divergence?},
  series = {Journal of evolutionary biology},
  volume    = {26},
  journal   = {Journal of evolutionary biology},
  number    = {10},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1010-061X},
  doi       = {10.1111/jeb.12216},
  pages     = {2197 -- 2208},
  year      = {2013},
  abstract  = {Local adaptation to different pollinators is considered one of the possible initial stages of ecological speciation as reproductive isolation is a by-product of the divergence in pollination systems. However, pollinator-mediated divergent selection will not necessarily result in complete reproductive isolation, because incipient speciation is often overcome by gene flow. We investigated the potential of pollinator shift in the sexually deceptive orchids Ophrys sphegodes and Ophrys exaltata and compared the levels of floral isolation vs. genetic distance among populations with contrasting predominant pollinators. We analysed floral hydrocarbons as a proxy for floral divergence between populations. Floral adoption of pollinators and their fidelity was tested using pollinator choice experiments. Interpopulation gene flow and population differentiation levels were estimated using AFLP markers. The Tyrrhenian O.sphegodes population preferentially attracted the pollinator bee Andrena bimaculata, whereas the Adriatic O.sphegodes population exclusively attracted A.nigroaenea. Significant differences in scent component proportions were identified in O.sphegodes populations that attracted different preferred pollinators. High interpopulation gene flow was detected, but populations were genetically structured at species level. The high interpopulation gene flow levels independent of preferred pollinators suggest that local adaptation to different pollinators has not (yet) generated detectable genome-wide separation. Alternatively, despite extensive gene flow, few genes underlying floral isolation remain differentiated as a consequence of divergent selection. Different pollination ecotypes in O.sphegodes might represent a local selective response imposed by temporal variation in a geographical mosaic of pollinators as a consequence of the frequent disturbance regimes typical of Ophrys habitats.},
  language  = {en}
}
@article{JansenCodileanStroevenetal.2014,
  author    = {Jansen, John D. and Codilean, Alexandru T. and Stroeven, A. P. and Fabel, D. and Hattestrand, C. and Kleman, J. and Harbor, J. M. and Heyman, J. and Kubik, P. W. and Xu, S.},
  title     = {Inner gorges cut by subglacial meltwater during Fennoscandian ice sheet decay},
  series = {Nature Communications},
  volume    = {5},
  journal   = {Nature Communications},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/ncomms4815},
  pages     = {7},
  year      = {2014},
  abstract  = {The century-long debate over the origins of inner gorges that were repeatedly covered by Quaternary glaciers hinges upon whether the gorges are fluvial forms eroded by subaerial rivers, or subglacial forms cut beneath ice. Here we apply cosmogenic nuclide exposure dating to seven inner gorges along similar to 500 km of the former Fennoscandian ice sheet margin in combination with a new deglaciation map. We show that the timing of exposure matches the advent of ice-free conditions, strongly suggesting that gorges were cut by channelized subglacial meltwater while simultaneously being shielded from cosmic rays by overlying ice. Given the exceptional hydraulic efficiency required for meltwater channels to erode bedrock and evacuate debris, we deduce that inner gorges are the product of ice sheets undergoing intense surface melting. The lack of postglacial river erosion in our seven gorges implicates subglacial meltwater as a key driver of valley deepening on the Baltic Shield over multiple glacial cycles.},
  language  = {en}
}
@article{LopezBarqueroXuDesiatietal.2017,
  author    = {Lopez-Barquero, Vanessa and Xu, S. and Desiati, Paolo and Lazarian, Alex and Pogorelov, Nikolai V. and Yan, Huirong},
  title     = {TeV Cosmic-Ray Anisotropy from the Magnetic Field at the Heliospheric Boundary},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {842},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0004-637X},
  doi       = {10.3847/1538-4357/aa74d1},
  pages     = {14},
  year      = {2017},
  language  = {en}
}