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In many Drosophila species the male courtship song is an essential part of a successful courtship, playing a role in species-recognition and/or in sexual selection exercised by the females on conspecific males. In Drosophila montana, specific traits of the courtship song (the length and the carrier frequency of sound pulses) have earlier been shown to play an important role in intraspecific mate choice. Here we show that the male song (especially the interpulse interval) also plays a role in species-recognition, maintaining sexual isolation between sympatric species. We succeeded in breaking down sexual isolation between D. montana females and D. lummei males by playing the females simulated courtship song with a species-specific interpulse interval while they were courted by a mute (wingless) male. Involvement of different song traits in intra- and interspecific mate choice suggests that the song may be affected by both directional and stabilizing selection.

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A method has been developed for the characterization of biologically active silver birch (Betula pendula) inner bark phenolics based on high-performance liquid chromatography/diode array detector (HPLC-DAD)/electrospray ionization-mass spectrometry (ESI-MS). It was demonstrated that the inner bark contains high amounts of flavonoids, arylbutanoids, diarylheptanoids, simple phenolic compounds, phenolic acids, lignans, and procyanidins. Altogether, 30 individual compounds were characterized based on their ultraviolet (UV) and MS data. Structures of 22 compounds were confirmed by nuclear magnetic resonance (NMR) spectroscopy. In addition to previously reported phenolic compounds, 12 compounds were identified in silver birch inner bark for the first time; two of them are novel compounds: 3-β-glucopyranosyloxy-2-hydroxy-1-(4-hydroxy-3-methoxy-phenyl)-propan-1-one and 1,7-bis-(4-hydroxyphenyl)-3-heptanol 3-O-β-ap-iofuranosyl-(1→2)-β-glucopyranoside.

Barking up the right tree: The spirodienone sesquineolignan pinobatol (1), a long‐time speculated monomeric unit of lignin, was isolated from the 70 % aqueous acetone extract of pine (Pinus sylvestris L.) bark. Its structure was determined by high‐resolution electron ionization mass spectrometry and a variety of NMR spectroscopic techniques.

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