Floral resource pulse decreases bumble bee foraging trip duration in central Wisconsin agroecosystem

1. Resource pulses, narrow periods of high resource availability, can elicit strong behavioural responses across diverse taxa. Mass‐flowering agricultural crops are an example of a resource pulse that insect pollinators exploit. However, the underlying mechanism behind changes in pollinator behaviour associated with mass‐flowering crops is still relatively unexplored. 2. The present study quantified the behavioural response of bumble bees, an important wild pollinator, to commercial cranberry bloom, an important mass‐flowering crop in Wisconsin, U.S.A. Over a 2‐year period, foraging trip duration was measured using radio frequency identification at 14 farms situated across landscape contexts, ranging from high to low natural area (woodland amount). Using transect surveys, floral resource abundance at a landscape scale was estimated. 3. It was found that bumble bees were highly sensitive to temporal changes in landscape‐level resource abundance associated with the onset of cranberry bloom, during which they decreased foraging trip duration by 22% and increased the number of foraging trips during bloom by 24% on average relative to the period before and after bloom. This phenomenon was consistent across colonies, individual bees, and landscape contexts, despite a higher abundance of flowers in low woodland landscapes. Bumble bee colonies growing in low‐ and high‐woodland landscapes exhibited a similar performance. 4. As mass‐flowering crops are probably a factor influencing bumble bee foraging behaviour in agricultural regions, investigations should continue into how variable resource landscapes, particularly those offering resource pulses, affect wild pollinators and the pollination services they provide.     

Genomics detects population structure within and between ocean basins in a circumpolar seabird: The white‐chinned petrel

The Southern Ocean represents a continuous stretch of circumpolar marine habitat, but the potential physical and ecological drivers of evolutionary genetic differentiation across this vast ecosystem remain unclear. We tested for genetic structure across the full circumpolar range of the white‐chinned petrel (Procellaria aequinoctialis) to unravel the potential drivers of population differentiation and test alternative population differentiation hypotheses. Following range‐wide comprehensive sampling, we applied genomic (genotyping‐by‐sequencing or GBS; 60,709 loci) and standard mitochondrial‐marker approaches (cytochrome b and first domain of control region) to quantify genetic diversity within and among island populations, test for isolation by distance, and quantify the number of genetic clusters using neutral and outlier (non‐neutral) loci. Our results supported the multi‐region hypothesis, with a range of analyses showing clear three‐region genetic population structure, split by ocean basin, within two evolutionary units. The most significant differentiation between these regions confirmed previous work distinguishing New Zealand and nominate subspecies. Although there was little evidence of structure within the island groups of the Indian or Atlantic oceans, a small set of highly‐discriminatory outlier loci could assign petrels to ocean basin and potentially to island group, though the latter needs further verification. Genomic data hold the key to revealing substantial regional genetic structure within wide‐ranging circumpolar species previously assumed to be panmictic.     

Studies on the enzymatic reduction of N-Boc-4S-amino-3-oxo-5-phenylpentanoic acid methylester.

The enzymatic reduction of N-Boc-4S-amino-3-oxo-5-phenylpentanoic acid methylester, the key intermediate in the stereoselective synthesis of a statinanalogue, was studied with Hansenula anomala and Hansenula silvicola. Using whole cells of H. anomala gives complete conversion and a diastereomeric excess of 88% of the desired 3S, 4S statinanalogue. The strain contains two NADPH-dependent oxidoreductases, that can be separated by ion exchange chromatography or gelfiltration, yielding the 3S, 4S or 3R, 4S stereoisomers, respectively, with > 99% diastereomeric excess (DE). In the crude extract the 3S, 4S oxidoreductase is very unstable and could be purified with < 1% yield only. In contrast, H. silvicola, which gave poor conversions using whole cells, exhibited about 80-fold higher specific activity in the crude extract than H. anomala. The NADPH-dependent oxidoreductase was purified 317-fold in 12% yield. A single enzyme of 54 kDa reduces the substrate with 97.4% DE. Besides the statinanalogue a wide range of other compounds could be reduced, most notably diones and chinones such as isatin or campherchinone. It was demonstrated that the enzymes often discussed for the reduction of beta-ketoesters with yeast e.g. L-3-hydroxyacyl CoA dehydrogenase (EC 1.1.1.35), the beta-ketoreductase of the fatty acid synthase complex and also the 3-hydroxy-3-methyl glutaryl-CoA dehydrogenase (EC 1.1.1.34) are separated during the purification steps from the oxidoreductase acting on N-Boc-4S-amino-3-oxo-5-phenylpentanoic acid methylester. The physiological role of the new enzyme is still unknown.