The University of Minnesota Insect Collection holds a rich collection of bees from Itasca State Park, MN, from 1937 and 1938. This collection formed the historical baseline data for comparison with a new survey conducted from 2011 to 2013, to measure changes in bee species over the last 75 yr. Bees were collected with timed net surveys and trap nests at eight different sites within the park. Megachilidae were the focal family for the current study, due to their importance as commercial pollinators and their unique nesting habits. Species richness and diversity of Megachilidae in the new survey were both significantly lower than that of the historical collection but were not significantly different when species accumulation curves were extrapolated to estimate the true species richness. Eleven species in the historical collection were not rediscovered, while three species not previously collected in Itasca State Park were found in 2011-2013.
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In conclusion, organic additives affect the kinetics of PYP bleach and recovery much more than do inorganic salts. Glycerol and sucrose slow the bleach reaction due to changes in viscosity. This is interpreted in terms of a conformational change of the protein that is induced by light. Aliphatic alcohols and octylglucoside increase the rate constant for bleach and decrease the rate of recovery. We consider this to be due to the exposure of a hydrophobic site on the protein to solvent as a consequence of the phototransformation. The effects of alcohols on the kinetics of the photocycle provide the strongest clue to date on the possible biological function of the yellow protein, which may be to bind to a hydrophobic mem- brane receptor only in the bleached state. This work was supported by grants from the National Institutes of Health (GM21277 to M. A. Cusanovich and DK15057 to G. Tollin) and the National Science Foundation (DMB8718678 to T. E. Meyer).
- long-term change