Control of environamental variables in a field study using a chronobiological protocol

RESUMO

Field work in chronobiology usually is based on observations which differ from those in laboratory studies which are experimental. Non-invasive protocols are recommended in the field in order not to introduce additional variables. We propose an alternative strategy here. The effect of environmental cycles on biological rhythms can be estimated when the observations are made in more than one area. The areas under study must have at least one characteristic in common which is a guarantee that the limits of oscillation of an environmental cycle will be similar. This proposal has been tested using the biological system consisting of an Onagraccae plant, Ludwigia elegans, and its bee visitors, which is found in two localities at the same latitude, but at different altitudes. Under the same photoperiod, but with the mean temperature ranging within known limits, it was possible to determine temporal characteristics of the system in the field by examining the effects of the light/dark and temperature daily cycles.