Geographic body size variation in the periodical cicadas Magicicada: implications for life cycle divergence and local adaptation.

Seven species in three species groups (Decim, Cassini and Decula) of periodical cicadas (Magicicada) occupy a wide latitudinal range in the eastern United States. To clarify how adult body size, a key trait affecting fitness, varies geographically with climate conditions and life cycle, we analysed the relationships of population mean head width to geographic variables (latitude, longitude, altitude), habitat annual mean temperature (AMT), life cycle and species differences. Within species, body size was larger in females than males and decreased with increasing latitude (and decreasing habitat AMT), following the converse Bergmann's rule. For the pair of recently diverged 13- and 17-year species in each group, 13-year cicadas were equal in size or slightly smaller on average than their 17-year counterparts despite their shorter developmental time. This fact suggests that, under the same climatic conditions, 17-year cicadas have lowered growth rates compared to their 13-years counterparts, allowing 13-year cicadas with faster growth rates to achieve body sizes equivalent to those of their 17-year counterparts at the same locations. However, in the Decim group, which includes two 13-year species, the more southerly, anciently diverged 13-year species (Magicicada tredecim) was characterized by a larger body size than the other, more northerly 13- and 17-year species, suggesting that local adaptation in warmer habitats may ultimately lead to evolution of larger body sizes. Our results demonstrate how geographic clines in body size may be maintained in sister species possessing different life cycles.

Infrared thermography and odour composition of the Amorphophallus gigas (Araceae) inflorescence: the cooling effect of the odorous liquid.

During the second blooming of a cultivated Amorphophallus gigas Teijsm and Binnend in the Botanical Gardens of the University of Tokyo, the surface temperature of the inflorescence was measured using an infrared camera. Contrary to studies of other species in the genus Amorphophallus, the surface of the inflorescence showed only very faint thermogenesis and had a lower temperature than that of the background. This cooling effect appeared to be due to a loss of heat through evaporation, which was caused by the secretion of a very large amount of odorous liquid. Chemical analysis revealed that the major components of this liquid were acetic acid, propionic acid, butyric acid and valeric acids. The composition of the odorous liquid was slightly different between the spathe surface and the sterile appendix. The major component(s) of the odorous material from the spathe was butyric acid, and from the sterile appendix was valeric acids. These components would play dual roles of adding the characteristic smell to the inflorescence and cooling the inflorescence.