Understanding urban water performance at the city-region scale using an urban water metabolism evaluation framework.

Water sensitive interventions are being promoted to reduce the adverse impacts of urban development on natural water cycles. However it is currently difficult to know the best strategy for their implementation because current and desired urban water performance is not well quantified. This is particularly at the city-region scale, which is important for strategic urban planning. This work aimed to fill this gap by quantifying the water performance of urban systems within city-regions using 'urban water metabolism' evaluation, to inform decisions about water sensitive interventions. To do this we adapted an existing evaluation framework with new methods. In particular, we used land use data for defining system boundaries, and for estimating natural hydrological flows. The criteria for gauging the water performance were water efficiency (in terms of water extracted externally) and hydrological performance (how much natural hydrological flows have changed relative to a nominated pre-urbanised state). We compared these performance criteria for urban systems within three Australian city-regions (South East Queensland, Melbourne and Perth metropolitan areas), under current conditions, and after implementation of example water sensitive interventions (demand management, rainwater/stormwater harvesting, wastewater recycling and increasing perviousness). The respective water efficiencies were found to be 79, 90 and 133 kL/capita/yr. In relation to hydrological performance, stormwater runoff relative to pre-urbanised flows was of most note, estimated to be 2-, 6- and 3- fold, respectively. The estimated performance benefits from water sensitive interventions suggested different priorities for each region, and that combined implementation of a range of interventions may be necessary to make substantive gains in performance. We concluded that the framework is suited to initial screening of the type and scale of water sensitive interventions needed to achieve desired water performance objectives.

Selection on defensive traits in a sterile caste - caste evolution: a mechanism to overcome life-history trade-offs?

During development and evolution individuals generally face a trade-off between the development of weapons and gonads. In termites, characterized by reproductive division of labor, a caste evolved-the soldiers-which is completely sterile and which might be released from developmental trade-offs between weapons and testes. These soldiers are exclusively dedicated to defense. First, we investigated whether defensive traits are under selection in sterile termite soldiers using allometric analyses. In soldiers of the genus Cryptotermes phragmotic traits such as a sculptured and foreshortened head evolve rapidly but were also lost twice. Second, we compared the scaling relationships of these weapons with those in solitary insects facing a trade-off between weapons and gonads. Defensive traits consistently had lower slopes than nondefensive traits which supports the existence of stabilizing selection on soldier phragmotic traits in order to plug galleries. Moreover, soldier head widths were colony specific and correlated with the minimum gallery diameter of a colony. This can proximately be explained by soldiers developing from different instars. The scaling relationships of these termite soldiers contrast strikingly with those of weapons of solitary insects, which are generally exaggerated (i.e., overscaling) male traits. These differences may provide important insights into trait evolution. Trade-offs constraining the development of individuals may have been uncoupled in termites by evolving different castes, each specialized for one function. When individuals in social insect are "released" from developmental constraints through the evolution of castes, this certainly contributed to the ecological and evolutionary success of social insects.

Cuticular hydrocarbon profiles of dominant versus subordinate male Nauphoeta cinerea cockroaches.

Interactions between male Nauphoeta cinerea cockroaches are characterized by an elaborate ritual that leads to a stable dominant-subordinate hierarchy between two individuals. Chemical signals involving volatile sex pheromones and cuticular hydrocarbons play an important role in establishing and maintaining dominance status. The present study was performed to identify cuticular hydrocarbons in two- and three-times dominant or subordinate individuals obtained by forcing dyadic encounters. Two methods, i.e., solid-phase microextraction (SPME) and organic solvent extraction, were used to isolate cuticular hydrocarbons. A total of 23 peaks of cuticular hydrocarbons were identified. Analysis showed quantitative differences in hydrocarbon profiles of three-times dominant and subordinate individuals according to extraction method and dominance status. Dominant individuals were characterized by higher proportions of the monomethylalkanes 11- and 13-MeC36, 13- and 15-MeC38, and 11-, 13-, and 15-MeC35, while subordinate individuals had higher proportions of the following monomethylalkanes: 7-, 9-. and 11-MeC31, 5-MeC31, 3- and 8-MeC32, and 9-, 10-, 11-, and 12-MeC32. Discussion focuses on the reliability of hydrocarbons as indicators of dominance status and on their correlation with physiological processes.